Familial translocation t(Y;15)(q12;p11) and de novo deletion of the Prader-Willi syndrome (PWS) critical region on 15q11-q13

Abstract

We describe a 17-year-old girl with mild Prader-Willi syndrome (PWS) due to 15q11-q13 deletion. The deletion occurred on a paternal chromosome 15 already involved in a translocation, t(Y;15)(q12;p11), the latter being present in five other, phenotypically normal individuals in three generations. This appears to be the first case of PWS in which the causative 15q11-q13 deletion occurred on a chromosome involved in a familial translocation, but with breakpoints considerably distal to those of the familial rearrangement. The translocation could predispose to additional rearrangements occurring during meiosis and/or mitosis or, alternatively, the association of two cytogenetic anomalies on the same chromosome could be fortuitous.

Recurrent trisomy 15 in a female carrier of der(15)t(Y;15)(q12;p13)

“…Although the t(Y;15)(q12;p11) is not known to be associated with PWS or AS, one report describes a child with PWS and a paternally derived der (15)t(Y;15)(q12;p11) [Eliez et al, 1997]. In this patient a de novo deletion of the PW syndrome critical region was found on the derivative chromosome 15 and it was proposed that the t(Y;15) may have predisposed to the generation of a microdeletion within the PWS region.…”

A normal birth following preimplantation genetic diagnosis by FISH determination in the carriers of der(15)t(Y;15)(Yq12;15p11) translocations: two case reports

“…The deletion occurred on a paternally derived der (15)t(Y;15) (q12;p11). Alternatively, the association may have been fortuitous too [11]. It remains to be proven and further investigated.…”

Prenatal diagnosis of the maternal derivative chromosome der(15)t(Y;15)(q12;p13) in a dizygotic twin pregnancy

“…Some patients with PWS exhibit translocations involving chromosome 15 with deletion of the PWS region. Although the t(Y;15)(q12;p13) translocation was not involved in the PWS critical region (15q11–q13), two rare reports indicated that familial t(Y;15)(q12;p13) may result in predisposition to the generation of microdeletions within the PWS region or trisomy 15 [1011 ]. These studies suggested the possibility of an increased risk for abnormal offspring.…”