Xq chromosome duplication in males: Clinical, cytogenetic and array CGH characterization of a new case and review

Abstract

Males with duplications within the long arm of the X chromosome are rare and most cases are inherited from a maternal heterozygote. We report a male with a de novo Xq duplication and review of the literature. The proband was ascertained prenatally after an abnormal expanded alpha-fetoprotein (AFP) screen and abnormal ultrasound findings. Chromosome analysis on amniocyte and subsequent peripheral blood lymphocyte cultures showed a male karyotype containing additional material on the long arm of the X chromosome. Fluorescence in situ hybridization with an X chromosome whole chromosome paint probe showed that the additional material was derived from the X chromosome, interpreted as a dup(X)(q13.3q24). Further characterization of the duplication by array CGH showed a duplication size between 30-44 Mb as determined by the map position of the flanking clones on the array, and refined the breakpoints of the duplicated region to Xq21.32 --> Xq25. At birth, the proband had multiple craniofacial abnormalities, musculoskeletal anomalies, bilateral cryptorchidism with scrotal hypoplasia, conductive hearing loss, and profound generalized hypotonia despite normal birthweight, length, and head circumference. Although data regarding Xq duplications in males are limited, a clear pattern of characteristic features can be discerned as illustrated in the present case and confirmed in our literature review. Mental, psychomotor and growth retardation, as well as, craniofacial anomalies, muscle hypotonia, hypoplastic genitalia, cryptorchidism, feeding difficulties, and endocrine dysfunction are all significant issues in these individuals.