Trichothiodystrophy with chronic neutropenia and mild mental retardation. Trichothiodystrophy is a feature of several diseases that consist of characteristic hair shaft abnormalities and a wide spectrum of other developmental defects. Detection of sulfur-deficient hairs identifies this disorder and separates it from other similar ectodermal dysplasias with normal sulfur content. Detection of low sulfur hair syndrome is also important for genetic counseling, because the disease appears to be an autosomal recessive trait. We report a patient with chronic neutropenia, mild mental retardation, and low sulfur content in hair. Our case expands the spectrum of disorders associated with trichothiodystrophy. 