[Delayed onset holocarboxylase synthetase deficiency with normal pyruvate carboxylase activity].

We report a case of holocarboxylase synthetase deficiency with normal pyruvate carboxylase activity in the lymphocytes of an 8 year-old girl with clinical toxicity without the classic dermatological involvement. The identification of three nucleotide changes in the holocarboxylase synthetase (HLCS) gene, only one of them described as a pathogenic mutation could be related to a slight variant of the disease that would explain the unusual presentation beyond the age of infant. Treatment with biotin at 40 mg/day with protein controlled diet allows normal physical growth and psychomotor development for their age.