HNPP · Physical Health

The difference between HNPP, CMT and CIDP

cell

One of the first responses that seems to appear on search engines about Hereditary Neuropathy with Liability to Pressure Palsies is its relation to the inherited condition Charcot Marie-tooth syndrome (group of disorders). While CMT1A – a subtype of the CMT – is thought to be the most common inherited neuropathic condition, little research is still available to its ‘sister’ condition HNPP. So how do the conditions diverge and converge?

The irony of the conditions being similar in nature, is the fact HNPP is the genetic opposite of CMT1A. HNPP is associated with a deletion on the same chromosomal site where CMT1A (the most common type of CMT) has been found to have a duplication, and it contains an important myelin gene, peripheral myelin protein-22 gene (PMP22).

The chromosome in question is chromosome 17, where CMT1A has an extra copy of PMP22, and HNPP results from the loss of a copy of PMP22. The PMP22 gene encodes for peripheral myelin protein, and disruption of this gene leads to a dysfunctional myelin sheath on nerves.

dna

What is a chromosome?

Going back a step and remembering the old science lessons from school, a cell’s nucleus contains chromosomes – rod shaped bodies found in the nucleus of cells that contain genetic information in the form of DNA.

DNA (deoxyribose nucleic acid) is made up of short sections of genes – inherited from parents, and makes up DNA which controls part of a cell’s chemistry, particularly protein production. Each gene codes for a specific protein by specifying the order in which amino acids must be joined together.

CMT

In total, humans normally have 46 chromosomes in each cell, divided into 23 pairs. Two copies of chromosome 17, one copy inherited from each parent, form one of the pairs. In one of the arms of the chromosome 17 (if you think about it as an ‘X’ type shape), specifically the ‘P-arm’ lies the gene PMP22 labelled as 17p11.2, which is the area where it resides. The genetic defect in most HNPP patients is a 1.5 Mb deletion (used to describe the length of a DNA/RNA molecule) on this chromosome containing the PMP22 gene.

HNPP is usually caused by an autosomal dominant gene, which means one parent must be affected. While there should be two copies of the PMP22 gene, there usually is only one or some form of mutation, unlike with CMT1A which tends to be a duplication of the gene. As a result, HNPP and CMT tend to be lumped together under one category and while there may be an overlap, there are other forms of CMT and HNPP that do not follow this rule.

The result of this is that the symptoms of each condition resemble one another because they both end up becoming a form of demyelinating neuropathy.

Rare forms of HNPP

Point mutations in the PMP22 gene are a rare cause of HNPP. In one case, a novel PMP22 splice site mutation – a genetic mutation that inserts, deletes or changes a number of nucleotides in the specific site – was reported in an HNPP family. Nucleotides are organic molecules that form DNA and RNA (ribonucleic acid, which is an important molecule with long chains of nucleotides).

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According to a 2006 study, a mutation at nucleotide c.179+1 was found in the PMP22 gene. This mutation causes the synthesis of an abnormal mRNA. Messenger RNA (mRNA), are molecules in cells that carries codes from the DNA in the nucleus to the sites of protein synthesis in the cytoplasm (the ribosomes).

Point mutations of PMP22 gene cause a wide variety of demyelinating neuropathies including HNPP, Charcot‐Marie‐Tooth disease type 1A (CMT1A), Dejerine‐Sottas syndrome (DSS), and congenital hypomyelination (CH). Authors of the 2006 study say: “To date, 11 mutations have been reported in HNPP patients and all of them are likely to cause a loss of function of the protein.” An earlier 2003 report suggested there were “fewer than 10 point mutations of the PMP22 gene” associated with HNPP.

