Sex chromosome aneuploidy and anthropometry

Abstract

Human growth is a highly complicated process influenced by genetic, hormonal, environmental, dietary, metabolic and socioeconomic factors. Although the interaction between sex steroids and the growth hormone (GH)-IGF-axis is of major importance in regulating growth, multiple genetic factors, including genes located on the sex chromosomes play independent roles. Sex chromosome aneuploidy is the most common chromosome disorder in humans, with an incidence of 1 in 400 newborns. The most frequent type of aneuploidy involve the addition or deletion of an X or Y chromosome resulting in a 47,XXX, 45,X, 47,XXY or 47,XYY karyotype. The clinical and behavioural characteristics of these conditions are relatively well described in the literature, whereas, the addition of more than one extra sex chromosome is rare and relevant clinical information is limited. Sex chromosome aneuploidies have a high but varying impact on normal growth, and disorders of growth may be the first or only symptom of an underlying genetic disorder. Interestingly, the presence of supernumerary sex chromosomes affects growth in a dimorphic pattern indicating that genes on the X and the Y chromosome affect height in a different manner.