[The use of FISH on buccal smear to investigate mosaicism with a 45,X cell line: study on healthy men and patients with disorders of sex development].

Objective: To verify whether fluorescence in situ hybridization (FISH) of cells from the buccal epithelium could be employed to detect cryptomosaicism with a 45,X lineage in 46,XY patients.

Subjects And Methods: Samples of nineteen 46,XY healthy young men and five patients with disorders of sex development (DSD), four 45,X/46,XY and one 46,XY were used. FISH analysis with X and Y specific probes on interphase nuclei from blood lymphocytes and buccal epithelium were analyzed to investigate the proportion of nuclei containing only the signal of the X chromosome.

Screening of Y chromosome microdeletions in 46,XY partial gonadal dysgenesis and in patients with a 45,X/46,XY karyotype or its variants.

Background: Partial and mixed gonadal dysgenesis (PGD and MGD) are characterized by genital ambiguity and the finding of either a streak gonad and a dysgenetic testis or two dysgenetic testes. The karyotype in PGD is 46,XY, whereas a 45,X/46,XY mosaicism or its variants (more than two lineages and/or structural abnormalities of the Y chromosome) is generally found in MGD. Such mosaics are also compatible with female phenotype and Turner syndrome, ovotesticular disorder of sex development, and infertility in men with normal external genitalia.

The use of fluorescence in situ hybridization in the diagnosis of hidden mosaicism: apropos of three cases of sex chromosome anomalies.

FISH has been used as a complement to classical cytogenetics in the detection of mosaicism in sex chromosome anomalies. The aim of this study is to describe three cases in which the final diagnosis could only be achieved by FISH. Case 1 was an 8-year-old 46,XY girl with normal female genitalia referred to our service because of short stature.