Rare forms of CMT

CMT1B

CMT1B is the second most common subtype of CMT1. CMT1B is caused by a defect within the MPZ gene, which lies on chromosome 1. The MPZ gene produces myelin protein zero, and disruption of this gene also causes deficits within the myelin sheath. CMT1B patients have onset and symptoms similar to those of CMT1A patients, although there is a wide range of variability within CMT1B. As discussed in the article When HNPP ‘Causes Breathing Problems’, the MPZ gene is known to be associated with respiratory issues which is less common with HNPP.

CMT1E

Similar to point mutations in HNPP, instead of having a duplication of the normal PMP22 gene, CMT1E patients harbour different genetic abnormalities in the PMP22 gene.

CMTX

CMTX is caused by mutations in the gene for connexin 32, which normally codes for a protein located in myelin, the insulating sheath that surrounds nerve fibres. It has many of the same symptoms of CMT1 and CMT2, including muscle weakness and atrophy, and changes in sensation, mostly in the feet, lower legs, hands and forearms. However, because of its linkage to the X chromosome, CMTX often affects males more severely than females.

CMT2

CMT Type 2 (CMT2) is a subtype of CMT that is similar to CMT1 but is less common. It is typically autosomal dominant, but in some cases can be recessive. CMT2 is caused by direct damage to the nerve axon itself in comparison to CMT1 which results from damage to the myelin sheath insulating the axon. CMT2 is commonly referred to as “axonal” CMT.

CMT2A is the most common subtype of CMT2 and is caused by defects in the MFN2 gene. The MFN2 gene encodes for Mitofusin 2, which is a protein involved in the fusion of cellular mitochondria. Other more rare forms of CMT2 and their gene defects include:

  • CMT2B is caused by defects in the RAB7 gene.
  • CMT2C is caused by defects in the TRPV4 gene.
  • CMT2D is caused by defects in the GARS gene.
  • CMT2E is caused by defects in the NEFL gene.

CMT4

CMT4 is a rare subtype of CMT that is inherited in an autosomal recessive pattern. Generally, cases of CMT4 present with more severe symptoms compared to CMT1 or CMT2. In general, CMT4 is caused by defects in the myelin sheath which insulates the axon. However, other variations include:

  • CMT4A is caused by defects in the GDAP1 gene.
  • CMT4B is caused by defects in the genes MTMR2 (CMT4B1), or MTMR13 (CMT4B2).
  • CMT4C is caused by defects in the SH3TC2 gene.
  • CMT4D is caused by defects in the NDRG1 gene.
  • CMT4E is caused by defects in the EGR2 gene.
  • CMT4F is caused by defects in the PRX gene.
  • CMT4H is caused by defects in the FDG4 gene.
  • CMT4J is caused by defects in the FIG4 gene.

Source: CMT USA

Chronic Inflammatory Demyelinating Polyneuropathy

Asked about the similarities of Chronic inflammatory demyelinating polyneuropathy with HNPP and CMT, the symptoms that manifest seem to overlap with HNPP and CMT. However, the major difference is the fact that it is not an inherited condition, but a neurological disorder that causes progressive weakness and impaired sensory function in the legs and arms. No clear genetic predisposition or other predisposing factors for CIDP have been identified.

CIDP is thought to be caused by the immune system mistakenly attacking and damaging the myelin sheath of the peripheral nerves hence the symptoms may appear to be similar to HNPP and CMT. It is said that many people with CMT are initially diagnosed with CIDP due to these symptoms.

After that short science lesson, it’s clear to see how easily one condition can be mistakenly diagnosed for another. The symptoms tend to overlap with one another because the end result can include damage to the myelin sheath and neuropathic tendencies. As a result, it requires careful analysis by health professionals, and the necessity that all essential medical tests are undertaken to get the correct answers.

Read: Why do some HNPP results appear negative?

Read: HNPP, belief and the impact of misdiagnosis

 

HNPP · Physical Health

When HNPP ’causes breathing problems’

Lungs

If you didn’t think it was possible, but some individuals with HNPP claim they suffer from breathing problems due to anomalies with certain nerves. Breathing problems associated with hereditary neuropathy are often ignored because most doctors don’t know they can be part of the disorder.

