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An X-linked mental retardation syndrome belonging to the group of conditions with the association of intellectual deficit with hypotonic facies. Prevalence is unknown but the syndrome was first described in 1988 in three males (a 3-year-old boy and his two maternal uncles) from a family in which two other males had died in infancy/childhood. All affected males had a characteristic facies (bitemporal narrowness, almond-shaped palpebral fissures, depressed nasal bridge, anteverted nares, short and inverted-V-shaped upper lip and macrostomia). The surviving patients also had severe intellectual deficit, short stature, mild obesity, hypogonadism and a low total finger ridge count. The syndrome is caused by missense mutations in the ATRX gene (Xq13.3). Inheritance is X-linked recessive.
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Holmes Gang syndrome is an X-linked mental retardation syndrome that was first described in 1984 in three males from two generations of the same family. The syndrome has characteristics of microcephaly, a large anterior fontanelle, characteristic facies (short nose, anteverted nares, epicanthal folds), club-foot deformity and delayed psychomotor development. One of the affected males also had renal hypoplasia/dysplasia. All three patients died during infancy. The syndrome is caused by mutations in the ATRX gene (Xq13.3). Inheritance is X-linked recessive.
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