A fragile X family with high penetrance in females: risk heterogeneity?
A fragile X family is described which shows two interesting features. In a sibship of seven, the two males and four of the five females are affected with mental retardation. Since the only normal daughter is not a carrier, the penetrance of the fragile X mutation in carrier daughters is 100%. Nevertheless, the penetrance of this syndrome in affected daughters of normal mothers has been estimated at a third. Also, DNA typing analysis of flanking RFLP markers revealed a higher than expected number of crossing-overs. We also include the molecular study of the mutation in the (CGG)n repeat of the FMR-1 gene.
Martínez
F
F
Unidad de Genética y Diagnóstico Prenatal, Hospital Universitario La Fe, Valencia, Spain.
Badía
L
L
Prieto
F
F
D000293:Adolescent; D000328:Adult; D015139:Blotting, Southern; D003434:Crossing Over, Genetic; D004247:DNA / Q000032:analysis; D015342:DNA Probes; D004303:Dosage Compensation, Genetic; D005260:Female; D005600:Fragile X Syndrome / Q000175:diagnosis / Q000235:genetics*; D006579:Heterozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D010641:Phenotype; D012150:Polymorphism, Restriction Fragment Length
D015342:DNA Probes; D004247:DNA