Uncombable Hair Syndrome

Uncombable hair syndrome (spun glass hair, pili trianguli et canaliculi) is a hair shaft disorder in which the hair is dry, frizzy, silvery or straw coloured and cannot be combed flat.

It presents in early childhood (3 months to 12 years), in otherwise healthy children, mainly in fair haired Europeans. Girls and boys are equally affected. Inheritance is autosomal recessive (PADI3, TGM3 and TCHH variants) or autosomal dominant with reduced penetrance.

The hair becomes less obvious in adolescence and the condition is benign.

Pathophysiology.

Variants in PADI3, TGM3 or TCHH cause abnormal hair shaft formation, and the shaft is triangular or kidney shaped in cross-section, with a longitudinal groove. Defective cross-linking of the hair shaft proteins gives a rigid hair that stands out.

• Dry, shiny, silvery blond or straw coloured hair that grows in many directions and does not lie flat, with normal strength and length.
• Occasional associations: ectodermal dysplasia, retinal dystrophy, cataract and skeletal anomalies in a few reports.
• Improvement by adolescence in many patients.

• Clinical diagnosis from history and appearance.
• Scanning electron microscopy shows triangular hairs with a longitudinal groove, which is diagnostic. Light microscopy shows some flattened hairs, and polarising microscopy may help.
• Gene testing (PADI3, TGM3, TCHH) when available. Examination of nails, teeth and eyes for associations.

Differential diagnosis.

• Woolly hair syndrome and loose anagen hair.
• Pili torti, monilethrix and trichorrhexis nodosa.
• Frizzy hair from heat and chemical damage.

• Explain the benign nature and the usual improvement with age.
• Gentle hair care: avoid heat, chemical and tight styling. Use a mild conditioner and soft brush.
• Biotin 0.3 mg daily has been used, though evidence of benefit is weak.
• Genetic counselling is offered when the variants are known.

Monitoring. Review as needed.

Referral and escalation. Paediatric dermatology.