[Trichothiodystrophy: progresssive manifestations].

INTRODUCTION

Trichothiodystrophy is an autosomal recessive genodermatosis associating congenital dysplasia of the hair and neuroectodermal defects. Clinical expression is variable, although abnormalities are generally noted from birth. We report trichothiodystrophy in two brothers with the same phenotype who presented unusual progressive manifestations.

OBSERVATIONS

Case 1: A six-year-old boy was seen for vesicular blisters due to photosensitization. Clinical examination showed dry, brittle, unmanageable hair, discrete koilonychia-type nail defects and an ichthyosiform state. The teeth were normal. In addition to psychomotor retardation, the patient presented a dysmorphic syndrome (poorly rimmed low-set ears; thick, triangular upper lip; scaphocephalic skull; short hands) and congenital bilateral cataract. The diagnosis of trichothiodystrophy was confirmed by a study of DNA repair after exposure to ultraviolet light. A repair defect was found similar to that in xeroderma pigmentosum group D. The patient experienced a worsening of psychomotor retardation and episodes of hair loss with edema and inflammation of the scalp resulting from infections. He also showed marked asthenia which resolved spontaneously within a few months. Case 2: The other brother, born as a collodion baby, presented the same clinical picture (cutaneous, exoskeletal, dysmorphic), including congenital bilateral cataract, photosensitivity and a parenchymatous blister-type pulmonary lesion probably secondary to bronchiectasis. The patient's cutaneous state progressively improved. He was seen at six years of age for an episode of inflammatory edema of the scalp with hair loss. Within six months, all of the hair redrew. The diagnosis of trichothiodystrophy was confirmed by a DNA repair defect after exposure to ultraviolet light.

DISCUSSION

Trichothiodystrophy is clinically associated with photosensitivity (P), ichthyosis (I), dry, brittle hair (B), intellectual impairment (I), decreased fertility (D) and short stature (S), which accounts for the acronym PIBIDS or IBIDS syndrome, depending on whether photosensitivity is involved or not (actually in about 50 p. 100 of cases). Other possibly associated features include ungueal dysplasias, bilateral cataract, defective teeth, dysmorphic disorders predominant in the ears, neurologic disorders, pulmonary bronchiectasis and recurrent infections. The two cases presented here were thus very symptomatologically complete. The two problems of current concern are psychomotor retardation and temporary hair loss as a result of infections. The latter has only been described once in the literature. This case was similar to ours since photosensitivity was involved. Analysis of DNA repair also showed a defect after exposure to ultraviolet light similar to that found in xeroderma pigmentosum group D. Thus, episodic hair loss could be a symptom characteristic of forms of trichothiodystrophy with a DNA repair defect. However, the explanation for this hair loss is not known. Other ectodermal dysplasias can be complicated by hair loss with superinfection, such as AEC syndrome (ankyloblepharon, ectodermal dysplasia, cleft palate).