Holoprosencephaly and Klinefelter Syndrome

oloprosencephaly (HPE) is a malformation that arises during the first 4 weeks of embryonic development (blastogenesis)[1] caused by a failure or incomplete division of the prosencephalon into cerebral hemispheres. This defect is frequently associated with other facial anomalies such as anophthalmia, cyclopia, proboscis, midface clefting, hypertelorism, single maxillary central incisor, and absence of olfactory nerves or corpus callosum. It is a causally heterogeneous field defect caused by: 1) chromosome aberrations in particular trisomy 13[2], partial deletion of the long arm of the chromosome 7, triploidy (69, XXY)[3] and other recessive, dominant, or X-linked genes[2] and multifactorial causes. Klinefelter syndrome is the most common sex chromosome abnormality in men and boys, with a reported prevalence of 0.1% to 0.2% in the general population and of up to 3.1% in the infertile male population[4]. Since the first report in 1942, Klinefelter syndrome has been characterized by small, firm testes and varying symptoms of androgen deficiency including gynecomastia, hypogonadism, infertility[5] and immaturity of external genitalia. Although additional X chromosomes are pre­dominantly inactivated, the entire chromosome region is not inactivated, and inactivated region of the additional X chromosome is likely to be responsible for the clinical features[6].