ABSTRACT
BACKGROUND : Cytogenetics study using cultured T-lymphocytes derived from peripheral blood is the easiest way to study human chromosome complement and it is also an excellent method to study chromosomal abnormalities: either structural or numerical. The structural chromosomal abnormalities include translocations, deletions, duplications, ring chromosomes and isochromosomes. AIMS : Cases presenting with multiple congenital anomalies, mental retardation, pregnancy wastage or abnormalities in sexual function are referred to the Division of Human Genetics to rule out chromosomal anomalies. METHODS AND MATERIALS : A total of 70 cases with multiple congenital anomalies, mental retardation, pregnancy wastage or abnormalities in sexual function were studied. About 72 h cultured peripheral lymphocytes subjected to GTG banding were analyzed to look at the chromosome profile. RESULTS : Out of 70 cases of reciprocal translocation, single cell translocations were seen in ten cases (three females; seven males). Looking at the case profile, it was seen that they were referred for mental retardation, bad obstetric history and hypogonadism. It was seen that seven cases (70%) had t(7;14), two (20%) had complex translocations: t(X;9;8) and t(2;10;11), and one (10%) had t(4;21). CONCLUSIONS : Depending on the phenotype, the patients were informed of their abnormality and the need for a look out for the development of any associated problems.
ABSTRACT
Mental retardation due to fragile X syndrome is one of the genetic disorders caused by triplet repeat expansion. CGG repeat involved in this disease is known to exhibit polymorphism even among normal individuals. Here we describe the development of suitable probes for detection of polymorphism in CGG repeat at FMR1 locus as well as the diagnosis of fragile X syndrome. Using these methods polymorphism at the FMR1 locus has been examined in 161 individuals. Ninety eight patients with unclassified mental retardation were examined, of whom 7 were found to have the expanded (CGG) allele at the FMR1 locus. The hybridization pattern for two patients has been presented as representative data.