CTG repeats distribution and Alu insertion polymorphism at myotonic dystrophy (DM) gene in Amhara and Oromo populations of Ethiopia.
Myotonic dystrophy (DM) is a dominantly inherited neuromuscular disease, highly variable and multisystemic, which is caused by the expansion of a CTG repeat located in the 3' untranslated region of the DMPK gene. Normal alleles show a copy number of 5-37 repeats on normal chromosomes, amplified to 50-3000 copies on DM chromosomes. The trinucleotide repeat shows a trimodal allele distribution in the majority of the examined population. The first class includes alleles carrying (CTG)5, the second class, alleles in the range 7-18 repeats, and the third class, alleles (CTG) > or =19. The frequency of this third class is directly related to the prevalence of DM in different populations, suggesting that normal large-sized alleles predispose toward DM. We studied CTG repeat allele distribution and Alu insertion and/or deletion polymorphism at the myotonic dystrophy locus in two major Ethiopian populations, the Amhara and Oromo. CTG allele distribution and haplotype analysis on a total of 224 normal chromosomes showed significant differences between the two ethnic groups. These differences have a bearing on the out-of-Africa hypothesis for the origin of the DM mutation. In addition, (CTG) > or =19 were exclusively detected in the Amhara population, confirming the predisposing role of these alleles compared with the DM expansion-mutation.
Gennarelli
M
M
Department of Biopathology and Diagnostic Imaging, Tor Vergata University of Rome and C.S.S.-Mendel Institute, Italy.
Pavoni
M
M
Cruciani
F
F
De Stefano
G
G
Dallapiccola
B
B
Novelli
G
G
D000483:Alleles; D020087:Alu Elements / Q000235:genetics*; D005002:Ethiopia; D006239:Haplotypes; D006801:Humans; D007585:Jews; D009223:Myotonic Dystrophy / Q000208:ethnology / Q000235:genetics*; D065636:Myotonin-Protein Kinase; D011110:Polymorphism, Genetic; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D018911:Trinucleotide Repeats
C585517:DMPK protein, human; D065636:Myotonin-Protein Kinase; D017346:Protein Serine-Threonine Kinases