In this article, Board member of the SP Foundation in the USA, HSPer and medical doctor, Malin Dollinger, discusses assessment and testing for a baclofen pump.
Have you considered getting tested for the effectiveness of a baclofen pump or are curious about what is involved?
The correct procedure for a test injection is to insert a small catheter, using a local anesthetic, into the subarachnoid space (where the permanent catheter will go, if you decide to do this). This is inserted into the skin of the lower back, much the same place as a spinal anesthetic is placed.
Then the first test dose of Baclofen e.g. 50micrograms, is given through the catheter. It may produce the desired effect, reducing spasticity and improving walking, or may have an excess effect, rendering you temporarily paralyzed (for an hour or two, till it wears off). If that happens, the correct procedure is to repeat the test using a 25microgram dose. This is again through the catheter, already correctly placed. If paralysis occurred with the 50microgram dose, the 25microgram may produce the desired reduction in spasticity, to allow walking.
What happened to me, previously, is that they did not insert a catheter, but simply a needle, then injected the “test dose” of 50micrograms, which rendered me paralyzed. They said “I failed the test” and I never got the pump. Likely had they repeated the test using a half-dose of Baclofen, it might have produced exactly the desired effect.
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Oral vs pump Baclofen
Same drug, same effect, but the oral dose is much much greater in order for a tiny part of that oral dose to get into the spinal cord/brain and produce the anti-spasticity effect. Problem is often that the large oral dose produces sleepiness, confusion, tiredness, etc, which may not be tolerable, even if the walking/spasticity is better. The advantage of the tiny pump dose is that it goes directly where it needs to work, and doesn’t produce the “whole body” side effects sometimes found with the oral medication.
UK HSPer, Adam Lawrence, who is well known to the Australian HSP community through his annual surveys on issues related to living with HSP, shares his experience of being tested for urine retention/bladder emptying and talks about a way to manage that where it is a significant problem, intermittent self-catheterisation.
Thursday, 26 January 2017 Intermittent Self-Catheterisation
Last week a nurse from the local incontinence came to visit, following a referral from my GP as a result of their letter from the HSP clinic in London. The main purpose of the visit was to measure my PVR (post void residual urine volume), but also for me to find out more about Intermittent Self-Catheterisation, or ISC for short.
It seems that ISC is a solution that some people go for with their bladder issues, and that has been a comment made in a few survey responses. I wanted to find out about this so that when it comes to making that decision myself I’ve got some knowledge.
The bladder collects waste from the kidneys. The kidneys produce this continuously, and it is collected in the bladder so you can pass it when you need to. Messages are sent from the bladder to the brain to indicate that bladder needs to be emptied, and then messages are sent back down to both contract the bladder muscle and relax the sphincter muscle, which starts off the flow through your urethra. The process should continue until the bladder is completely empty.
A few basics are described – normally the bladder should not contain more than 350-400ml. Normally we urinate about 4 to 6 times a day and occasionally at night.
The ISC is a tube which is inserted along the urethra and into the bladder, which then allows your urine to drain. It indicates that it may take a long time for the bladder to drain. Advice is given if you find it difficult to insert the catheter (cough or try to pass urine), how to stop dips/drops (put your finger over the end of the catheter).
Advantages to ISC are given:
protects kidneys
reduces risks of unrinary tract infections (UTIs)
improve quality of life
improve comfort
reduce risk of complications and disease
improve continence
reduce residual urine
increase autonomy
not interfere with your sex life.
It seems that there are a number of different products, and it is important to select the right option, length and diameter. The LoFric catheters have a hydrophilic coating which creates a very wet and slippery surface when activated by water, which minimises friction. Other catheters use a gel instead.
It is recommended that catheterising is done in clean and suitable facilities, but notes that such conditions are not always available, and some catheters include integrated sterile water and handling aids – useful if you’re not able to wash your hands before starting.
Measuring PVR (post void residual urine volume)
Back to the nurse visit. She came armed with an ultrasound scanner. As might be expected I was unable to pass urine whilst she was here. She measured the amount of liquid in my bladder to be around 250ml, a couple of hours after using the toilet. I went to the toilet about half an hour after she left and measured my urine volume – about 250ml. My conclusion is that I don’t have a high PVR, and therefore at a low risk of infection, so no need to alter what I’m doing at the moment.
A particular type of SPG11 HSP known to respond to the drug levodopa, has been successfully treated in a young woman in the US using deep brain electrical stimulation.
