Abstract
<jats:title>Abstract</jats:title> <jats:p>This chapter provides pictures and clinical details of Turner XLID, an XLID with microcephaly, hydrocephaly, basal ganglia calcifications, hypotonia, and aggressive adult behavior. The responsible gene is involved in the formation and processing of endocytic vesicles. Turner XLID is caused by an alteration in APIS2 and is allelic to Fried syndrome, Pettigrew syndrome, and IDX59. Microcephaly is noted in early childhood in most and short stature less frequently so. Development is globally delayed, with delay in walking particularly notable. Intelligence is variably impaired, ranging from mild to severe. Problem behavior is particularly notable, especially in adulthood. Typically, affected males are agitated and aggressive, self-abusive, and destructive. Marked hypotonia occurs in childhood, and spasticity occasionally occurs in adulthood.</jats:p>