Abicht, A. et al. A common mutation (1267delG) in congenital myasthenic patients of Gipsy ethnic origin. Neurology 53, 1564-1569
Genzentrum und Friedrich-Baur Institut, LMU München, Germany. Neurology
(Impact Factor: 8.29).
11/1999; 53(7):1564-9. DOI: 10.1212/WNL.53.7.1564
Mutation analysis of the acetylcholine receptor (AChR) epsilon subunit gene in patients with sporadic or autosomal recessive congenital myasthenic syndromes (CMS).
The nicotinic AChR of skeletal muscle is a neurotransmitter-gated ion channel that mediates synaptic transmission at the vertebrate neuromuscular junction. Mutations in its gene may cause congenital myasthenic syndromes. A recently described mutation in exon 12 of the AChR epsilon subunit (epsilon1267delG) disrupts the cytoplasmic loop and the fourth transmembrane region (M4) of the AChR epsilon subunit.
Forty-three CMS patients from 35 nonrelated families were clinically classified as sporadic cases of CMS (group III according to European Neuromuscular Centre consensus) and were analyzed for epsilon1267delG by PCR amplification and sequence analysis.
The authors report the complete genomic sequence and organization of the gene coding for the epsilon subunit of the human AChR (accession number AF105999). Homozygous epsilon1267delG was identified in 13 CMS patients from 11 independent families. All epsilon1267delG families were of Gypsy or southeastern European origin. Genotype analysis indicated that they derive from a common ancestor (founder) causing CMS in the southeastern European Gypsy population. Phenotype analysis revealed a uniform pattern of clinical features including bilateral ptosis and mild to moderate fatigable weakness of ocular, facial, bulbar, and limb muscles.
The mutation epsilon1267delG might be frequent in European congenital myasthenic syndrome patients of Gypsy ethnic origin. In general, patients (epsilon1267delG) were characterized by the onset of symptoms in early infancy, the presence of ophthalmoparesis, positive response to anticholinesterase treatment, and the benign natural course of the disease.
Available from: Francesc Calafell
- "• Limb girdle muscular dystrophy type 2C in France, Spain, Italy, Germany , Portugal  and Bulgaria [65,66,93]. • Congenital myasthenia in Serbia, Macedonia, Greece, Bohemia and Germany . • Hereditary motor and sensory neuropathy - Russe in Bulgaria , Romania and Spain [our unpublished findings]. "
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ABSTRACT: BackgroundData provided by the social sciences as well as genetic research suggest that the 8-10 million Roma (Gypsies) who live in Europe today are best described as a conglomerate of genetically isolated founder populations. The relationship between the traditional social structure observed by the Roma, where the Group is the primary unit, and the boundaries, demographic history and biological relatedness of the diverse founder populations appears complex and has not been addressed by population genetic studies.ResultsRecent medical genetic research has identified a number of novel, or previously known but rare conditions, caused by private founder mutations. A summary of the findings, provided in this review, should assist diagnosis and counselling in affected families, and promote future collaborative research. The available incomplete epidemiological data suggest a non-random distribution of disease-causing mutations among Romani groups.ConclusionAlthough far from systematic, the published information indicates that medical genetics has an important role to play in improving the health of this underprivileged and forgotten people of Europe. Reported carrier rates for some Mendelian disorders are in the range of 5 -15%, sufficient to justify newborn screening and early treatment, or community-based education and carrier testing programs for disorders where no therapy is currently available. To be most productive, future studies of the epidemiology of single gene disorders should take social organisation and cultural anthropology into consideration, thus allowing the targeting of public health programs and contributing to the understanding of population structure and demographic history of the Roma.
Available from: David Beeson
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ABSTRACT: Congenital myasthenic syndromes are a clinically and genetically heterogeneous group of hereditary disorders affecting neuromuscular
transmission. We have identified mutations within the acetylcholine receptor (AChR) ε-subunit gene underlying congenital myasthenic
syndromes in nine patients (seven kinships) of Dutch origin. Previously reported mutations ε1369delG and εR311Q were found
to be common; ε1369delG was present on at least one allele in seven of the nine patients, and εR311Q in six. Phenotypes ranged
from relatively mild ptosis and external ophthalmoplegia to generalized myasthenia. The common occurrence of εR311Q and ε1369delG
suggests a possible founder for each of these mutations originating in North Western Europe, possibly in Holland. Knowledge
of the ethnic or geographic origin within Europe of AChR deficiency patients can help in targeting genetic screening and it
may be possible to provide a rapid genetic diagnosis for patients of Dutch origin by screening first for εR311Q and ε1369delG.
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