Abstract
Presence of the human Y-chromosome in females with Turner Syndrome (TS) enhances the risk of development of gonadoblastoma besides causing several other phenotypic abnormalities. In the present study, we have analyzed the Y chromosome in 15 clinically diagnosed Turner Syndrome (TS) patients and detected high level of mosaicisms ranging from 45,XO:46,XY = 100:0% in 4; 45,XO:46,XY:46XX = 4:94:2 in 8; and 45,XO:46,XY:46XX = 50:30:20 cells in 3 TS patients, unlike previous reports showing 5–8% cells with Y- material. Also, no ring, marker or di-centric Y was observed in any of the cases. Of the two TS patients having intact Y chromosome in >85% cells, one was exceptionally tall. Both the patients were positive for SRY, DAZ, CDY1, DBY, UTY and AZFa, b and c specific STSs. Real Time PCR and FISH demonstrated tandem duplication/multiplication of the SRY and DAZ genes. At sequence level, the SRY was normal in 8 TS patients while the remaining 7 showed either absence of this gene or known and novel mutations within and outside of the HMG box. SNV/SFV analysis showed normal four copies of the DAZ genes in these 8 patients. All the TS patients showed aplastic uterus with no ovaries and no symptom of gonadoblastoma. Present study demonstrates new types of polymorphisms indicating that no two TS patients have identical genotype-phenotype. Thus, a comprehensive analysis of more number of samples is warranted to uncover consensus on the loci affected, to be able to use them as potential diagnostic markers.
Highlights
Turner Syndrome (TS), the common genetic abnormalities affecting,1 in 1500–2000 live female births [1,2,3], is suggested to be due to absence of the second X chromosome in part or full [3,4]
This mosaicism varies across the tissues and accurate interpretation depends upon the number of cells analyzed and tissues selected [12,13]
Turner Karyotypes and the Y chromosome TS patients analyzed were in the age group of 14–25 yrs
Summary
Turner Syndrome (TS), the common genetic abnormalities affecting ,1 in 1500–2000 live female births [1,2,3], is suggested to be due to absence of the second X chromosome in part or full [3,4]. In ,3–6% cells, the second sex chromosome is Y [5,6] that often triggers development of gonadoblastoma [7]. Chromosomal constitution influences phenotypic sex and 45, XO cell line is frequently detected in males with gonadal dysgenesis in addition to TS patients [10,11]. It is largely believed that no two TS patients are identical with respect to the number of Y bearing cells or Y-linked loci. This mosaicism varies across the tissues and accurate interpretation depends upon the number of cells analyzed and tissues selected [12,13]. Actual distribution of the Y chromosome in tissues of the TS patients and its role remain a murky proposition
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