While hyperventilation is less common, weakness of the thoracic diaphragm, which enables people to breathe, and the nerve linked to it is suggested to cause problems with breathing.

Disclaimer: Please ask your medical practitioner or doctor for more information. This article is based on various research, journals and testimonies.

Why does it happen?

HNPP makes the nerves very susceptible to trauma, which plays a pivotal role when it comes to the act of inhaling and exhaling. There are several major issues that create specific problems:

Hypoglossal Nerve

The hypoglossal nerve is the twelfth paired nerve in the brain. Its name is derived from ancient Greek, ‘hypo‘ meaning under, and ‘glossal’ meaning tongue. The nerve has a purely somatic motor function, innervating the majority of the muscles of the tongue.

According to the 2015 study Disorders of the Lower Cranial Nerves by authors Josef Finsterer and Wolfgang Grisold, the nerve directs not only voluntary activities of the tongue, but also involuntary functions, such as clearing the mouth of saliva by swallowing. They report that some people with HNPP have been reported to have issues with this specific nerve. The authors state: “Another [lower cranial nerve] involved in HNPP is the hypoglossal nerve. The affection of the hypoglossal nerve has been also reported in other types of hereditary neuropathy.”

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Researchers at the Department of Neurobiology, Tokyo Metropolitan Institute for Neuroscience, say that there is a distinct link between swallowing and breathing. Using six rats, they report: “The XII nerve activity preceding that of the phrenic nerve (pre-I XII nerve activity) was markedly exaggerated during periods when this relation was disrupted”.

The phrenic nerve plays an important role in breathing because the nerve originates in the neck passes down between the lung and heart to reach the diaphragm. It is responsible for controlling the contractions of the diaphragm, which allows the lungs to take in and release air and make us breathe properly. During the above experiment with the rats, the authors say that “nerve activity was also shown to couple with swallowing in the same manner as ‘real’ inspiratory activity.”

You may experience this when your breath arrests for a moment while attempting to swallow, which brings me neatly on to the significance of the phrenic nerve.

Phrenic Nerve

Nerve fibres of the phrenic nerve, spinal nerves, and laryngeus recurrens nerve project to the diaphragm, abdominal, intercostal, and laryngeal muscles. While it is considered “exceptional”, some HNPP sufferers do face these symptoms.

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In the 2016 report Laryngeal and Phrenic Nerve Involvement in a Patient with Hereditary Neuropathy with Liability to Pressure Palsies, the participant is said to have had vocal cord paralysis as well as “latency of the right phrenic nerve” and reduced right hemi-diaphragm – the muscle that separates the chest cavity from the abdomen and that serves as the main muscle of respiration.

The study suggests that a person with comorbidity, or someone who suffers from several separate illnesses which in this case was chronic obstructive pulmonary disease (COPD), can consequently end up with breathing issues. They also say that this was rectified through COPD treatment. Potential weight loss from HNPP could be a triggering factor.

This video by Professor Mary Reilly from the National Hospital for Neurology in London, UK, explains breathing issues for those suffering from the inherited condition Charcot Marie-Tooth syndrome:

Brachial plexopathy can be an issue withh HNPP sufferers. It is a form of peripheral neuropathy which occurs when there is damage to the brachial plexus, an area on each side of the neck where nerve roots from the spinal cord split into each arm’s nerves. Nerves outside the brachial plexus, extends from the spinal cord, through the cervicoaxillary canal in the neck, over the first rib, and into the armpit.

The phrenic nerve receives stimuli from parts of both the cervical plexus and the brachial plexus of nerves. As Satish Khadilkar and Snehaldatta Khade state in the Official Journal of Indian Academy of Neurology: “Hereditary neuropathy with pressure palsies can present phenotypically like acute brachial plexopathy. But, unlike the classical phenotype, recurrence is unusual.”

