Trichothiodystrophy: sulfur-deficient brittle hair as a marker for a neuroectodermal symptom complex

Area of Science:

• Biochemistry
• Genetics
• Dermatology

Background:

• Trichothiodystrophy (TTD) is a neuroectodermal disorder characterized by sulfur-deficient brittle hair.
• Clinical features include intellectual disability, growth retardation, and ectodermal abnormalities like ichthyosis and nail dystrophy.
• Cystine-deficient hair is a hallmark across all TTD patients.

Observation:

• Microscopic examination of hair from TTD patients revealed striking bright and dark bands under polarizing microscopy.
• These distinctive bands were consistently observed in hair samples with abnormally low sulfur content.
• Previous studies indicated cystine deficiency in TTD hair.

Findings:

• Two-dimensional electrophoresis confirmed reduced synthesis of high-sulfur matrix proteins as the cause of the hair abnormality.
• The observed hair banding directly correlates with decreased sulfur content.
• This molecular defect provides a specific marker for TTD.

Implications:

• The findings suggest a defect in sulfur-containing amino acid metabolism or transport in TTD.
• Understanding the molecular basis of TTD hair abnormalities may aid in diagnosis and management.
• Further research into sulfur metabolism could elucidate the broader neuroectodermal manifestations of TTD.