** Update: summary of my depression posts here: http://hspjourney.blogspot.co.uk/2017/10/summary-of-depression-posts.html ***
In my recent browsing around the internet I was quite interested to find this paper: http://cre.sagepub.com/content/23/9/857 Basically it says (from the abstract only) that many people with HSP have mild depression, and that the depression is correlated with mobility. I'm not sure why I haven't picked up on this aspect so far?
In my understanding of whats (potentially) coming up for me, and in reading of various pages by others with the condition I am not surprised. Once you realise whats coming, you know your life is going to be different and that your mobility is going to be reduced. Because the condition is gradual this gives plenty of time for thinking about what might happen and how things might be different and there don't seem to be too many "at leasts.....".
All this thinking can lead to a more bleak outlook on the future, which I take to be another way of expressing depression. I can see that this may be much stronger for those who place a high value on activities which are mobile (sports, outdoor life, pets, children etc.) than for those who place a high value on potentially less mobile activities (art/literature, computing, films/TV, communicating etc.).
Wearing my fact finding hat I'm interested to find out about the Beck Depression Inventory (which is used in the study) and am interested to learn more details than wikipedia has to offer. http://en.wikipedia.org/wiki/Beck_Depression_Inventory. My geek hat suggests that the level of depression would be correlated with the inverse of mobility - i.e. less mobile=more depressed, but I don't know how they were measuring mobility. Interested to see a copy of the full paper.
This blog records my journey to Hereditary Spastic Paraplegia (HSP, also known as Familial Spastic Paraparesis or FSP). I was diagnosed with SPG4 in 2009 when my wife became pregnant with our first child. I currently wear insoles, do daily stretches and weekly Pilates. I take medication for my bladder. I tweet about HSP, RareDisease and other things @munkee74.
Thursday, 22 September 2011
Monday, 12 September 2011
Symptoms Update (Riding my bike)
OK, so another brief post in the never ending list of things which may or may not be relevant.
I cycle to work. Its 6-7miles each way (10-11km), and I can do this in about half an hour. In the last few weeks I've been noticing that my feet gradually move forwards on my pedals as I continue my journey. I wonder if my quads are getting more tight, preventing my knee from flexing quite as far on its way back.
I cant work out if getting some SPDs would be worth a try, or if thats going to turn out to be more trouble than its worth.
I cycle to work. Its 6-7miles each way (10-11km), and I can do this in about half an hour. In the last few weeks I've been noticing that my feet gradually move forwards on my pedals as I continue my journey. I wonder if my quads are getting more tight, preventing my knee from flexing quite as far on its way back.
I cant work out if getting some SPDs would be worth a try, or if thats going to turn out to be more trouble than its worth.
Tuesday, 23 August 2011
Community Pages
I was browsing facebook the other day, and found a couple of HSP community pages, and this led me on to have a bit of a trawl around to find out if were are any other pages around. This gives another set of links like the support groups, but perhaps a bit more up-to-date and personal? I would welcome any links to other community pages.