Hence damage to this area could potentially weaken signals and cause breathing difficulties.

How likely is it occur?

However, it’s important to note that respiratory issues are more common with the inherited condition Charcot Marie-Tooth syndrome. In a 2016 study including 49 patients with genetically confirmed CMT or HNPP, those with a duplication of the PMP22 gene as well as those with a mutation of the MPZ gene were more likely to face issues with breathing. The HNPP participants were recorded not to have faced respiratory problems.

The authors of Underestimated Associated Features in CMT Neuropathies say that those with the CMT2-I/J (Charcot Marie-Tooth syndrome Type 2) condition had certain mutations in the MPZ gene causing “respiratory insufficiency”, which obviously reiterates the rarity of this occurring when a person suffers from HNPP.

This video, made by CMTA, explains what’s going on in more detail:

The organisation CMT UK has recommended the following, which may be applicable to those with HNPP if you feel that you are suffering from breathing issues.

What to do if you think you’re having breathing difficulties

  • Have your doctor send you to a cardio-pulmonary specialist for a sleep study.
  • Suggest that your maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP) be tested both sitting and lying down.
  • If you are having bad morning headaches you could be retaining CO2. The above tests will show that.
  • You can elevate the head (from the waist) of your bed two or three inches by putting bricks under the legs or a suitcase under the mattress.
  • You can keep your weight down.
  • Make sure you have had a pneumonia and flu vaccinations (ask your GP) and treat respiratory infections aggressively.

As mentioned, breathing problems is rather a rare symptom to be associated with HNPP. That being said, there is still a lot of research to be undertaken to establish other symptoms associated with the condition. The main thing is not to hold back and visit your medical practitioner if you feel there may be a problem.

Read: Can HNPP lead to bone-related issues?

HNPP · Medication · Physical Health

What to avoid with HNPP

Taxol
Rotation of the model of the Paclitaxel molecule – Andrew Ryzhkov

An interesting discussion emerged on one of the HNPP groups about how certain products can actually have a reverse effect on the nerves. While there are hundreds of results when it comes to what to eat or how to help neuropathic symptoms, it’s rather a different situation when you attempt to search foods, supplements or drugs to be cautious about. So what should we keep an eye on?

Disclaimer: Please ask your medical practitioner or occupational therapist for more information. This article is based on various research, journals and testimonies.

Vitamin C

This a hot topic of debate with some saying that high doses of vitamin C can actually reduce the amount of PMP22 produced, while others saying they have seen some benefits through increased energy. So what’s the deal?

While there is little research to show the effects of vitamin C on HNPP specifically, there has been studies revealing how it affects the inherited condition Charcot Marie-tooth syndrome.

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In the 2004 study Ascorbic Acid Treatment Corrects the Phenotype of a Mouse Model of Charcot-Marie-Tooth Disease, the authors claimed to see an improvement from ascorbic acid (vitamin C). They say: “Ascorbic acid treatment resulted in substantial amelioration of the CMT-1A phenotype, and reduced the expression of PMP22 to a level below what is necessary to induce the disease phenotype.

“As ascorbic acid has already been approved by the FDA [Federal Drug Administration] for other clinical indications, it offers an immediate therapeutic possibility for patients with the disease.”

While the authors saw benefits by reducing the expression of PMP22, it may be difficult to say whether this will have a reverse effect for those with HNPP, which consists of already having a deletion or defection of one of two of these genes.

On the other hand, a study of 277 persons with CMT1A found no significant effect of a daily 1.5-g dose of ascorbic acid after two years. The researchers of the 2011 study Ascorbic Acid in Charcot–Marie–Tooth disease type 1A states: “With respect to the size of the effect of ascorbic acid, if the effect is so small that only a biomarker can detect it, it would be unlikely to be clinically significant in a short-term study but might be important in the long term.

“Findings of this study suggest that ascorbic acid is not efficacious in adults with CMT1A.”

