Fragile X Syndrome Phenotype Sample Clauses

Fragile X Syndrome Phenotype. Intellectual disability is the hallmark feature of fragile X syndrome. The level of impairment ranges from mild to severe, with IQ scores of affected males typically between 25 and 70. Arithmetic, spatial memory, abstract thought, and complex reasoning are particular areas of weakness (Xxxxxx et al. 1988), while verbal skills, including vocabulary and reading, are less significantly impaired (Xxxxxxxx et al. 1985). This is particularly true of receptive verbal skills, which are less impaired than expressive verbal skills (Xxxxxxx et al. 2001). Additionally, fragile X males tend to perform better at fact learning and school-related skills than at processing novel information (Xxxxxx et al. 1988). Furthermore, longitudinal studies suggest that the IQ of affected males declines over time, beyond their initial levels of impairment. The pattern of this decline is not consistent with a degenerative process, but rather a slowing of the intellectual growth of the fragile X male when compared to his unaffected peers and relatives (Xxxxxxx et al. 2005; Hall et al. 2008). There are three subtle physical findings which eluded Xxxxxx and Xxxx in their 1943 pedigree but are now known to be common in fragile X syndrome. The first of these is the typical facial appearance of fragile X patients. Although not grossly dysmorphic, certain common features are shared: a long, narrow face, prominent jaw, large forehead, and large everted ears (Xxxxxx et al. 1980). A subset of these facial features can be seen in over 90% of affected males, but less than half of affected females (Xxxxxxxx et al. 1994). Among the specific features, large ears are the most closely associated with fragile X as compared to other causes of intellectual disability (Xxxxxx et al. 2009). Macroorchidism, the second noteworthy physical feature, is present in nearly all postpubertal fragile X males (Xxxxxxxx et al. 1994; Xxxxxx et al. 2009). After multiple families were described with both X-linked ID and macroorchidism (Xxxxxx et al. 1975; Xxxxx et al. 1976; Xxxxxxxxx et al. 1977; Xxxxx et al. 1978), fragile X families were re- evaluated for the presence of enlarged testes, and macroorchidism was indeed found to be associated with fragile X syndrome (Xxxxxx et al. 1980). While a mouse model of fragile X showed increased Sertoli cell proliferation to be the cause of murine macroorchidism (Slegtenhorst-Eegdeman et al. 1998), no human studies have corroborated this finding; thus, the cause of macroorchidism i...