Facebook:
http://www.facebook.com/pages/Hereditary-Spastic-Paraplegia-HSP/121279057942990
http://www.facebook.com/pages/HSP-Australia/199236076788479
http://www.facebook.com/pages/HSP-Research-Foundation/137857172915152
http://www.facebook.com/pages/Familial-spastic-paraparesis-FSP/210236818990197
http://www.facebook.com/pages/Hereditary-spastic-paraplegia/132525713451982
Medical/patient community pages:
http://www.rarediseasecommunities.org/en/community/hereditary-spastic-paraplegia/article/hsp-article
http://freyerse.org/
http://www.wemove.org/forum/ubbthreads.php/forums/8/1/Hereditary_Spastic_Paraplegia
http://www.patientslikeme.com/conditions/493-hereditary-spastic-paraplegia
Facebook:
http://www.facebook.com/pages/Hereditary-Spastic-Paraplegia-HSP/121279057942990
http://www.facebook.com/pages/HSP-Australia/199236076788479
http://www.facebook.com/pages/HSP-Research-Foundation/137857172915152
http://www.facebook.com/pages/Familial-spastic-paraparesis-FSP/210236818990197
http://www.facebook.com/pages/Hereditary-spastic-paraplegia/132525713451982
Medical/patient community pages:
http://www.rarediseasecommunities.org/en/community/hereditary-spastic-paraplegia/article/hsp-article
http://freyerse.org/
http://www.wemove.org/forum/ubbthreads.php/forums/8/1/Hereditary_Spastic_Paraplegia
http://www.patientslikeme.com/conditions/493-hereditary-spastic-paraplegia
Tuesday, 16 August 2011
HSP Prevalence
OK, so, in my internet trawl so far I have found several references to the prevalence of HSP in the general population. Some of these prevalence's have been referenced to studies and papers which provide further details. I've managed to find downloads for four different papers which give prevalence for HSP, and these papers all contain summaries to previous prevalence papers. This post combines all these papers together and tries to estimate the prevalence of HSP. I have found some further papers which have not been referenced in any of these four studies, but I'm going to leave those for inclusion in a further post.
So, the four papers I found in full are:
Erichsen et al, Norway, 2009: http://brain.oxfordjournals.org/content/132/6/1577.full.pdf
Monagle et al, Ireland, 2002: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1737699/pdf/v072p00043.pdf
Coutinho et al, Portugal, 1999: http://archneur.ama-assn.org/cgi/content/full/56/8/943
Polp et al, Spain 1991: http://brain.oxfordjournals.org/content/114/2/855.abstract?ijkey=c0472af598cf8de455d3b4f7839277c2f74d87be&keytype2=tf_ipsecsha (this sometimes asked for payment, but other times didn't)
From this, I get an overall list of the following studies into the prevalence of HSP:
This shows some interesting things to me. Generally these studies all relate to separate geographic areas, apart from there being two Norway and two Portugal, so, I will exclude the earlier and smaller studies from each of these countries to avoid double counting.
The main outliers in the data sets are the studies from Japan and Guam, with the Japan study having by far the largest overall population. On the whole the other studies give broadly the same results, and (apart from Libya) relate to European populations. This gives opportunities for combining data sets:
Some while ago I read Guns Germs and Steel (http://www.amazon.co.uk/Guns-Germs-Steel-history-everybody/dp/0099302780 - a very interesting read) and this leads me to think that conditions would have different prevalence's in different parts of the world. So, I'll concentrate my analysis on the area where the main proportion of studies have been done - Europe. I would suggest that the overall prevalence of HSP in the European population is about 3 per 100,000 population, but noting that several of the papers indicated they thought their studies presented an underestimate.
Perhaps with further analysis I'll be able to draw out some further thoughts...
