The main symptoms of late-onset multiple carboxylase deficiency (biotinidase deficiency, McKusick 25326) include ataxia, seizures, hypotonia, psychomotor retardation, alopecia, skin rash, progressive deafness, optic atrophy and lifethreatening episodes of metabolic acidosis. Biochemically, increased lactate and propionate are found in plasma, and, in urine, augmented excretion of lactate, 3-methylcrotonylglycine and 3-hydroxyisovaleric and methylcitric acids. Biotin administration allows the complete remission of clinical and biochemical abnormalities, except for hearing loss and optic atrophy (Sweetman and Nyhan, 1986). EN, a female child, was admitted to the hospital because of acute spastic laryngitis at the age of 32 months. Repeated miscarriages were reported in the maternal family. Before the hospitalization, the patient experienced frequent and prolonged episodes of dyspnoea associated with laryngeal stridor. At the age of one and two years, seborrhoeic dermatitis of the scalp had been followed by sudden alopecia. At admission, the patient was severely ill: dyspnoea, inspiratory stridor, hoarseness and ataxia were present; breath rate was 56/rain. The hairs were sparse, thin and fragile. Laboratory investigations revealed a severe metabolic acidosis compensated by respiratory alkalosis (pH7.4, bicarbonate 6minor/L, pCOz 15.4mmHg, base excess -19, anion gap 28 mmol/L). Despite oxygen administration, humidification and large doses of i.v. bicarbonate, clinical and biochemical abnormalities persisted during the first 48 h of hospitalization. Lactic acidosis (6.3 mmol/L) and hyperalaninaemia (537pmol/L) were then demonstrated. Because of the coexistence of biochemical, neurological and cutaneous abnormalities, biotinidase deficiency was suspected. After obtaining a urine sample, biotin was given perorally (15 mg/day in three doses). We observed the complete normalization of both respiratory symptoms and metabolic abnormalities within two hours of starting the therapy. The urine analysis (before biotin) showed a characteristic organic acid profile: lactate 4.48mmol/mmol creatinine; 3-hydroxypropionate 0.9mmol/mmol creatinine; 3-hydroxyisovalerate 0.61 mmol/mmol creatinine. The diagnosis was confirmed by biotinidase determination, which revealed an absence of activity in the patient's plasma, while, in the father, mother and older sister, the activity was 1.2U/L, 5.03 U/L an d 4.3 U/L, respectively. The patient's psychomotor development, tested by the Brunet-L6zine scale, was 58 at 32 months of age. Brain CT scan and EEG were normal. Our observation, combined with the report of Giardini et al. (1981), where laryngeal stridor was found in patients with pyruvate dehydrogenase deficiency, suggest that the occurrence of laryngeal stridor should lead the clinician
AcknowledgementsThe authors thank Mr M. Azzolina and R. Buehlmann for their technical assistance.