Biotinidase deficiency is an autosomal recessive disorder that results from the defective activity of the biotinidase enzyme. Newborns are asymptomatic. If an infant is not screened and/or left untreated, symptoms begin to appear later in infancy and
can include seizures, developmental delay, facial rash, ataxia, and progressive vision and hearing loss. Affected children require life-long treatment with oral biotin and monitoring by both primary care and speciality providers.
Incidence: ~ 1/50,000; affects all ethnic groups
Diagnosis: If biotinidase is low on 2 newborn screens, or absent on the first screen, the diagnosis should be confirmed with biotinidase enzyme activity at a specialized biochemical laboratory. A metabolic geneticist will assist with this testing.
Treatment: If biotinidase deficiency is confirmed, life-long treatment with biotin is indicated and the infant should be followed yearly by a metabolic geneticist.
Raw eggs should be avoided because they contain avidin, an egg-white protein that binds biotin, thus decreasing its bioavailability. (Thoroughly cooked eggs present no problem because heating inactivates avidin, making it incapable of binding biotin.)
False Positives: premature infants, extreme heat and other environmental factors.
*** Result is invalid if the baby has been transfused.