I was able to find an abstract for all of the papers listed except the Lucci paper of 1982, which appears to be strangely elusive. I would welcome contact from anyone who has a full copy of these papers (or links to other locations) to add to my collection! For completeness, links to abstracts for the other papers follow:
Guam, Chen, 1968: http://archneur.ama-assn.org/cgi/content/summary/19/6/573
Denmark, Werderlin, 1975: http://onlinelibrary.wiley.com/doi/10.1111/ane.1986.73.issue-S106/issuetoc
Norway, Skre, 1980: http://onlinelibrary.wiley.com/doi/10.1111/j.1399-0004.1974.tb00647.x/abstract
Libya, Sridharen, 1985: http://brain.oxfordjournals.org/content/108/4/831.abstract
Italy, Brignolio, 1986: http://www.springerlink.com/content/39x4u4351261153v/
Japan, Hirayama, 1989: http://www.ncbi.nlm.nih.gov/pubmed/8059595
Italy, Filla, 1992: http://www.ncbi.nlm.nih.gov/pubmed/1512613
Italy, Leone, 1995: http://www.ncbi.nlm.nih.gov/pubmed/7793232
Portugal, Silva, 1997: http://www.jclinepi.com/article/S0895-4356(97)00202-3/abstract
The missing reference:
Italy, Lucci, 1982: Lucci B, Motti L, Guidetti D, Zucco R. Indagine epidemiologica descritiva delle eredoatassie nella provincia di Reggio-Emilia. In: Atti del III Convegno Nazionale di Neuroepidemiologia. 1982;p. 169–174
So, the four papers I found in full are:
Erichsen et al, Norway, 2009: http://brain.oxfordjournals.org/content/132/6/1577.full.pdf
Monagle et al, Ireland, 2002: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1737699/pdf/v072p00043.pdf
Coutinho et al, Portugal, 1999: http://archneur.ama-assn.org/cgi/content/full/56/8/943
Polp et al, Spain 1991: http://brain.oxfordjournals.org/content/114/2/855.abstract?ijkey=c0472af598cf8de455d3b4f7839277c2f74d87be&keytype2=tf_ipsecsha (this sometimes asked for payment, but other times didn't)
From this, I get an overall list of the following studies into the prevalence of HSP:
| Location | 1st Author | Year | Cases | Population | Prevalence per 100,000 |
| Guam | Chen | 1968 | 7 | 37975 | 18.4 |
| Denmark (Zealand) | Werderlin | 1975 | 23 | 1179000 | 2 |
| W. Norway | Skre | 1980 | 31 | 725000 | 12.1 |
| Italy (Reggio Emilia) | Lucci | 1982 | 4 | 412324 | 1 |
| Libya | Sridharan | 1985 | 11 | 519000 | 2.1 |
| Italy (Torino) | Brignolio | 1986 | 31 | 2327996 | 1.3 |
| Japan | Hirayama | 1989 | 109 | 123000000 | 0.17 |
| Spain (Cantabria) | Polo | 1991 | 49 | 510000 | 9.6 |
| Italy (Molise) | Filla | 1992 | 9 | 335211 | 2.7 |
| Italy (Valle d'Aosta) | Leone | 1995 | 5 | 115270 | 4.3 |
| Portugal | Silva | 1997 | 5 | 250061 | 2 |
| Portugal | Coutinho | 1999 | 106 | 3786000 | 2.8 |
| Ireland | Monagle | 2002 | 69 | 5436000 | 1.27 |
| Norway | Erichsen | 2009 | 194 | 2633893 | 7.4 |
This shows some interesting things to me. Generally these studies all relate to separate geographic areas, apart from there being two Norway and two Portugal, so, I will exclude the earlier and smaller studies from each of these countries to avoid double counting.
The main outliers in the data sets are the studies from Japan and Guam, with the Japan study having by far the largest overall population. On the whole the other studies give broadly the same results, and (apart from Libya) relate to European populations. This gives opportunities for combining data sets:
| Analysis | Cases | Population | Prevalence |
| All studies excluding Skre 1980 and Silva 1997 | 617 | 140292669 | 0.44 |
| All studies excluding Skre 1980 and Silva 1997 and Japan | 508 | 17292669 | 2.94 |
| All European studies excluding Skre 1980 and Silva 1997 | 495 | 16985755 | 2.91 |
Some while ago I read Guns Germs and Steel (http://www.amazon.co.uk/Guns-Germs-Steel-history-everybody/dp/0099302780 - a very interesting read) and this leads me to think that conditions would have different prevalence's in different parts of the world. So, I'll concentrate my analysis on the area where the main proportion of studies have been done - Europe. I would suggest that the overall prevalence of HSP in the European population is about 3 per 100,000 population, but noting that several of the papers indicated they thought their studies presented an underestimate.
Perhaps with further analysis I'll be able to draw out some further thoughts...