As with any supplements, it’s important not to take an excessive amount. As Thomas Bird, MD, writing for GeneReviews, a genetic resource page for clinicians, states: “No specific treatment for the underlying genetic or biochemical defect exists and no special diet or vitamin regimen is known to alter the natural course of HNPP.”

Always check with your medical practitioner about possible effects and let them know about your condition.

Vincristine 

Vincristine is a known chemotherapy drug used to treat several types of cancer including acute leukaemia, malignant lymphomas and carcinomas. If you’re suffering from multiple illnesses, this is where it gets complicated.

Vincristine_3D
Vincristine 3D structure

The medication is said to be potentially “toxic” to those with peripheral neuropathy due to its side effects that resemble the same symptoms. These can include numbness, pin prick or a tingling sensation to full-blown motor difficulties and neuritic pain.

In one study, 61 per cent of the 23 patients treated for lymphoma developed neuropathy, while only 14 per cent of the 37 patients with other malignant diseases developed these symptoms.

There has also been a case report of a patient with a familial variant of Charcot-Marie-Tooth syndrome. After receiving two 2mg dosages, his weakness secondary to peripheral neuropathy rapidly progressed to complete paraplegia. Acute acoustic nerve palsy has also been reported.

Hence letting your medical team know about the condition that you have and how you are affected can help avert a crisis such as this.

Taxol

Paclitaxel, sold under the brand name Taxol among others, is a chemotherapy medication used to treat a number of types of cancer. This includes ovarian cancer, breast cancer, lung cancer, Kaposi sarcoma, cervical cancer, and pancreatic cancer.

toxic
“Toxic Neuropathies” – Kelley’s Essentials of Internal Medicine, H. David Humes, 2001

Drugs and medications such as taxol that are known to cause nerve damage should be avoided, says Vinay Chaudry, MD, in a 2003 study Toxic Neuropathy in Patients With Pre-Existing Neuropathy. Chaudry says that six patients with pre-existing neuropathy, who received “non-toxic” dosages of known neurotoxic agents including taxol, had significantly worsened. He concludes: “functionally disabling toxic neuropathy can occur in patients with pre-existing neuropathy at standard doses.”

The Charcot-Marie-Tooth Association has maintained a “Medical Alert” list of potentially neurotoxic medications. They define taxol as a “definite high risk” to those with the condition even if the individual may not present any symptoms.

Fluoroquinolones

The fluoroquinolones are a family of broad spectrum, systemic antibacterial agents that have been used widely as therapy of respiratory and urinary tract infections. It is an antibiotic used to treat some infectious or even common diseases.

However, in 2016, the U.S. Food and Drug Administration advised that the serious side effects associated with fluoroquinolone antibacterial drugs generally outweigh the benefits for patients with neuropathic issues.

“The peripheral neuropathy reported with fluoroquinolone administration can be severe, debilitating, and permanent.”

A Case Report on a Rare but Serious Debilitating Side-Effect of Fluoroquinolone Administration – Jacquelyn K. Francis and Elizabeth Higgins, MD, 2014.

In a statement, the FDA said: “An FDA safety review has shown that fluoroquinolones when used systemically (i.e. tablets, capsules, and injectable) are associated with disabling and potentially permanent serious side effects that can occur together. These side effects can involve the tendons, muscles, joints, nerves, and central nervous system.”

In one 2014 case report for the Journal of Investigative Medicine, a 57-year-old woman was treated for a urinary tract infection with a ciprofloxacin, an antibiotic under the fluoroquinolones umbrella. She had already been in remission for 12 years after suffering from trigeminal neuralgia. Two years after the initial onset of symptoms, she continued to suffer from polyneuropathies chronologically related to ciprofloxacin use.

As the report concludes: “the peripheral neuropathy reported with fluoroquinolone administration can be severe, debilitating, and permanent. It is for this reason that physicians need to practice due diligence when prescribing not only antibiotics, but any drug.”

