A case of 49,XXXXX in which the extra X chromosomes were maternal in origin

Abstract

This report describes an 11 month old female baby with features of pentasomy X. A molecular and cytogenetic evaluation revealed that her karyotype was 49,XXXXX and her extra X chromosomes were of maternal origin. She has muscular hypotonia, mental retardation, a cleft palate, mild hydrocephalus as a result of dilatation of both lateral ventricles, hyperextensible elbow joints, proximal radioulnar synostosis, clinodactyly of the fifth finger, valgus of the feet, and small hands and feet. In addition, she has a persistent pupillary membrane and congenital chorioretinal atrophy. The pathogenesis of pentasomy X is not clear at present, but it is thought to be caused by successive maternal non-dysjunctions.

X Pentasomy in an Intracytoplasmic Sperm Injection Pregnancy Detected by Nuchal Translucency Testing

“…In general, this aneuploid state arises as a result of meiotic malfunction, either maternal or combined maternal and paternal in origin. The most likely mechanism is nondisjunction of maternal X chromosomes in both divisions of meiosis to produce a tetrasome X ovum, and this hypothesis has been supported by molecular analysis of X-linked polymorphic markers [5] . DNA microsatellite analysis in our study showed that the extra X chromosomes were maternal in origin, probably as a result of successive sequential nondisjunctions in meiosis I and II of oogenesis, involving both chromatid pairs in meiosis II.…”

“…Although many studies of numerical and structural chromosome abnormalities in fetuses following ICSI have been published, most of those pregnancies were found to involve sex chromosomes [1,2] , predominantly of paternal origin [2,3,5] . However, maternal-derived autosomal trisomy 18, 21 and monosomy 21 were also reported [2,3] .…”

“…In view of this, many clinicians have recommended karyotyping of both partners prior to planned ICSI [6,7] . X pentasomy is rare, with an estimated frequency of 1/85,000 female live births [5] . To our knowledge, only 31 cases have been previously described.…”

“…The skeleton is usually severely affected with radio-ulnar synostosis, joint laxity and dislocation, and talipes equinovarus. Pubertal development of affected girls is delayed, and fertility is assumed to be reduced [5,8] . Prenatal diagnosis of X pentasomy is generally fortuitous; only 2 cases have been reported.…”

Congenital Radioulnar Synostosis, a case report

“…In 25% of cases, this malformation is genetically conditioned [7]. Congenital radioulnar synostosis is also one of many components of malformation syndromes in children with chromosomal aberrations [8,9]. It is commonly believed that this malformation is connected with chromosome X aberrations [10].…”