I was able to find an abstract for all of the papers listed except the Lucci paper of 1982, which appears to be strangely elusive. I would welcome contact from anyone who has a full copy of these papers (or links to other locations) to add to my collection! For completeness, links to abstracts for the other papers follow:
Guam, Chen, 1968: http://archneur.ama-assn.org/cgi/content/summary/19/6/573
Denmark, Werderlin, 1975: http://onlinelibrary.wiley.com/doi/10.1111/ane.1986.73.issue-S106/issuetoc
Norway, Skre, 1980: http://onlinelibrary.wiley.com/doi/10.1111/j.1399-0004.1974.tb00647.x/abstract
Libya, Sridharen, 1985: http://brain.oxfordjournals.org/content/108/4/831.abstract
Italy, Brignolio, 1986: http://www.springerlink.com/content/39x4u4351261153v/
Japan, Hirayama, 1989: http://www.ncbi.nlm.nih.gov/pubmed/8059595
Italy, Filla, 1992: http://www.ncbi.nlm.nih.gov/pubmed/1512613
Italy, Leone, 1995: http://www.ncbi.nlm.nih.gov/pubmed/7793232
Portugal, Silva, 1997: http://www.jclinepi.com/article/S0895-4356(97)00202-3/abstract
The missing reference:
Italy, Lucci, 1982: Lucci B, Motti L, Guidetti D, Zucco R. Indagine epidemiologica descritiva delle eredoatassie nella provincia di Reggio-Emilia. In: Atti del III Convegno Nazionale di Neuroepidemiologia. 1982;p. 169–174
Tuesday, 26 July 2011
Symptons Update (walking technique 2) and new filming project.
I'm now finding that I'm having to spend more time concentrating on my walking style to avoid my feet tripping up. In the last couple of weeks whenever I'm walking I'm thinking "heel first" and trying to put my heel down before my toes.
I cant work out if I'm changing the way I bend my knee or changing the amount I lift my thigh on each step.
To see if I'm really changing I've also started filming my walking technique with the objective to record a "relaxed" and a "proper" walk every couple of weeks or so. Of course, its very difficult to "relax" properly when you know you are filming yourself, so we'll see how it pans out over the coming months.
I cant work out if I'm changing the way I bend my knee or changing the amount I lift my thigh on each step.
To see if I'm really changing I've also started filming my walking technique with the objective to record a "relaxed" and a "proper" walk every couple of weeks or so. Of course, its very difficult to "relax" properly when you know you are filming yourself, so we'll see how it pans out over the coming months.
Saturday, 16 July 2011
Trawl of SPG Variants
I have completed a bit of a trawl of the internet to find out the difference between the types of HSP/FSP. I've summarised this in the following table. The data is predominantly from these pages:
http://www.ncbi.nlm.nih.gov/books/NBK1509/
http://en.wikipedia.org/wiki/Hereditary_spastic_paraplegia
http://neuromuscular.wustl.edu/spinal/fsp.html
And various pages from this site: http://omim.org/entry/613206
Apologies if the table appears a little cumbersome, I used excel to save as a web-page, and then had to mess about with that a little further for it to work here in blogger-land.
I've only included data where I can find it, and I've tried not to re-interpret any data. There have been a couple of inconsistenceis between the sites I got the data from. Interestingly, there appear to be two different claims for SPG40. There are some other spastic paraplegias listed on some sites without SPG numbers. I've not include those here.
http://www.ncbi.nlm.nih.gov/books/NBK1509/
http://en.wikipedia.org/wiki/Hereditary_spastic_paraplegia
http://neuromuscular.wustl.edu/spinal/fsp.html
And various pages from this site: http://omim.org/entry/613206
Apologies if the table appears a little cumbersome, I used excel to save as a web-page, and then had to mess about with that a little further for it to work here in blogger-land.
