Thesis (Selection of subject)Thesis (Selection of subject)(version: 336)
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Molekulárně genetická a klinicko-neurologická vyšetření u autozomálně recesivních forem dědičných neropatií Charcot-Marie-Tooth
Thesis title in Czech: Molekulárně genetická a klinicko-neurologická vyšetření u
autozomálně recesivních forem dědičných neropatií Charcot-Marie-Tooth
Thesis title in English: Molecular genetic and clinical neurological exmaination in autosomal recessive
forms of hereditary neuropathies Charcot-Marie-Tooth
Academic year of topic announcement: 2010/2011
Type of assignment: dissertation
Thesis language: čeština
Department: Department of Neurology (13-442)
Supervisor: prof. MUDr. Martin Bojar, CSc.
Author: hidden - assigned and confirmed by the Study Dept.
Date of registration: 22.06.2010
Date of assignment: 22.06.2010
Date and time of defence: 06.12.2010 14:00
Date of electronic submission:22.06.2010
Date of submission of printed version:22.06.2010
Date of proceeded defence: 06.12.2010
Reviewers: prof. MUDr. Pavel Martásek, DrSc.
  MUDr. Stanislav Voháňka, CSc., MBA
 
 
References
Ammar N, Nelis E, Merlini L, Barisić N, Amouri R, Ceuterick C, Martin JJ, Timmerman V, Hentati F, De Jonghe P. Identification of novel GDAP1 mutations causing autosomal recessive Charcot-Marie-Tooth disease. Neuromuscul Disord. 2003;13:720-8
Angelicheva D, Turnev I, Dye D, Chandler D, Thomas PK, Kalaydjieva L. Congenital cataracts facial dysmorphism neuropathy (CCFDN) syndrome: a novel developmental disorder in Gypsies maps to 18qter. Eur J Hum Genet. 1999;7:560-6
Azzedine H, Ruberg M, Ente D, Gilardeau C, Périé S, Wechsler B, Brice A, LeGuern E, Dubourg O. Variability of disease progression in a family with autosomal recessive CMT associated with a S194X and new R310Q mutation in the GDAP1 gene. Neuromuscul Disord. 2003;13:341-6
Barhoumi C, Amouri R, Ben Hamida C, Ben Hamida M, Machghoul S, Gueddiche M, Hentati F. Linkage of a new locus for autosomal recessive axonal form of Charcot-Marie-Tooth disease to chromosome 8q21.3. Neuromuscul Disord. 2001;11:27-34
Baxter RV, Ben Othmane K, Rochelle JM, Stajich JE, Hulette C, Dew-Knight S, Hentati F, Ben Hamida M, Bel S, Stenger JE, Gilbert JR, Pericak-Vance MA, Vance JM.Ganglioside-induced differentiation-associated protein-1 is mutant in Charcot-Marie-Tooth disease type 4A/8q21. Nat Genet. 2003;30:21-2
Ben Othmane K, Hentati F, Lennon F, Ben Hamida C, Blel S, Roses AD, Pericak-Vance MA, Ben Hamida M, Vance JM.Linkage of a locus (CMT4A) for autosomal recessive Charcot-Marie- Tooth disease to chromosome 8q. Hum Mol Genet. 1993;2:1625-8
Varon R, Gooding R, Steglich C, Marns L, Tang H, Angelicheva D, Yong KK, Ambrugger P, Reinhold A, Morar B, Baas F, Kwa M, Tournev I, Guerguelcheva V, Kremensky I, Lochmüller H, Müllner-Eidenböck A, Merlini L, Neumann L, Bürger J, Walter M, Swoboda K, Thomas PK, von Moers A, Risch N, Kalaydjieva L.Partial deficiency of the C- terminal-domain phosphatase of RNA polymerase II is associated with congenital cataracts facial dysmorphism neuropathy syndrome. Nat Genet. 2003;35:185-9
Züchner S, Noureddine M, Kennerson M, Verhoeven K, Claeys K, De Jonghe P, Merory J, Oliveira SA, Speer MC, Stenger JE, Walizada G, Zhu D, Pericak-Vance MA, Nicholson G, Timmerman V, Vance JM. Mutations in the pleckstrin homology domain of dynamin 2 cause dominant intermediate Charcot-Marie-Tooth disease. Nat Genet. 2005;37:289-94
Züchner S and Vance M. Molecular genetics of autosomal-dominant axonal Charcot-Marie-Tooth disease. Neuromolecular Med. 2006;8:63-74
http://www.molgen.ua.ac.be/CMTMutations/
http://www.gdb.org/
Preliminary scope of work
Cíle studie
V rozsáhlém souboru CMT rodin žijících v České republice v registru DNA laboratoře Kliniky dětské neurologie 2. LF UK a FNM nebyla po vyšetření na dosud známé tři nejčastější příčiny CMT (duplikace PMP22 genu, mutace v MPZ a GJB1 genu) přibližně u poloviny genetická příčina nalezena. Soubor k dubnu 2007 zahrnoval 1150 rodin. Tato studie se zaměřila na AR geny, které zatím nebyly v naší laboratoři testovány. Geny GDAP1 a PRX byly vybrány na základě záchytu mutací v jiných populacích (http://www.molgen.ua.ac.be/CMTMutations). Studie měla cíle:
• zjistit relativní zastoupení jednotlivých typů dědičnosti v dosud shromážděném souboru CMT rodin v České republice, především podíl autosomálně recesivních (AR) rodin a rodin se sporadickým výskytem CMT.
