Mutation Screening and CGG-Repeat Distribution of the FMR1 gene Among Mentally Retarded and Autistic Patients in Algeriaby Aicha ZoubeidaBenmostefa, Dalila Satta, Noureddine Abadi, Isabel Creveaux, Algeria. lang='PT-BR' style='font-size:12.0pt;font-family:'Calibri','sans-serif'; mso-fareast-font-family:'Times New Roman';mso-ansi-language:PT-BR;mso-fareast-language: EN-US;mso-bidi-language:AR-SA;mso-bidi-font-weight

摘要

Fragile X syndrome (FXS) is the leading cause of inherited mental retardation. The underlying molecular alteration consists of a CGG- repeat expansion within the FMR1 gene. Therefore, searching for CGG expansion at the FXS locus among the mentally retarded should become a routine investigation in neuro-paediatric practice. This study was to establish a molecular diagnosis in Algerian patients exhibiting mental retardation with or without autistic features. It is important for the fragile X diagnosis to establish whether the range of allele distribution in Algerian patients are comparable to other populations, and if it is observed the same pattern of expansion associated with the disease. PCR was undertaken on 60 samples followed by Southern blot to analyze the CGG repeat number and methylation status. The molecular findings indicated in one young patient, diagnosed as autistic, mosaics mutations of 360 and 330 repetitions, while his mother was found carrying a premutated allele of 87 repetitions, and his two years old sister was found to have a contracted premutated allele of 63 repetitions of the CGG repeat. The distribution of the CGG repeats falls within the 30 repeats (17%), followed by a 31 repeat sizes (12%) instead of the 29 repeats as in the Caucasian population. The results of this study reconfirmed previous reports that the pattern of FMR1 CGG repeat alleles is different regarding the racial/ethnical population studied. In conclusion, the detection of the FXS mutations has allowed us to offer more informed genetic counseling and reliable patient follow-up.