I've only included data where I can find it, and I've tried not to re-interpret any data. There have been a couple of inconsistenceis between the sites I got the data from. Interestingly, there appear to be two different claims for SPG40. There are some other spastic paraplegias listed on some sites without SPG numbers. I've not include those here.
| SPG | pure/ complex | inheritance | onset | chromosonal locus | number mutations | type | bladder | bowel | speed | wheelchair | Epidemiology |
| 1 | complex | x-linked recessive | congenital | xq28 | Varied | ||||||
| 2 | complex | x-linked recessive | childhood-adolescence | Xq22 | Varied | yes | slow | ||||
| 3A | most pure | autosomnal dominant | ~6 | 14q11-q21 | >40 | Missence | some | 1/3 | slow | rare | |
| 4 | most pure | autosomnal dominant | ~29 | 2p22.3 | >250 | Varied | 34% | more rapid late onset | 17% | ||
| 5A | pure | autosomnal recessive | 1-20 | 8q12-q13 | >17 | Missense or Nonsense | 66% | some | Tunisian, American, Australian & British families | ||
| 5B | pure | autosomnal recessive | Tunisian family | ||||||||
| 6 | pure | autosomnal dominant | ~22 | 15q11.1 | Missence | 10% | Irish/Iraqui | ||||
| 7 | most pure | autosomnal recessive | 25-42 | 16q24.3 | 26 | Varied | 50% | rapid or slow | European, Moroccan & Turkish families | ||
| 8 | pure | autosomnal dominant | ~37 | 8q24.13 | Missence | 50% | 6 families | ||||
| 9 | complex | autosomnal dominant | childhood-adulthood | 10q23.3-q24.1 | Italian/British | ||||||
| 10 | both | autosomnal dominant | usuallt infancy/childhood | 12q13 | Missence/Other | 62% | moderate | 23% | |||
| 11 | most pure | autosomnal recessive | infancy-adolescene | 15q21.1 | >70 | Nonsense, Deletion & Insertion | most 1-2 decades after onset | North America, Europe, Japan, Turkey | |||
| 12 | pure | autosomnal dominant | ~7 | 19q13 | 33% | slow | within 4 years | Welsh/Italian | |||
| 13 | pure | autosomnal dominant | ~39 | 2q33.1 | Missence, Deletions | 14% | 2 families | ||||
| 14 | complex | autosomnal recessive | 30 | 3q27-q28 | slow | Italian family | |||||
| 15 | complex | autosomnal recessive | 13-23 | 14q23.3-q24.2 | Varied | yes | yes | 3-21 years | |||
| 16 | both | x-linked recessive | childhood | xq11.2 | Insertion | yes | yes | 1 family | |||
| 17 | complex | autosomnal dominant | adolescence-early adulthood | 11q13 | Missence | 18% | slow | >10 families | |||
| 18 | complex | autosomnal recessive | childhood | 8p12-p11.21 | 2 Omani families | ||||||
| 19 | pure | autosomnal dominant | 36-55 | 9q | 100% | slow | some | Italian family | |||
| 20 | complex | autosomnal recessive | childhood | 13q12.3 | Deletion | some | some | slow | 3rd-4th decade | Kuwait & Old Order Amish families | |
| 21 | complex | autosomnal recessive | 2nd and 3rd decade | 15q21-q22 | Insertion | slow | Ohio Amish | ||||
| 22 | complex | x-linked recessive | Xq21 | US families | |||||||
| 23 | complex | autosomnal recessive | childhood | 1q24-q32 | Arabian family | ||||||
| 24 | complex | autosomnal recessive | childhood | 13q14 | No | Saudi Arabian family | |||||
| 25 | complex | autosomnal recessive | 30-46 | 6q23-q24 | Italian family | ||||||
| 26 | complex | autosomnal recessive | 06-Nov | 12p11.1-q14 | slow | Kuwaiti family | |||||
| 27 | both | autosomnal recessive | 25-45 | 10q22.1-q24.1 | yes | slow | some | French-Canadian family | |||
