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PO.04 Ethnic variation in GLRA1 genotype in hyperekplexia
  1. R Thomas1,
  2. S K Chung2,
  3. C L Hammond2,
  4. A Robinson2,
  5. M I Rees2
  1. 1Department of Neurology, UK
  2. 2College of Medicine, Institute of Life Science, Swansea University, United Kingdom

Abstract

Introduction Mutations in the alpha one subunit of the glycine receptor (GLRA1) cause the majority of genetic (hereditary) hyperekplexia. Three-quarters of cases show autosomal recessive inheritance and some ethic variation has been described.

Methods We undertook a review of all published cases of hyperekplexia with a genetic cause alongside mutations identified as part of our research. Ethnicities were defined by the referring clinician and then subgrouped into five categories—Caucasian, Asian, Arabic, Turkish and Afro-American.

Results 37/53 cases from the literature had a published ethnicity; we included an additional thirty unpublished cases. Homozygous deletions of exons one to six are exclusively seen in people of Turkish descent (n=12, p<0.00001). In contrast mutations of the arginine residue at point 271 are seen in people of Asian, Caucasian and African-American heritage (n=15) but not yet in people with Arab or Turkish ethnicities (p<0.0005). Some backgrounds had no published cases yet—including Polynesian, Slavic and North African heritage.

Conclusion No clear founder effect was seen in R271 cases. Hyperekplexia does show regional and ethnic variation but is it present but recognised in populations where it is less prevalent? Hyperekplexia due to R271 mutations shows dominant inheritance and the deletions of exons one to six are recessive; meaning that the inheritance pattern can be in part predicted by someone's estimated ethnicity.

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