Neonatal screening for biotidinidase deficiency: results of a 1-year pilot study in four cities in central Anatolia

Biotin, a water-soluble vitamin, is used as a co-factor by enzymes involved in carboxylation reactions. It functions as the carboxyl carrier for biotin-dependent carboxylases. These enzymes catalyze gluconeogenesis, fatty acid metabolism and amino acid catabolism, thus biotin plays an essential role in maintaining metabolic homeostasis. Biotinidase deficiency is an inherited metabolic disorder characterized by neurological and cutaneous symptoms, treated by oral administration of the vitamin biotin. In central Anatolia marriages between relatives are very common (26%).

We screened 34,378 infants born in four cities in central Anatolia during the one-year period beginning February 2006 for deficiency of the enzyme biotinidase. A simple calorimetric screening procedure was used to detect the presence or absence of biotinidase activity on the same blood-soaked filter paper cards used for screening for phenylketonuria. Positive samples were confirmed with a quantitative method.

One newborn infant with partial biotinidase deficiency (10-30% of mean normal serum activity) was identified during the 12-month pilot study. The estimated incidence of partial biotinidase deficiency in central Anatolia is approximately 1:34,378; this ratio was the same in findings from Istanbul (1:33,307).

Like children with profound biotinidase deficiency, children with partial biotinidase deficiency are symptom-free at birth. However, the subsequent occurrence of symptoms of profound biotinidase deficiency in our patient with partial deficiency suggests that biotin therapy for this condition may be warranted. It is known that in Turkey marriages between relatives are common. If the neonatal screening program is widened the real ratio can be determined, where marriages between relatives are very high in central Anatolia.