| 28 | pure | autosomnal recessive | 6-15 | 14q21.3-q22.3 | Moroccan family | ||||||
| 29 | complex | autosomnal dominant | ~15 | 1p31.1-21.1 | 30% | 60% | Scottish family | ||||
| 30 | complex | autosomnal recessive | 12-21 | 2q37.3 | 50% | slow | Algerian origin family | ||||
| 31 | both | autosomnal dominant | childhood-young adulthood | 2p11.2 | Varied | some by 30-35 | >25 families mostly European | ||||
| 32 | complex | autosomnal recessive | 6-7 | 14q12-q21 | none | very slow | Potuguese family | ||||
| 33 | pure | autosomnal dominant | adulthood | 10q24.2 | Missence | slow | yes | German family | |||
| 34 | pure | x-linked recessive | late childhood | Xq25-q25 | none | none | 3-4 decades | Brazilian family | |||
| 35 | complex | autosomnal recessive | 4-11 | 16q21-q23.1 | yes | Omani and Pakistani families | |||||
| 36 | complex | autosomnal dominant | 24-30 | 12q23-q24 | yes | German family | |||||
| 37 | pure | autosomnal dominant | 32 | 8p21.1-q13.3 | 38% | French family | |||||
| 38 | autosomnal dominant | 17 | 4p16-p15 | Italian family | |||||||
| 39 | complex | autosomnal recessive | <7 | 19p13.3 | Missence, Frameshift insertion | yes | slow | Ashkenazi-Jewish & Northern European (German) families | |||
| 40 | pure | autosomnal dominant | 3q24-q26 | Chinese families | |||||||
| 40 | autosomnal dominant | Caucasian family | |||||||||
| 41 | pure | autosomnal dominant | 17 | 11p14.1-p11.2 | some | slow | Chinese family | ||||
| 42 | autosomnal dominant | first two decades | 3q24-q26 | Missence | None | Chinese family | |||||
| 43 | autosomnal recessive | 7-12 | 19p13.11-q12 | none | slow | Mali family | |||||
| 44 | complex | autosomnal recessive | 1st/2nd decades | 1q41-q42 | some | some | Italian family | ||||
| 45 | complex | autosomnal recessive | <1 | 10q24.3-q25.1 | Turkish famliy | ||||||
| 46 | complex | autosomnal recessive | 2-7 | 9p21.2-q21.12 | 50% | slow | Tunisian family | ||||
| 47 | complex | autosomnal recessive | 1p13.2-1p12 | Arabian family | |||||||
| 48 | autosomnal recessive | 49-50 | 7p22.1 | Varied | Yes | slow | French family |
Saturday, 25 June 2011
Another couple of useful web links
I was having a bit of a browse looking up various HSP info, and I found this one: http://emedicine.medscape.com/article/306713-overview. I like this because (a) it has lots of info presented and (b) the info it gives is written in a style I like. Therefore, it may also appeal to any regular readers here? There are lots more medical terms i need to look up and understand as well.
I also found this page: http://ghr.nlm.nih.gov/condition/spastic-paraplegia-type-4 which gives plenty of opportunities to get side-tracked clicking link after link after link...
I also found this page: http://ghr.nlm.nih.gov/condition/spastic-paraplegia-type-4 which gives plenty of opportunities to get side-tracked clicking link after link after link...
Friday, 10 June 2011
Symptoms Update, One Year In
Hi.
I realised that this post marks the start of my second year blogging, the first post being up in June 2010. So, a brief review of what I've discovered, and a comment about my symptoms.
In the last year I've found that there is a fair wedge of information about the condition out there, and that really the condition is a collective name for several different things. There's still lots that I dont know and so I endeavour to keep on searching out more information.