While it’s important to understand how the wrong drugs can interact with hereditary neuropathy, it’s even more essential to talk about it with the right people. Letting health professionals know about your current situation will allow them to prescribe the right medication. As one HNPP’er says because there’s an assumption that something is safe, doesn’t mean it’s safe for us.

HNPP · Physical Health

Why do some HNPP results appear negative?

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Genetic testing for HNPP can be daunting, mostly because it can be a confirmation of all your worst fears. At the same time, it can come as a relief for many, as it marks the start of an official journey. But what happens when your results turn up negative?

As the NHS website explains, we need two peripheral myelin protein-22 (PMP22) genes, one from each parent, for the normal development of the peripheral nerves. These genes provide instructions for the creation of PMP22 protein, which makes up the protective outer layer of each nerve. This outer layer, which is a bit like the plastic coating that insulates a wire, is called myelin.

“It would have been nice to feel the immediate gratification of a positive HNPP test result. It would have answered nearly every question I had about what was happening to my body.”

From the Girl With A Purple Cane blog

In HNPP, one copy of the PMP22 gene is lost (deleted) so that people have only one copy of this gene. A person with HNPP will have inherited a faulty copy of the PMP22 gene from one of their parents.

With only one normal PMP22 gene, their myelin is fragile and more susceptible to injury. Just the slightest pressure, stretch or repetitive movement on the nerve causes sections of the myelin to be lost. Signals cannot be relayed to and from the muscles properly.

A genetic test usually confirms whether one of the copies is deleted. Around 80 per cent  of cases of HNPP is down to deletions of this particular gene. However, in some cases even with a genetic test, it can come back negative.

According to DNA diagnostic experts GeneDx, genetic diagnosis is identified in approximately 50-70 per cent of individuals with the hereditary neuropathic condition Charcot-Marie-Tooth disease, which shows that even if the symptoms present themselves, they may not be explicitly diagnosed for all.

This was seen in a 2006 study where a 32-year-old woman diagnosed with CMT, where the PMP22 genes are duplicated, came back with a false negative even though she had two different types of gene mutations.

gene testing HNPP hereditary neuropathy
Algorithm for Peripheral Neuropathy testing – GeneDx

What happens if the results are positive?

A positive result indicates that a disease-causing mutation was identified in the individual who was tested. In this case, you can get predictive genetic testing in terms of planning ahead as well as testing for your family. They can then go ahead for further evaluation. There can be variability in symptoms, age of onset, and disease severity even among members of the same family who have the same genetic mutation.

What if the results are negative?

Even with a negative test result, it does not rule out that a person with neuropathy does not have a genetic condition. As the diagnostic company suggests possible reasons for a negative result could be:

  • The patient has a mutation in a gene not included in the testing panel
  • The patient may have a mutation in a part of a neuropathy gene that was not covered by the test
  • The patient does not have hereditary type of neuropathy

As Sharon Plon, Medical Geneticist and Director of MD-PhD program at Baylor College of Medicine, says:

Unknown results

In some cases, results may not conclusive either way. These results are referred to as variant of unknown clinical significance (VUS). This indicates that the role of the genetic change in causing neuropathies has not clearly been established. In some cases, testing of other family members may help clarify the clinical significance of a VUS.  The greater the number of affected family members who carry the VUS, the greater the likelihood that the identified variant is hereditary.

In other instances, if the person is the only one identified with a single mutation, they may be a heterozygous carrier i.e. they inherit a pair of genes where one is dominant and one is recessive.