Deep-brain stimulation (DBS) of the globus pallidus interna (GPi) significantly improved symptoms in a patient with refractory parkinsonism and a specific genetic mutation.
Researchers believe this is the first case of juvenile-onset levodopa-responsive parkinsonism secondary to a mutation in the spatacsin gene (SPG11) treated with GPi DBS.
They also collected what they think are the first electrophysiologic basal ganglia data in this condition.
“The importance of this report is to alert physicians that if they have a patient with symptoms that resemble Parkinson’s disease in early adulthood, with stiffness in the legs, they should consider this mutation,” author Adolfo Ramirez-Zamora, MD, Department of Neurology, Albany Medical Center, New York, told Medscape Medical News. “Although rare, it is something that actually responds to DBS.” Read more…
SOURCE: JAMA Neurol. Published online November 7, 2016. Letter, Viewpoint
Cognitive functions, including social cognition should be systematically assessed in HSPers to improve clinical management.
“Brain fog” is how one HSPer describes his mental state as he can no longer concentrate as well as he used to, or for as long.
The nine SPAST (SPG4) HSPers in this French study averaged 52 years old and had HSP symptoms for an average of 16 years. The study found:
no intellectual disability or dementia
all have mild cognitive impairment including attention deficit
90% have executive function disorders, affecting goal formation, planning, goal-directed action, changing goals, switching focus, self-monitoring and attention or focus, amongst others
80% have impaired social cognition, which can be thought of as the brain’s capability applied to social situations, including expressing emotions and noticing the emotions of others, as well as the ability to understand the potential mental states and intentions of others
one HSPer, who shows no physical symptoms but carries a known SPAST mutation, shows mild cognitive impairment just like the others
no correlation was found between mental and physical impairment, age of onset of HSP, or disease duration
cognitive disorders might sometimes occur before motor disorders.
Objectives
To describe cognitive assessment including social cognition in SPG4 patients.
Methods
We reported a series of nine patients with SPG4 mutation with an extensive neuropsychological examination including social cognition assessment.
Results
None of our patients presented with intellectual disability or dementia. All presented with mild cognitive impairment with a high frequency of attention deficit (100%), executive disorders (89%), and social cognition impairment (78%). An asymptomatic patient for motor skills presented with the same cognitive profile. No correlation was found in this small sample between cognitive impairment and motor impairment, age at disease onset, or disease duration.
Conclusions
SPG4 phenotypes share some cognitive features of frontotemporal lobar degeneration and amyotrophic lateral sclerosis. Cognitive disorders including executive disorders and social cognition impairment are frequent in SPG4 patients and might sometimes occur before motor disorders. Therefore, cognitive functions including social cognition should be systematically assessed in order to improve the clinical management of this population.
Significant improvements were found in spasticity, walking ability and hand dexterity, with no adverse side effects reported.
Building on the results of an earlier study http://www.hspersunite.org.au/dalfampridine-fampyra-may-improve-mobility-in-hsp/, this second study into the use of dalfampridine (Fampyra in Australia) to improve spasticity in HSP produced similar findings. Extended-release dalfampridine improves the walking speed and muscle strength of lower extremities; the slow-release formulation minimizes toxicity and thus increases the utility of the drug in patients with multiple sclerosis (MS) [1].
The clinical pattern of hereditary spastic paraparesis (HSP) is similar to the spastic gait evident in some patients with MS [2]. The clinical and pathological similarities between HSP and some forms of MS encouraged us to ask whether dalfampridine might aid in the treatment of patients with HSP.
Patients
Five consecutive patients with possible HSP were included. Genetic tests confirmed diagnoses of HSP in 4 patients.
Methods
Dalfampridine-SR (10mg) was administered twice daily. Data were recorded using the criteria of the Modified Ashworth Scale (MAS), 9-hole peg test (NHPT). The 10 and 20m walk tests were videotaped. All assessments were performed just before dalfampridine administration (baseline) and 15 days later (end-of-study).
Results
All patients were females, with a mean age of 35.2 ± 10.8 years (range 22-49 years). Muscle strength did not change between assessments. The baseline mean MAS score was 2.0 ± 0.7, and the end-of-study score was 1.0 ± 0.0 (95% CI 0.122-1.878, p = 0.034).
