Síndrome frágil X: correlación clínica, citogenética y molecular en una familia

recent studies have allowed to characterize molecularly the genetic defect or fmr-1 mutation of the fragile x syndrome. this mutation consists in variations of repetitions of the gene's cgg triplet that came from the normal range to the complete mutation, passing through intermediate ranges or premutations. due to the fact that the affected individual also shows a variable percentage of xq27.3 fragile site (fraxa) in his karyotype, it is presented in this paper a clinical and cytogenetic correlation with the molecular characterization of the fmr-1 gen carried out by 2 direct methods: southern blot and polymerase chain reaction (pcr) in 5 affected males and 5 female carriers, one of them with prenatal diagnosis. the analysis of the clinical, physical and neuropsychological characterizations previously delineated, led to the conclusion that these, as well as the fraxa frequency in percentage, are correlated among the affected males with the elongation the mutation suffers on being transmitted from one generation to another through female carriers, in whom these characteristics are heterogeneous and susceptible to overlapping as a result of genomic effect and of environmental psychofamilial factors.