Advantages of getting a panel test if negative

  • Higher diagnostic rate
    • all ‘common’ genes in one test
    • the rare genes included/ genes that no diagnostic service is available
    • more patients and families to get a genetic diagnosis
  • Faster turn around time
    • all genes in one test, not sequential testing
  • Familial cases can avoid further clinical investigations
  • Enhance our knowledge and understanding for IPN genes (Enrich for fragments of interest)
    • routine testing of rare genes
    • interaction between genes/ modifying mutations
  • Cost savings
    • directly: panel testing is cost effective
    • indirectly: faster result / high diagnostic rate can lead to reduced
    • appointments and other investigations for patient and family

However, the cost of a genetic test depends on the complexity of the test and can range from under £100 to £1000s, for example a basic chromosome test (karyotype) would cost about £150 and screening a panel of 108 genes associated with congenital cateracts costs £1100. The cost increases if more than one test is necessary or if multiple family members need to be tested. So it can be a hefty investment depending on where you’re getting it done.

The problems with certain gene tests

Either way, as some research states, the CMT1A duplication was identified more frequently than the HNPP deletion, suggesting some types of gene variants are more difficult to detect to than others such as those for HNPP.

The study, Charcot-Marie-Tooth Disease And Related Hereditary Polyneuropathies featured in the Genetics in Medicine journal, says: “HNPP can mimic multifocal neuropathy, a frequently inflammatory disorder that requires immunosuppressant therapy.

“Molecular testing occasionally identifies new sequence variations of unknown pathogenic significance. In these cases further studies (segregation analysis, functional assay) are required to establish pathogenicity, which are performed in research laboratories.”

Hence there is still quite a lot of testing to be done to perfect the current sequencing method. So hopefully it won’t come as a shock if your results turn out to be negative, but be prepared for that eventuality.

HNPP · Mental Health · Physical Health

Dealing with genetic testing with HNPP

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Getting genetically tested can be traumatic depending on the outcome, but for many it is a necessity. The uncertainty of not knowing for either yourself or your family can be a harrowing experience, but what comes next may appear to be more difficult. However, a diagnosis for HNPP can help explain how conditions are inherited, in order to help draw up medical management plans and discuss further family planning options.

“There are no right answers, there are simply decisions.”

Asked on the Inspire Forum for Inherited Neuropathy

The psychological effect of a genetic disorder can vary by the nature of the condition and the relationship of a person to the affected individual. Every family is different and it is difficult to predict how people will react to a genetic diagnosis. It’s helpful to think in advance about some of the possible reactions, though, so you can react quickly and minimise distress.

Disclaimer: Please ask your medical practitioner or doctor for more information. This article is based on various research, journals and testimonies.

The following information has been taken from Understanding Genetics: A New England Guide for Patients and Health Professionals:

Patients

A genetic diagnosis can be a great relief to the person suffering from the condition.  It helps HNPP sufferers understand their disorder, especially when the condition is rare and the patient has struggled to find a diagnosis. Patients often spend years living with a condition without knowing its name or cause. Diagnoses usually lead to improved treatment options and access to support services. They can also help other family members make decisions about their own lives.

However, a genetic diagnosis may lead to negative reactions, too. The science of genetics can be confusing, and sufferers are often frustrated until they understand the nature of their condition. Anyone identified with a mutation may consider themselves at fault or interpret their diagnoses as leading to something they cannot fight. A genetic diagnosis can lead to fears about insurance and employment discrimination.

The reaction to a diagnosis varies from individual to individual.

Parents

Understandably, the diagnosis of a genetic condition may put stress on a relationship. Couples with an affected child often face difficult family planning decisions because future children may be at higher risk. Depending on the condition, parents may also be faced with hard choices regarding prenatal testing. It can also put a strain on relationships some times causing a communication breakdown. The magnitude of these decisions and their outcomes has an impact on the individuals involved and on their relationship.

Family 

Unaffected family members should not be forgotten in the case of a genetic disorder. When one family member is diagnosed with a mutation, family members who do not have the mutation often feel guilt that loved ones are affected when they are not.

“When my daughter was in junior high, she told me that if it’s hereditary, it was my responsibility to figure it out. I’ve had various inconclusive genetic tests but am hopeful this next one will pinpoint it. The info won’t affect me in any way, but maybe generations from now, it could be life-changing.”