The time taken to walk 10m decreased significantly (18.3 ± 5.8 vs. 14.6 ± 6.5 s; 95% CI 1.4-5.9, p = 0.014). The mean percentage improvement was 27.8 ± 9.1%. The time taken to walk 20m also tended to decrease, but the difference was not significant (35.8 ± 11.6 vs. 30.5 ± 13.3 s, p = 0.150). The time required to complete the NHPT was reduced from baseline; the difference was significant for the left hand (20.5 ± 2.2 vs. 18.5 ± 2.5 s, p = 0.025) but not for the right (19.4 ± 3.3 vs. 18.2 ± 2.9 s, p = 0.539).
Discussion
The aim of the HSP treatment is to ameliorate symptoms and to improve strength and balance via physical therapy and rehabilitation. We prescribed 10mg dalfampridine for some patients with HSP.
Patients with HSP, who were administered dalfampridine, exhibited significant improvements in walking ability, spasticity, and hand dexterity, as measured (respectively) by the Timed-25-Foot Walk Test, MAS, and NHPT instruments. This is the second study to explore the efficacy of dalfampridine to treat HSP. Béreau et al. [3] showed that dalfampridine was effective in 6 of 12 patients.
A principal difference between our study and that of Béreau et al. [3] is that we compared hand dexterity before and after treatment, and found that the drug significantly improved such dexterity.
The adverse effects of dalfampridine include seizures, dizziness, nausea, and balance disorders [4]. No patient reported any adverse effect of treatment.
In conclusion, dalfampridine may be a safe alternative treatment for patients with HSP who complain of walking impairments; the drug reduced spasticity and improved hand dexterity.
Disclosure Statement
The authors have declared no conflict of interest regarding this article. The author(s) received no specific funding for this work.
I am pleased to announce the launch of the 2016 on-line survey for people with HSP. The main focus for this survey is understanding fatigue, which many with HSP experience. 3 different short-form fatigue questionnaires are offered, and I will be interested to see which people prefer. There are questions on bladder and bowel issues. Bladder issues are well known, but whilst bowel issues are reported less frequently there still seem to be many who have them. Finally, there are questions about how people find out information about HSP.
As with previous years, results will be collected until early 2017, then analysing these in time to publish the results on my blog on Rare Disease day, 28th Feb 2017. This year, I am also collecting e-mail addresses to build up a list of people interested in taking part in these surveys in future years.
International Meeting on Spastic Paraparesis and Ataxias
Here is a summary of the International Meeting on Spastic Paraparesis and Ataxias organised by the Spatax network and the Ataxia Study Group. The meeting was held over 3 days in Paris in June 2016. I have gone into more detail on my blog than I have in this column, so readers are welcome to go and see more there: http://hspjourney.blogspot.co.uk/2016/06/international-meeting-on-spastic.html
The meeting was really friendly, and I felt quite at home there. The network of researchers feels really close knit, and I was pleased to see and hear about people chatting with each other and sharing their knowledge and findings. In many respect the coffee breaks, lunches and evening social events are just as important as the presentations as they allow people to go and share ideas.
I spent some time talking with the people from Euro HSP who are keen for the UK group to join. This is quite the opposite to the EU referendum held in the UK on the first day of the meeting (and reported in the second day) which resulted in the beginning of the UK’s EU exit. I also think that the various patient groups need to work together, and not just the HSP groups, but those groups for people with similar conditions – Ataxia, CMT, ALS and others.
International HSP Meeting – key thoughts:
Anyone can read further details on who said what on my blog.
The knowledge of HSP increases. The day-to-day variation in symptoms for an individual can be significantly greater than the year-to-year progression of HSP. One group identified potential biomarkers for HSP, which correlate well with disease severity, and another group report the progression of changes in gait with progression of HSP. There were several papers looking at how the different types of HSP have different ages of onset, different levels of severity and different symptoms. The genetic mutations for HSP can vary in size, and potentially affect more than one gene, with potentially more than one consequence.
Several researchers talked about genetic testing, with some noting that test results can be ambiguous. Whilst the number of genetic tests for HSP grows they still only cover about 20% of cases, leaving some 80% without a clear diagnosis. Another issue is that such a test can show “incidental” findings – i.e. a gene is matched which was not part of the original search remit – consent is needed from the patient to find and report these findings.
Researchers are looking for bigger/better patient registries. There are genetic and clinical overlaps between Ataxia, HSP and ALS, as well as other conditions, with symptoms and the way they feature being common between conditions. Working together and sharing data helps. Some are calling for the usual ‘pure’/’complex’ classification of HSP to be revised. Overall, some 5-10% of rare disease patients have two different conditions. Changes in health can be indicators of underlying problems, for example a chronic cough.
