Short Stature on a Boy: Mosaicism with an Isodicentric Y Chromosome

A mosaic karyotype of 45,X/46,X,psu idic(Y)(q12) in a ten-year-old boy: integrating high-throughput sequencing with cytogenetic technique for precise diagnosis and genetic counselling

BACKGROUND

Isodicentric Y chromosome (idic(Y)) is the most commonly reported aberration of the human Y chromosome, which is an important cause of abnormal sexual development. The breakpoints of isodicentric Y chromosome mostly occurred in Yq11.2 and Yp11.3, however, the breakpoints in Yq12 are relatively rare.

CASE PRESENTATION

We described a 10-year-old boy presenting hypospadias, micropenis and short stature, as well as unilateral cryptorchidism without normal testicular seminiferous tubules structure by biopsy. Whole exome sequencing didn't find any pathogenic/likely pathogenic variants related to phenotypes of this patient. Copy number variation sequencing showed the duplication of whole Y chromosome. Subsequently, karyotyping and FISH analyses demonstrated his genetic diagnosis was mosaic 45,X[8]/46,X,psu idic(Y)(q12)[32], with the breakpoint in Yq12.

CONCLUSIONS

Our case proved that it would be beneficial to integrate high-throughput sequencing with cytogenetic technique for precise diagnosis, treatment and genetic counselling.

Clinical, cytogenomic, and molecular characterization of isodicentric Y-chromosome and prediction of testicular sperm retrieval outcomes in azoospermic and severe oligozoospermic infertile men

PURPOSE

Sex chromosome abnormalities are associated with male infertility. The aim of this study was to characterize the clinical, cytogenetic, and molecular findings of 12 infertile men with isodicentric Y-chromosome [idic(Y)] abnormalities diagnosed over a period of 13 years.

MATERIALS AND METHODS

Chromosomal analyses of peripheral blood samples were done using standard procedures. Fluorescence in situ hybridization (FISH) analysis was performed on metaphase spreads of the patients. Multiplex polymerase chain reaction (PCR) using several sequence-tagged site (STS) primer sets within the long arm of Y-chromosome was used to detect AZF deletions.The breakpoints and copy number variations (CNV) were identified by array comparative genomic hybridization analysis (aCGH) analysis.The short-stature homeobox (SHOX) gene deletions were verified using multiplex ligation-dependent probe amplification (MLPA) analysis.

RESULTS

Twelve infertile men were diagnosed cytogenetically with idic(Y). The karyotypes of two of the patients were non-mosaic, and the remaining karyotypes showed various degrees of mosaicism. SHOX gene deletion was found in two of the four patients with short stature, and the remaining two patients had shown a 45,X dominant cell line (33.3%). The most common breakpoints for idic(Yq) and idic(Yp) were found to be in Yq11.222 and Yp11.32, respectively. Semen analysis of ten patients (83.3%) demonstrated azoospermia, and the remaining two patients (16.7%) showed severe oligoasthenoteratozoospermia (OAT). In total, 33% (4/12) of idic(Y) patients with or without microsurgical testicular sperm extraction (microTESE) had sperm retrieval.

CONCLUSIONS

Twelve patients with idic(Y) and different breakpoints of Y-chromosome were characterized using multiple detection strategies. Sperm retrieval outcomes of patients either with idic(Yp) or idic(Yq) showed the possibility to find sperm by microTESE.

Can Boys Have Turner Syndrome? More than a Question of Semantics

Individuals with 45,X mosaicism with Y chromosome material raised as boys are not diagnosed with Turner syndrome, a label restricted to phenotypic females. We sought to determine if boys with 45,X mosaicism had features consistent with Turner syndrome. Twenty-two patients (14 girls, 8 boys) seen in our Differences of Sex Development (DSD) clinic were identified for review. Standardized height (z-scores) by sex of rearing and results of cardiology, renal, audiology, thyroid, and celiac screenings were recorded. All subjects had heights below the mean for sex. Z-scores were not significantly different between boys and girls (p = 0.185). There were no significant differences in the incidence of cardiac anomalies between boys and girls (p = 0.08). Girls were more likely to have additional screenings (p = 0.042), but there were no significant differences in the number of positive screenings between boys and girls (p = 0.332). Patients with 45,X mosaicism raised as boys appear to have features similar to patients with the same karyotype raised as girls. Routine screening of boys following the Turner Syndrome Clinical Practice Guidelines may allow early recognition of comorbidities. Additionally, obtaining karyotypes on boys with short stature or other features of Turner syndrome may identify unrecognized cases of 45,X mosaicism.

Gender-Discordant Monochorionic-Diamniotic Twins Both With 45,X/46,X, Idic(Y) Mosaicism and a Novel Deletion Within the TBC1D5 Gene

The occurrence of monochorionic diamniotic twins with sex discordance is a very rare phenomenon. We present a case of spontaneously conceived gender-discordant monochorionic diamniotic twins born to a 23-year-old female, both twins demonstrating similar blood karyotype 45,X/46,X, idic(Y) and a novel 99 kb mutation at 3p24.3 involving exons 15-16 of transcript NM_001134381.1 of the Tre-2/Bub2/Cdc16 Domain Family Member 5 (TBC1D5) gene. The male twin showed no anatomic abnormalities and pelvic ultrasound revealed descended gonads. The female twin had a horseshoe-shaped kidney, normal uterus, and intra-abdominal gonads. The blood karyotype and microarray studies revealed similar distribution of X and isodicentric Y chromosome along with a novel genetic mutation which has not been previously reported. Our case findings not only report Turner syndrome mosaicism with a novel genetic mutation but also stress the importance of clinical follow-up of twins in order to evaluate the functional abnormalities associated with isodicentric Y chromosomes including germ cell tumors.