Asked on the Inspire Forum for Inherited Neuropathy

Siblings of children with special needs sometimes feel neglected because parents need to focus more time and effort on their siblings. Including unaffected family members in the planning of care for individuals with genetic conditions can help them come to grips with their own emotional issues.

Adults who are diagnosed with a genetic condition and are considering having a child will need to consider the risk of having an affected child as well as their ability to care for the child.

Myelinated_neuron

Genetic test results are often complex and may be difficult for patients and their families to understand. In some cases, a genetic test may reveal the risk status of other family members who may not wish to know this information, potentially encroaching upon their autonomy or privacy.

In general, support or advocacy groups and community resources can provide ongoing support to patients and their families with genetic conditions. Support groups provide a forum for sharing experiences about caring for a family member affected with a genetic condition, coping with a new diagnosis, obtaining healthcare or other services, and healing. Members of support groups know first-hand what it means to be faced with a diagnosis and to need accurate, up-to-date information. Staying connected with their community helps individuals fight the feelings of isolation that often surround families living with a genetic condition.

That being said, knowing what to expect during the testing process can help to prepare for what’s to come.

How to prepare for a genetic appointment

There are several things it is helpful to consider and find out before your genetic appointment, these include:

  • Take questions with you – Thinking through your concerns and queries in advance and writing them down to take with you
  • Check where the appointment will be – Genetic centres can be based in clinics across different hospitals so double-check with your hospital
  • Give details of other family member’s genetic diagnosis – If another member of your family has previously been seen in the genetic clinic, please let the clinic know their name and date of birth before your appointment. This will help them link the family information and will save time at your appointment.
  • Gather as much information about your family history – You are likely to be asked for this in your appointment. Clinics usually only ask about your family history as far back as grandparents.
  • If you want someone else tested who isn’t present – If your concern is about a genetic diagnosis affecting another member of the family, the clinic will need to get confirmation of the diagnosis. You may be asked to pass a consent form to your relative before your appointment.
  • Ask for help if you need additional assistance – It is very helpful to let the clinic know in advance.

What does an appointment involve and what happens after?

  • You will be seen by a clinical geneticist or a genetic counsellor, or both, depending on the reason you have been referred.
  •  Your medical and family history will be taken.
  • If needed, you/your child will be examined by the doctor.
  • Where a diagnosis is known, you will be provided with information about the condition including an explanation of how it is inherited and what this may mean for you and other members of your family.
  • Options around genetic testing and family planning will be discussed if appropriate.
  • Support will be offered around decisions that need to be made
  • If genetic testing is available and you wish to go ahead with this, then you may have a blood sample taken.
  • Following your appointment it is likely you will be sent a letter summarising the information discussed.
  • You may only need to attend the clinic once or several appointments may be needed. You will be told at your appointment whether you need to be seen again.
  • If you had a blood sample taken for genetic testing, you should be told when to expect the results and agree a plan for how you will receive these.
  • Some types of results are always given in person in the clinic or by letter.

What next?

  • Genetic counselling – this involves a healthcare professional talking to you about a genetic condition or possible genetic condition affecting you, your child or another member of your family. Another important aspect of genetic counselling is that it provides support with the emotional and family implications of a genetic disorder.
  • Be wary of information you find on the internet – The internet is a powerful tool for diagnosis and support but there is a lot of misinformation out there and some of the things you read might be frightening. Remember, genetic conditions can manifest themselves differently in different people – every one of us is unique.
  • Connect with other people – This is a great way to share advice and support one another.
  • Know your rights – Apart from coping with the emotional and medical issues related to a positive genetic test result, patients are often faced with life-changing decisions, especially when it comes to family planning and thinking about genetic testing for your children. But it’s also important to check where your genetic information is going and how it is being used so ask about it during your appointment.

To find out more information about genetic testing and counselling, here are some organisations that deal with this specifically: