advertisement
Abstract #9127 Published in IGR 5-2
Mutations in MTMR13, a new pseudophosphatase homologue of MTMR2 and Sbf1, in two families with an autosomal recessive demyelinating form of Charcot-Marie-Tooth disease associated with early-onset glaucoma
Azzedine H; Bolino A; Taieb T; Birouk N; Di Duca M; Bouhouche A; Benamou S; Mrabet A; Hammadouche T; Chkili TAmerican Journal of Human Genetics 2003; 72: 1141-1153
Charcot-Marie-Tooth disease (CMT) with autosomal recessive (AR) inheritance is a heterogeneous group of inherited motor and sensory neuropathies. In some families from Japan and Brazil, a demyelinating CMT, mainly characterized by the presence of myelin outfoldings on nerve biopsies, cosegregated as an autosomal recessive trait with early-onset glaucoma. The authors identified two such large consanguineous families from Tunisia and Morocco with ages at onset ranging from two to 15 years. They mapped this syndrome to chromosome 11p15, in a 4.6-cM region overlapping the locus for an isolated demyelinating ARCMT (CMT4B2). In these two families, they identified two different nonsense mutations in the myotubularin-related 13 gene, MTMR13. The MTMR protein family includes proteins with a phosphoinositide phosphatase activity, as well as proteins in which key catalytic residues are missing and which are thus called 'pseudophosphatases'. MTM1, the first identified member of this family, and MTMR2 are responsible for X-linked myotubular myopathy and Charcot-Marie-Tooth disease type 4B1, an isolated peripheral neuropathy with myelin outfoldings, respectively. Both encode active phosphatases. It is striking to note that mutations in MTMR13 also cause peripheral neuropathy with myelin outfoldings, although it belongs to a pseudophosphatase subgroup, since its closest homologue is MTMR5/Sbf1. This is the first human disease caused by mutation in a pseudophosphatase, emphasizing the important function of these putatively inactive enzymes. MTMR13 may be important for the development of both the peripheral nerves and the trabeculum meshwork, which permits the outflow of the aqueous humor. Both these tissues have the same embryonic origin.
Dr. H. Azzedine, U289 INSERM, Assistance Publique-Hôpitaux de Paris, Groupe Hospitalier Pitie-Salpetriere, Paris, France
Classification:
1.2 Population genetics (Part of: 1 General aspects)
