Division of Genetics and Metabolism

Test module: Biotinidase Deficiency

Estimated time to complete:6 min.
Number of questions: 6

Your name:

1.  Profound and partial biotinidase enzymatic activity are defined as

Profound <10%, Partial 10-50%
Profound <5%, Partial 5-30%
Profound <10%, Partial 10-30%
Profound <5%, Partial 5-50%

Note: You must check your answer after each selection.

2. The combined incidence of partial and profound biotinidase deficiency among newborns is


3. If 2 people, each with a single mutation causing 50% biotinidase deficiency, have a child, what are the chances of being affected with either partial or profound biotinidase deficiency?

If the child is male, his chances are 50%
If the child is female, her chances are 0%
Regardless of sex, the child’s chances are 75%
Regardless of sex, the child’s chances are 25%

4. After a positive newborn screen for biotinidase deficiency, what is the gold standard for confirmatory testing?

Quantitative determination of blood biotinidase enzyme activity
DNA testing to identify the mutation
Repeating a second newborn screen
Comparative genomic hybridization

5. A D444H mutation on each allele would yield what percent of total enzymatic activity?


6. Treatment of profound biotinidase deficiency in the newborn period is

not necessary until after 6-12 months of age
needed with high dosages of vitamin B12 and biotin
effective with 10 milligrams/day of biotin
helpful but does not prevent symptoms

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