ATR-X syndrome

The X-linked recessive ATR-X syndrome is characterized by hypotonia, facial dysmorphism, genital malformation and severe mental retardation. It only affects male patients. Heterozygous women remain symptom free. The persons affected usually have a very limited ability to speak. One part suffers from seizures.

Characteristic features of the syndrome are the typical facial features, a conspicuous mouth, hypotonia, failure to thrive and the genital anomalies. Examples are descended testes and intersexual genitals. Most sufferers suffer from dwarfism, microcephaly, and gastrointestinal problems. Less common are heart defects, deafness, ocular involvement, epilepsy, and mild microcytic anemia.

Mutations in the ATRX gene encoding the ATRX protein are the cause of the syndrome. The mutations result in changes in the methylation pattern of the DNA in heterochromatic regions.