HLCS and hyperinsulinemic hypoglycemia, familial, 4: The three autosomal recessive syndromes, referred to as “multiple carboxylase deficiency,” holocarboxylase synthetase deficiency (the “neonatal form”), biotinidase deficiency (the “juvenile form”), and the rare syndrome of inability to transport biotin into cells, all have similar clinical features and can cause biotin deficiency [1].