In terms of my symptoms, I posted a month or two ago that I've spotted my muscles becoming tight more frequently, and since then I've noticed this more often, and I'm having to 'force' my muscles to relax more and more. Also, I've found the last couple of weeks at Pilates more difficult than previously, and I wonder if I am now in the beginnings of the "Rapid Onset" of the condition proper. I feel that this might mean more symptoms updates from me going forwards.
I realised that this post marks the start of my second year blogging, the first post being up in June 2010. So, a brief review of what I've discovered, and a comment about my symptoms.
In the last year I've found that there is a fair wedge of information about the condition out there, and that really the condition is a collective name for several different things. There's still lots that I dont know and so I endeavour to keep on searching out more information.
In terms of my symptoms, I posted a month or two ago that I've spotted my muscles becoming tight more frequently, and since then I've noticed this more often, and I'm having to 'force' my muscles to relax more and more. Also, I've found the last couple of weeks at Pilates more difficult than previously, and I wonder if I am now in the beginnings of the "Rapid Onset" of the condition proper. I feel that this might mean more symptoms updates from me going forwards.
Saturday, 21 May 2011
Giving Blood
I give blood regularly. When I went to donate after I had had the genetic test there was a little uncertainty about if I could continue donating. But, fortunately, after some correspondence between the blood service and my genetics team, the blood service are happy for me to carry on donating blood even though I have the condition.
It will be interesting to see if this changes should I get prescribed anything to ease any condition symptoms in the future.
It will be interesting to see if this changes should I get prescribed anything to ease any condition symptoms in the future.
Monday, 9 May 2011
The differences between the types?
Todays thoughts revolve around the broad nature of the condition.
So, I have looked at the condition in types, of which there are two (see 25th Feb http://hspjourney.blogspot.com/2011/02/condition-in-types.html) and I mention the different HSP variants on 25th March (http://hspjourney.blogspot.com/2011/03/interpreting-genetic-test-results.html). I haven't looked into the different dominant/recessive/x-linked recessive variations either.
The different pages which describe the condition are fairly general about when people first get onset of the condition and are even more general about how severe the effects might be. For example, this page http://www.ncbi.nlm.nih.gov/books/NBK1509/ gives listing of various SPG variants (up to SPG33), and with each one there's a range of onset ages. I note that in July '10, SPG48 was identified http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.1000408.
I presume that that variation in severity is due to the amount of degradation in the nerves in the spinal column, but, I dont know the link between the particular SPG genetic modifications and the degradation of the nervous system - a topic for another post, perhaps. I am not surprised that there is variation in the condition given the ~50 variants, each with a range of onset age. I cannot decide if I should be surprised if 50 different variations give rise to the same broad symptoms though.
(However, if I think of potential reasons for my computer behaving slower at times, perhaps I should not be suprised, given the further complexity of the human body....)
So, I have looked at the condition in types, of which there are two (see 25th Feb http://hspjourney.blogspot.com/2011/02/condition-in-types.html) and I mention the different HSP variants on 25th March (http://hspjourney.blogspot.com/2011/03/interpreting-genetic-test-results.html). I haven't looked into the different dominant/recessive/x-linked recessive variations either.
The different pages which describe the condition are fairly general about when people first get onset of the condition and are even more general about how severe the effects might be. For example, this page http://www.ncbi.nlm.nih.gov/books/NBK1509/ gives listing of various SPG variants (up to SPG33), and with each one there's a range of onset ages. I note that in July '10, SPG48 was identified http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.1000408.
I presume that that variation in severity is due to the amount of degradation in the nerves in the spinal column, but, I dont know the link between the particular SPG genetic modifications and the degradation of the nervous system - a topic for another post, perhaps. I am not surprised that there is variation in the condition given the ~50 variants, each with a range of onset age. I cannot decide if I should be surprised if 50 different variations give rise to the same broad symptoms though.
(However, if I think of potential reasons for my computer behaving slower at times, perhaps I should not be suprised, given the further complexity of the human body....)
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