In terms of new treatments, one study reported the use of Simvastin for one patient with SPG5A. This reduced a specific type of cholesterol encoded by the affected gene.
Treatments are more effective the earlier they are given. Various drugs and therapies were mentioned, but the overall message was that if these are given after the symptoms are severe there is less chance of recovery, particularly if the nerve cells have died. Some researchers are looking at repurposing existing drugs for HSP.
Several groups reported balance training, gait training and the use of wearable “stabilisers” for patients with Ataxia. I don’t know if such approaches would also work for HSP. It’s an avenue for someone to research. It was said that the gait training was found by the participants to be difficult to do, but showed good results. This ties in with the “use it or lose it” slogan.
Several researchers use and talked about animal models of HSP. Whist I accept that this could be considered controversial; these models do greatly help the understanding of diseases.
Here are two new videos on exercise and stretching from the SP Foundation in the USA that are good, simple and easy to follow and use.
These exercises can be done at home without any special equipment. The people doing the exercises and stretching in the videos are HSPers – and that’s a plus!
Around 75% of older HSPers experience lower urinary tract symptoms such as urgency, hesitancy and incontinence, with some developing complications that include infections, stones, swelling of the kidneys due to urine buildup, and kidney failure.
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HSPers with urinary issues should seek specialist assessment to improve management and avoid or diminish complications, resulting in better quality of life.
OBJECTIVE:
Hereditary spastic paraplegia (HSP) represents a clinically and genetically heterogeneous group of neurodegenerative diseases, with a worldwide estimated prevalence of 1.3/100,000 [1]. The “pure” form of HSP is characterized by a progressive spastic paraplegia, often associated with lower urinary tract symptoms (LUTS) (72.4% to 77.6%) [2,3]. However, urologic complications are rarely reported. The aim of this study was to characterize clinical and urodynamic aspects of LUTS following HSP, and to describe treatment and urological complications of LUTS in a large series of HSP patients.
MATERIALS/PATIENTS AND METHODS:
We performed a monocentric retrospective evaluation based on review of medical records of HSP patients admitted in the department of PRM from 1999 to 2016. Inclusion criteria were patients>18years. Presenting HSP. Clinical, urodynamic and radiologic data were recorded. Statistical analysis was performed using Microsoft Excel software.
RESULTS:
Thirty-three HSP patients were included. Mean age was 62±14 years with 70% of men. The mean follow-up was 8.10±5 years. Patients presented LUTS: urgency (85%), hesitancy (85%), nocturia (56%) and urinary incontinence (54%). The post-void residual volume (PVR) was over 100mL in 70%. NDO was diagnosed according to urodynamic testing in 83% of patients, associated in 76% of them with a detrusor-sphinctger-dyssinergia (DSD). HSP patients were exposed to urologic-nephrologic complications: febrile urinary tract infections (25%), urolithiasis (21%), hydronephrosis (8%) and renal failure (17%). HSP patients have been mainly treated with anticholinergics (69%) and 10% were switched to intradetrusor botulinum toxin. Clean intermittent catheterization was performed by 30% of patients. Three patients underwent a non-continent surgical urinary diversion.
DISCUSSION/CONCLUSION:
A significant percentage of HSP patients presenting with LUTS mainly resulting of the association of PVR, DO and DSD. However, for the first time, uro-nephrologic complications following LUTS related to HSP are underlined. Thus, HSP patients should be assessed, such as SCI patients, in order to improve management and HSP patients’ quality of life with a decrease of uro-nephrologic complications.
Neurogenic detrusor overactivity in patients with hereditary spastic paraplegias.
Joussain C1, Levy J2, Charlanes A3, Even A3, Falcou L3, Chartier-Kastler E4, Denys P3.
1 Versailles Saint-Quentin University, Versailles, France, Medical School Paris Île-de-France Ouest, Inserm U1179, Montigny-le-Bretonneux, France. Electronic address: charles.jsn@free.fr.
2 Versailles Saint-Quentin University, Versailles, France, Medical School Paris Île-de-France Ouest, Inserm U1179, Montigny-le-Bretonneux, France.
3 Hôpital Raymond-Poincaré AP-HP, Department of Physical Medicine and Rehabilitation, Garches, France.
4 Pitié-Salpêtrière Academic Hospital, Assistance Publique-hôpitaux de Paris, Pierre and Marie Curie Medical School, Paris 6 University, Department of Urology, Paris, France.