• detekovat patogenní mutace v genech PRX a GDAP1 u vybraných CMT pacientů z rodin s AR rodokmenem a z rodin se sporadickým výskytem onemocnění.
• zjistit frekvence výskytu mutací v genech PRX a GDAP1 mezi testovanými pacienty, jejich spektrum a zjistit případné prevalentní mutace v české populaci.
• upřesnit neurologický a elektrofyziologický obraz u CMT4F a CMT4A (CMT4C4) pacientů.
• navrhnout algoritmus molekulárně-genetického vyšetření pacientů v ČR na typy CMT4F a CMT4A (CMT4C4).
Preliminary scope of work in English
The Charcot-Marie–Tooth (CMT) diseases are the most common inherited neuropathies. CMT is characterized clinically by distal muscle wasting and weakness, reduced reflexes and impaired distal sensation and by a sensory motor neuropathy neurophysiologically. The severity of the disease varies enormously depending to a large extent on the underlying genetic defect. The current clinical classification of CMT is done using electrophysiological criteria into type 1 (demyelinating) and type 2 (axonal) and further sub-classification is done according to inheritance pattern. A solely genetic classsification is not possible at present as all the causative genes for CMT are not known.
Autosomal recessive CMT (AR CMT) forms are rare in European populations. The responsible genes have been discovered just in recent years. The disease has usually early onset and fast progressing and severe course. Mutations in GDAP1 gene (ganglioside- induced differentation associated proteine-1) soon showed to be the most common cause of CMT in families with AR pedigrees. They were found in patients with demyelinating (CMT4A) as well as axonal (CMT4C4) CMT. Common GDAP1 mutations are consquence of founder effect. Mutations in PRX (periaxin) gene are responsible for demyelinating CMT type (CMT4F).
Approximately in a half of the CMT families living in the Czech Republic from a unique CMT database of DNA laboratory of Department of Child Neurology , 2nd School of Medicine, Charles University Prague, the underlying genetic cause after testing for the most common CMT causes remained unknown. The aims of the study was to detect pathogenic mutations in GDAP1 a PRX genes in selected patients from AR CMT families and families with isolated CMT cases, to test prevalent mutations for founder effect and to give detailed clinical and electrophysiological phenotype in patients with the identified mutations. It was believed that the results of the study could contribute to make the molecular genetic testing of AR CMT forms in the Czech Republic more effective.
We sequenced GDAP1 in 74 patients from 69 unrelated families with early-onset demyelinating or axonal CMT compatible with AR inheritance. For PRX we sequenced 59 patients from 55 families including four unrelated Romani patients with early-onset CMT displaying decreased nerve conduction velocities. The haplotype analysis for a prevalent L239F mutation was performed.
We identified three isolated patients with GDAP1 mutations in both alleles. In one additional sporadic and one familial case, the second pathogenic mutation remained unknown. Overall, we detected two different mutations, a novel R191X nonsense and a L239F missense mutation. L239F previously described in a German-Italian family is prevailing in Czech population and we give evidence for its common ancestral origin. All Czech GDAP1 patients developed involvement of all four limbs except of one by the end of second decade. However, L239F homozygotes displayed less severe impairment compared to homozygotes for common mutations Q163X and S194X. All patients displayed axonal type of neuropathy.
In PRX gene we identified a novel homozygous mutation c.3286_3356del71 (K1095fsX18) in one Romani patient showing very slow disease progression. It is the first PRX mutation detected in Romani population. It is the most downstream located mutation detected so far that shortens periaxin by an acidic domain. This finding supports pathogenetic role of the domain missing proposed by former studies. Amongst Czech CMT patients PRX mutations have been proven very rare.
The study came to the following conclusions. For PRX gene testing, Romani patients with demyelinating CMT will be selected. The gene, on the other hand, will not be involved in routine molecular genetic examination of Czech CMT patients. GDAP1 gene examination will be included in routine testing of selected patients with axonal CMT from families with AR inheritance pattern as well as isolated CMT cases. We will target the testing to exons 4 and 6, where the detected mutations lie. We suggest starting CMT testing of patients from European populations for the L239F mutation.
 
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