45,X/46,X,idic(Yq) mosaicism: Clinical, cytogenetic, and molecular studies in four individuals

Abstract

45,X/46,X,idic(Yq) mosaicism is associated with a variety of sex phenotypes, including Ullrich-Turner syndrome (UTS), intersexuality, and complete male. It remains unclear whether the phenotypic variability results from a dilutional effect by the 45,X cell line in the primordial gonad or an abnormality of the SRY gene (SRY). We conducted cytogenetic and molecular studies on four patients with such mosaicism, two of whom had a complete male phenotype and two who had UTS. Chromosome analyses showed that the frequency of cells carrying an idic(Yq) chromosome in peripheral blood lymphocytes and skin fibroblasts was not related to the given sex phenotype. The SRY, PABY, and ZFY genes were present in all four patients. A fluorescence in situ hybridization (FISH) study showed that both a patient with a complete male phenotype and another with UTS had duplicate copies of SRY in their idic(Yq) chromosomes, whereas a patient with UTS had a single copy of the gene. These findings suggested that the coexisting 45,X cell line is more influential on the determination of the sex phenotype in individuals with 45,X/ 46,X,idic(Yq) mosaicism.

Clinical, cytogenetic, and molecular findings of isodicentric Y chromosomes

“…In our study, only one of the six patients had a nonmosaic karyotype, and a 45,X cell line was most common form of mosaicism. These findings are consistent with most isodicentric Y chromosome cases reported [4, 11, 14, 25–29]. There are also many other aberrant chromosomes that could arise with isodicentric Y chromosomes, leading to a very complicated karyotype [3, 4, 17, 30–32].…”

“…Thus, it is extremely important to identify this Y chromosome aberration prenatally to provide genetic counselling and interpretation. Previous studies have applied conventional karyotype analysis, FISH, Southern blot, and sequence-tagged site (STS) PCR to identify isodicentric Y chromosomes and the breakpoints contained within them [14, 15]. Other techniques, such as multiplex ligation-dependent probe amplification (MLPA), qPCR, CMA, and the sequencing of certain genes, have also been used to gain molecular insight into isodicentric Y chromosomes [16–18].…”

MgCl2‐supported catalyst containing mixed internal donors for propylene polymerization

“…The reason for such a diversity is not completely clear. The relative importance of the presence or absence in the idic(Y) chromosome of certain genes, particularly SRY , and of the proportion of 45,X cells distributed over the different tissues, mainly in the gonads, has been discussed for at least two decades [Daniel, 1985; Teraoka et al, 1998; Morava et al, 2000]. Careful evaluation of such cases has contributed to a better understanding of the sex determination process.…”

Startling Mosaicism of the Y-Chromosome and Tandem Duplication of the SRY and DAZ Genes in Patients with Turner Syndrome

“…The Y chromosome in Turner patients is structurally abnormal showing deletions, inversions, dicentrics and ring forms [8] – [9] and becomes unstable resulting in 45/XO karyotype. 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.…”