There have been very few studies of HSP gait, but two significant studies, one in Italy and one in France, have just been published. The Italian study of 50 HSPers identified three distinctive gait patterns that matched closely with the level of mobility impairment. The critical factor is the range of motion at the hip, knee and ankle joints. The most restricted range of motion matched with highest spasticity and slowest walking speed.
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In the French study, 12 HSPers undertook two walking tests. Spasticity and weakness were found to be greatest in the outside part of the calf muscle (gastrocnemius lateralis), with simultaneous contractions of this muscle and the shin muscle (tibialis anterior) on the front of the lower leg found to be significantly increased compared with non-HSP gait.
Italian HSP gait study
BACKGROUND:
Spastic gait is a key feature in patients with hereditary spastic paraparesis, but the gait characterization and the relationship between the gait impairment and clinical characteristics have not been investigated.
OBJECTIVES:
To describe the gait patterns in hereditary spastic paraparesis and to identify subgroups of patients according to specific kinematic features of walking.
METHODS:
We evaluated fifty patients by computerized gait analysis and compared them to healthy participants. We computed time-distance parameters of walking and the range of angular motion at hip, knee, and ankle joints, and at the trunk and pelvis. Lower limb joint moments and muscle co-activation values were also evaluated.
3 HSP gait patterns identified
RESULTS:
We identified three distinct subgroups of patients based on the range of motion values. Subgroup one was characterized by reduced hip, knee, and ankle joint range of motion. These patients were the most severely affected from a clinical standpoint, had the highest spasticity, and walked at the slowest speed. Subgroup three was characterized by an increased hip joint range of motion, but knee and ankle joint range of motion values close to control values. These patients were the most mildly affected and had the highest walking speed. Finally, subgroup two showed reduced knee and ankle joint range of motion, and hip range of motion values close to control values. Disease severity and gait speed in subgroup two were between those of subgroups one and three.
CONCLUSIONS:
We identified three distinctive gait patterns in patients with hereditary spastic paraparesis that correlated robustly with clinical data. Distinguishing specific features in the gait patterns of these patients may help tailor pharmacological and rehabilitative treatments and may help evaluate therapeutic effects over time.
1 Department of Medico-Surgical Sciences and Biotechnologies, University of Rome Sapienza, Latina, Italy.
2 Rehabilitation Centre, Policlinico Italia, Rome, Italy.
3 Department of Engineering, Roma TRE University, Rome, Italy.
4 Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, INAIL, Monte Porzio Catone, Rome, Italy.
5 Centre of Space Bio-Medicine, University of Rome Tor Vergata, Rome, Italy.
6 Laboratory of Neuromotor Physiology, Istituto Di Ricovero e Cura a Carattere Scientifico Santa Lucia Foundation, Rome, Italy.
7 Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy.
8 Fondazione Don Gnocchi, Milan, Italy.
9 G.B. Bietti Foundation-IRCCS, Department of Neurophysiology of Vision and Neurophthalmology, Rome, Italy.
10 IRCCS, Neuromed, Pozzilli, Isernia, Italy.
French HSP gait study
OBJECTIVE:
Hereditary spastic paraplegia (HSP) designates a rare genetic disorder characterized by the existence of a pyramidal syndrome and/or paresis of the lower limbs, resulting in locomotor disorders. The objective of this study was to investigate the HSP patients walking characteristics during a comfortable walking speed, to determinate the most deleterious impairments and their evolutivity during a prolonged standardized walk. A second goal was to study the co-contraction of targeted muscles during these two walking conditions.
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MATERIAL/PATIENTS AND METHODS:
In this prospective study, the spatio-temporal parameters (GAITRITE® electronic walkway) and electromyographics (surface EMG) of twelve HSP patients were compared with those of nine matched subjects, for the walking conditions: « comfortable walk », « Six Minutes Walking Test » (SMWT). The perceived exertion was assessed by the Borg scale. HSP patients received a standardized interrogatory and neuro-orthopedic examination measuring angles, joint values, spasticity (Tardieu scale) and muscle strength (MRC scale). For every subject, muscle activations and co-contractions indices were analyzed for several muscles: semi-tendinosus (ST), rectus femoris (RF), gastrocnemius lateralis (GL) and tibialis anterior (TA) for all walking conditions.
