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Frequency and distribution of CGG/GCC repeats of FRAXA and FRAXE genes in South Indian non‐specific MR cases
Author(s) -
Katikala Lavanya,
Guruju Mallikarjuna,
Thelma B. K.,
Ramesh Om Sai,
Sujatha M.,
Anandaraj MPJS
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.782.26
Subject(s) - fragile x syndrome , fmr1 , trinucleotide repeat expansion , genetics , population , allele , biology , southern blot , gene , medicine , environmental health
Fragile X syndrome is one of the X‐linked disorders associated with moderate to severe mental retardation. Fragile X A syndrome (FRAXA) and fragile X E syndromes (FRAXE) are caused by trinucleotide expansions of CGG and GCC repeat expansion at the 5′ UTR of FMR1 and FMR2 genes respectively. Based on the number of the CGG repeats, individuals are classified into normal (5–60), permutated (60–200 repeats) and full mutated individuals (>200 repeats). We have screened 335 individuals from south India with MR of unknown etiology. All the individuals are clinically evaluated by a 15 item check list, molecular diagnosis was carried out using PCR and sizing of the amplicons were carried out by polyacrylamide gel electrophoresis. Of the 335 cases screened 12 unrelated cases positive for FRAXA. No cases of FRAXE have been identified. All Positive cases were confirmed by southern blotting using stb12.3 probe. Our study is the first study to report the frequency of FRAXE in south Indian population. We found the frequency of FRAXA to be 3.5 % and FRAXE to be 0%. Radioactive PCR is best to exactly estimate the allele sizes thereby finding the allelic variants in the population. We found 25 FRAXA and 20 FRAXE allelic variants in our population. The most frequent FRAXA allele size was 29 CGG repeats and that of FRAXE was 15 GCC repeats in South Indian non‐specific MR cases.