Prenatal identification of an isochromosome for the short arm of the Y i(Yp), by cytogenetic and Molecular analyses

Abstract

A case of 45,X/46,X,+mar mosaicism was detected in a male fetus (27 weeks' gestation) referred for karyotype analysis following the observation of a short femur at the ultrasound scan. Analysis of 12 Y-chromosome loci by fluorescent in situ hybridization (FISH) and polymerase chain reaction (PCR) demonstrated that the marker chromosome is of Y origin and corresponds to an authentic isochromosome for the short arm of the Y chromosome, i(Yp). The breakpoint on this marker is in YQ11.1 close to the centromere. The present report illustrates the importance of FISH and PCR techniques as a complement to cytogenetic methods for accurate identification and characterization of chromosome rearrangements in prenatal diagnosis.

Prenatal identification of i(YP) by molecular cytogenetic analysis

“…Prenatal detection of a de novo i(Yp) presents a diagnostic dilemma, since its impact on fetal and postnatal development is difficult to predict. The majority of reported cases with i(Yp) have involved 45,X/46,X,+mar mosaicism (Slim et al, 1994). The phenotypic expression in such cases ranges from females with sexual ambiguity andor Turner stigmata to phenotypically normal males.…”

“…An isochromosome derived from the short arm of the Y chromosome [iCyp)] is an uncommon marker chromosome. In the majority of cases, individuals with a 46,X,i(Yp) appear to be phenotypically normal (albeit infertile) males (Buhler, 1985;Slim et al, 1994). However, there are anecdotal reports of individuals with i(Yp) who have had phenotypic abnormalities such as short stature, 'Tumer-like' features, and, rarely, microcephaly and mental retardation (Page, 1987;Page, personal communication).…”

Sex chromosome markers: Characterization using fluorescence in situ hybridization and review of the literature

“…Including the present 23 cases, a total of 86 sex chromosome markers studied with FISH have been reported Crolla and Learna, 1988;Kozma et al, 1988;Crolla et al, 1989;Babu et al, 1990;Cole et al, 1990;Guttenbach et al, 1990;Koch et al, 1990;Lin et al, 1990;Cooper et al, 1991;Pohlschmidt et al, 1991;Bajalica et al, 1992;Bernstein et al, 1992;Hou et al, 1992;Lindgren et al, 1992;Qu et al, 1992;Tharapel et al, 1992;Van Dyke et al, 1992;Dennis et al, 1993;Duncan et al, 1993;Pezzolo et al, 1993;Rajangam et al, 1993;Zenger-Hain et al, 1993; Cole et al, 1994;Daniel et al, 1994;Macera et al, 1994;Robson et al, 1994;Slim et al, 1994;Amiel et al, 1995;Callén et al, 1995;Cantú et al, 1995;Gonzalesdel Angel et al, 1995;Silahtaroglu et al, 1995]. These cases can be subdivided into four ascertainment groups: 1) Ullrich-Turner syndrome without mental retardation, 2) Ullrich-Turner syndrome with mental retardation, 3) prenatally diagnosed cases, and 4) other cases.…”

“…Eight of the twelve patients (67%) were found to have a Y-derived marker (Table V) [one mar(Y), one ring (Y), three iso(Yp), two dic(Yp), and one complex derivative Y chromosome] and were reported to be normal males (six livebirths and two therapeutic abortus). One of these males was reported to have hypospadias and seminiferous tubules without germinal cells [Slim et al, 1994]. Four patients (33%) were found to have an X-derived marker.…”

Cytogenetic and Molecular Characterization of Y Isochromosome in a 63XO/64Xi(Yq) Mosaic Karyotype of an Intersex Horse

“…For example, the location of cattle SRY on the long arm of the Y chromosome explains why animals with i(Yp) are phenotypically females [Pinheiro et al, 1990;Kawakura et al, 1997]. Furthermore, many different Y isochromosome-associated phenotypes have been reported for humans, depending on whether the aberration involves the p-or the q-arms [de la Chapelle, 1982;Slim et al, 1994]. Because human SRY is located next to the PAR in Yp [Skaletsky et al, 2003], the loss of the short arm accompanied with the formation of i(Yq) is associated with failed testicular induction, resulting in female phenotype, unless there are XY cell lines to compensate this loss [Haaf and Schmid, 1990;Codina-Pascual et al, 2004].…”