[Familial chromosome X structural aberrations - case report].

UNLABELLED: The X chromosome contains about 1000 genes with different functions, both general and specialized, among which are genes responsible for normal function of the ovaries in women and normal growth in both sexes. Patients with chromosome X aberrations present a large spectrum of phenotypes depending on a variable size of chromosome X regions which are involved in aberrations, differences in genes located in/around given break-points, number of X chromosomes in cells and preferential X inactivation. We report on two families diagnosed with chromosome X aberration. The familial dupXq/delXp and the familial Xp deletion were diagnosed using GTG-banding techniques and confirmed by FISH analysis. In both families chromosome X aberrations were observed in healthy, fertile women, without a history of recurrent miscarriages or mentally retarded children. In one of the cases (family A) a mother with a mosaic X chromosome aberration [mos 45,X/46,X,der(X)(qter→q2? 7::p22.2→qter)], with previously undiagnosed Turner's syndrome, gave birth to her third daughter with a karyotype that contained only the structural X chromosome aberration, of maternal origin [46,X,der(X)(qter→q2? 7::p22.2→→ qter).ish der(X) (wcpX+, pter-, KAL-, qter++]. In the second case (family B) a mother [46,X,del(X)(p22.1p22.2).ish del(X)(wcpX+, pter+, KAL-, qter+)] gave birth to a girl with Down syndrome (21 trisomy), who has also had an additional chromosome X aberration [47,X,del(X)(p22.1p22.2),+21.ish del(X)(wcpX+, pter+, KAL-, qter+)].

CONCLUSIONS

Chromosome X aberrations found in women may sometimes not influence the incidence of phenotypic abnormalities and their fertility. In such cases, the diagnosis usually occurs incidentally.