Alpha-Thalassemia/Mental Retardation Syndrome, X-Linked (ATRX) is a condition characterized by severe to profound mental retardation, distinctive craniofacial features, hypotonia, genital abnormalities, and hematological features of alpha thalassemia, in the absence of mutations in the alpha-globin gene complex. The distinctive craniofacial features include microcephaly, telecanthus, a short triangular nose with flat nasal bridge and anteverted nostrils, mid face hypoplasia, tented vermilion of the upper lip, and thick or everted vermilion of the lower lip. Genital abnormalities include hypospadias, micropenis, or ambiguous female external genitalia. Most patients have mild to moderate anemia, secondary to alpha-thalassemia. Interestingly, the alpha-thalassemia component is not present in all affected patients.
Diagnosis is based on the clinical features. Most patients tend to show the presence of HbH inclusion bodies in their erythrocytes. However, this is not always the case. Molecular genetic testing for mutations in the ATRX gene is the only confirmatory diagnostic test. Management of the condition involves treating the symptoms. Infants need to be put on calorie dense formula. Excessive drooling can be managed by administration of anticholinergics or botulinum toxin type A injection of the salivary glands, or by surgery. The anemia is mild and does not usually require treatment.