Incomplete masculinisation of XX subjects carrying the SRY gene on an inactive X chromosome

46,XX subjects carrying the testis determining SRY gene usually have a completely male phenotype. In this study, five very rare cases of SRY carrying subjects (two XX males and three XX true hermaphrodites) with various degrees of incomplete masculinisation were analysed in order to elucidate the ca...

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Bibliographic Details
Published in:Journal of medical genetics 1999-06, Vol.36 (6), p.452-456
Main Authors: Kusz, Kamila, Kotecki, Maciej, Wojda, Alina, Szarras-Czapnik, Maria, Latos-Bielenska, Anna, Warenik-Szymankiewicz, Alina, Ruszczynska-Wolska, Anna, Jaruzelska, Jadwiga
Format: Article
Language:English
Subjects:
Ambiguity
Base Sequence
Biological and medical sciences
Disorders of Sex Development - genetics
DNA Primers - genetics
DNA-Binding Proteins - genetics
Dosage Compensation, Genetic
Female
Gynecology. Andrology. Obstetrics
Humans
In Situ Hybridization, Fluorescence
Lymphocytes
Male
Male and female genital diseases. Gonadal dysgenesis. Hermaphroditism. Sex hormones resistance
Males
Medical sciences
Nuclear Proteins
Original
Ovaries
Patients
Penis
Phenotype
sex determination
Sex Determination Processes
Sex-Determining Region Y Protein
Spermatogenesis
SRY gene
Testes
Testosterone
Transcription Factors
Translocation, Genetic
X Chromosome - genetics
X inactivation
Y Chromosome - genetics
Y chromosomes
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Summary:46,XX subjects carrying the testis determining SRY gene usually have a completely male phenotype. In this study, five very rare cases of SRY carrying subjects (two XX males and three XX true hermaphrodites) with various degrees of incomplete masculinisation were analysed in order to elucidate the cause of sexual ambiguity despite the presence of the SRY gene. PCR amplification of 20 Y chromosome specific sequences showed the Yp fragment to be much longer in XX males than in true hermaphrodites. FISH analysis combined with RBG banding of metaphase chromosomes of four patients showed that in all three true hermaphrodites and in one XX male the Yp fragment was translocated onto a late replicating inactive X chromosome in over 90% of their blood lymphocytes. However, in a control classical XX male with no ambiguous features, the Yp fragment (significantly shorter than in the XX male with sexual ambiguity and only slightly longer than in XX hermaphrodites) was translocated onto the active X chromosome in over 90% of cells. These studies strongly indicate that inactivation on the X chromosome spreading into a translocated Yp fragment could be the major mechanism causing a sexually ambiguous phenotype in XX (SRY+) subjects.
ISSN:0022-2593
1468-6244
DOI:10.1136/jmg.36.6.452