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A newborn with ambiguous genitalia and a complex X;Y rearrangement.

ABSTRACT: BACKGROUND:In most mammals, sex is determined at the beginning of gestation by the constitution of the sex chromosomes, XY in males and XX in females. CASE:Here we report an interesting case characterized by ambiguous genitalia and ovotestis in a newborn carrying an apparently female karyotype (46 XX). Array Comparative Genomic Hybridization (Array-CGH) revealed an unbalanced rearrangement resulting in the deletion of the distal Xp and the duplication of the proximal Xp contiguous region with presence of the Y chromosome from Ypter to Yq11. Fluorescent in situ hybridization (FISH) showed that this portion of the Y was translocated to the tip of the abnormal X and that the duplicated portion of chromosome X was inverted. Altogether, the abnormal chromosome was a dicentric one with the centromere of the Y chromosome apparently inactivated. CONCLUSION:The presence within the translocated Y chromosome of the SRY gene explains the devolopment of testes although it is not clear the reason for the genitalia ambiguity.

SUBMITTER: Dehghani M

PROVIDER: S-EPMC4094661 | biostudies-literature | 2014 May

REPOSITORIES: biostudies-literature

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A newborn with ambiguous genitalia and a complex X;Y rearrangement.

Dehghani Mohammadreza M Rossi Elena E Vetro Annalisa A Russo Gianni G Hashemian Zahra Z Zuffardi Orsetta O

Iranian journal of reproductive medicine 20140501 5

<h4>Background</h4>In most mammals, sex is determined at the beginning of gestation by the constitution of the sex chromosomes, XY in males and XX in females.<h4>Case</h4>Here we report an interesting case characterized by ambiguous genitalia and ovotestis in a newborn carrying an apparently female karyotype (46 XX). Array Comparative Genomic Hybridization (Array-CGH) revealed an unbalanced rearrangement resulting in the deletion of the distal Xp and the duplication of the proximal Xp contiguous ...[more]

PMID: 25031580

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Project description:BackgroundTurner syndrome, a congenital condition that affects 1/2,500 births, results from absence or structural alteration of the second sex chromosome. Turner syndrome is usually associated with short stature, gonadal dysgenesis and variable dysmorphic features. The classical 45,X karyotype accounts approximately for half of all patients, the remainder exhibit mosaicism or structural abnormalities of the X chromosome. However, complex intra-X chromosomal rearrangements involving more than three breakpoints are extremely rare.ResultsWe present a unique case of a novel complex X chromosome rearrangement in a young female patient presenting successively a wide range of autoimmune diseases including insulin dependent diabetes mellitus, Hashimoto's thyroiditis, celiac disease, anaemia perniciosa, possible inner ear disease and severe hair loss. For the genetic evaluation, conventional cytogenetic analysis and FISH with different X specific probes were initially performed. The complexity of these results and the variety of autoimmune problems of the patient prompted us to identify the exact composition and breakpoints of the rearranged X as well as methylation status of the X chromosomes. The high resolution array-CGH (assembly GRCh37/hg19) detected single copy for the whole chromosome X short arm. Two different sized segments of Xq arm were present in three copies: one large size of 80,3 Mb from Xq11.1 to Xq27.3 region and another smaller (11,1 Mb) from Xq27.3 to Xq28 region. An 1,6 Mb Xq27.3 region of the long arm was present in two copies. Southern blot analysis identified a skewed X inactivation with ≈ 70:30 % ratios of methylated/unmethylated fragments. The G-band and FISH patterns of the rearranged X suggested the aspect of a restructured i(Xq) chromosome which was shattered and fortuitously repaired. The X-STR genotype analysis of the family detected that the patient inherited intact maternal X chromosome and a rearranged paternal X chromosome. The multiple Xq breakages and fusions as well as inverted duplication would have been expected to cause a severe Turner phenotype. However, the patient lacks many of the classic somatic features of Turner syndrome, instead she presented multiorgan autoimmune diseases.ConclusionsThe clinical data of the presented patient suggest that fragmentation of the i(Xq) chromosome elevates the risk of autoimmune diseases.

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A newborn with ambiguous genitalia and a complex X;Y rearrangement.

Publications

A newborn with ambiguous genitalia and a complex X;Y rearrangement.

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