||Biotinidase deficiency; note ability to treat & variable penetrance
||Carrier of a biotinidase deficiency mutation
||common in clinvar
rs13078881, also known as c.1330G>C, p.Asp444His and D444H, represents a mutation in the BTD gene on chromosome 3.
Inherited recessively, the rs13078881(C) allele is considered by ClinVar (and BabySeq) as a pathogenic mutation for biotinidase deficiency. However, it appears as if the D444H mutation results in 48% of normal enzyme activity, and if found in combination with a BTD gene mutation associated with profound deficiency, may result in partial biotinidase deficiency.[PMID 9654207]
Note that this condition is treatable; children with biotinidase deficiency identified early enough should remain asymptomatic if biotin therapy is instituted early.
[PMID 9375914] Profound biotinidase deficiency in two asymptomatic adults.
[PMID 9654207] Partial biotinidase deficiency is usually due to the D444H mutation in the biotinidase gene.
[PMID 10400129] Mutations causing profound biotinidase deficiency in children ascertained by newborn screening in the United States occur at different frequencies than in symptomatic children.