RESULTS:
Median gait speed (0.85m/s) and cadence (91steps/min) were significantly lower in the HSP group compared with unaffected subjects. Walking speed was constant over the SMWT for a high level of exertion. Spasticity and weakness were greatest for the GL muscle that had a prolonged activation during the swing phase. Co-contraction indices in the GL/TA couple were significantly increased for the non-dominant lower-limb during swing phase. No significant differences were found for the RF/ST couple. The motor deficit was the only significant parameter found to correlate with walking speed.
DISCUSSION-CONCLUSION:
HSP patients are characterized by a slow walk explained mainly by a motor deficit. Surface EMG seems to be an interesting tool in the therapeutic reflection to investigate walking disorders in HSP disease.
by Adrienne Sexton, Genetic Counsellor, & A/Prof. Michael Fahey, Neurogeneticist (Neurogenetics clinic, Royal Melbourne Hospital)
Dr. Adrienne Sexton Ph.D. Genetic Counsellor
Assoc. Prof. Michael Fahey, Neurologist/Geneticist
What are the chances of finding a gene change (DNA mutation) for HSP?
If no genetic testing has occurred previously for that person or family, the chance of finding a genetic cause seems to be about 50% (Lynch et al. 2016; Kara et al. 2016; Kumar et al. 2013). But if common genes like SPAST or SPG11 are excluded, the chance of finding a genetic cause for HSP in a family with no previous testing drops to around 25-30% (Kumar et al. 2013; Lynch et al. 2016; Kara et al. 2016). Chances of finding a genetic cause may be lower in populations where less is known about which HSP genes are the most common.
Why are different percentages reported in different studies?
Most of the studies so far have not had large numbers of participants, and have used multi-gene panels or exome sequencing. Some of the reasons that different research articles quote different DNA mutation detection rates for HSP are due to differences in:
which individuals with HSP were included (their symptoms, age that symptoms began, population/ethnicity they are from)
whether people had already been screened for the most common gene or genes, eg. the SPAST gene
whether people had a family history of HSP, making it more likely that a dominant genetic cause will be found
whether the researchers are including DNA variants that might be a cause of HSP as well as those DNA mutations that are already proven to cause HSP, and
how many HSP genes were analysed.
What is Next Generation Sequencing (NGS)?
For many years, testing of the more common HSP genes (spastin, REEP1 and atlastin) one gene at a time was available, and the test would look through the thousands of letters of DNA code in one of those genes, to identify a change. This same principle of looking through the letters of the DNA code can now be applied to many genes at once. This is a leap forward in genetic testing technology and is called Next Generation Sequencing (other names are panel testing, whole exome sequencing, and Massively Parallel Sequencing).
Some types of gene changes go undetected
Some types of gene changes still will not be detected by this form of testing, and it is very likely there are undiscovered genes for HSP that may be able to be tested for eventually.
The types of gene changes causing HSP that will currently be missed are:
when part or all of the gene is missing (deletions)
when part or all of the gene is duplicated
when there are repeated letters of the DNA many times over (eg. CAGCAGCAGCAGCAG)
when the gene change affects the regulation of the gene, rather than the parts that code for the gene product (protein).
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What are the different tests using next-generation sequencing?
Next-generation sequencing can be used in a number of different ways:
multi-gene panels, where some or all of the currently known HSP genes are tested. Many panels have included 15, 20, 30 genes – more than 40 genes are currently known, and more than 70 genetic types of HSP, although not all the genes for these have been found.
whole exome sequencing, where all known genes are sequenced, but due to the huge volume of DNA data, only genes for HSP and related conditions would be analysed. To keep this in perspective, we each have more than twenty thousand genes, so it is currently not feasible for the lab scientists to analyse each and every letter of the DNA code for each person’s test. Sometimes a condition is caused by a change to a single letter of the DNA code, which is like looking for a needle in a haystack.
whole genome sequencing, where all known genes are sequenced plus all the “junk DNA” (98% of our genome) which is still largely unknown. See A Guide to Your Genome . Usually only genes linked with HSP and neuromuscular conditions would be analysed (due to the time and complexity of the analysis process) but this can check some of the regulatory regions of genes as well as the parts coding for the gene product (protein).
This website gives some more info about how genetic testing is used, depending on your own situation:
Lynch, David S.; Koutsis, Georgios; Tucci, Arianna; et al. (2016) Hereditary spastic paraplegia in Greece: characterisation of a previously unexplored population using next-generation sequencing . EUROPEAN JOURNAL OF HUMAN GENETICS Volume: 24 Issue:6 Pages: 857-863
