MOLECULAR STUDY BIOTINIDASE DEFICIENCY (BTD GENE) SEQUENCING, WHOLE BLOOD

New Test in CIC Catalog

Test Code: 4155

Sample:	Whole blood - EDTA (5 ml)
Conservation:	Refrigerated
Method:	Sequencing Method
Set Up Days:	Daily
Plazo de Entrega:	47 days
Information:
Biotinidase deficiency is a late-onset form of multiple carboxylase deficiency (see this term), an inborn error of biotin metabolism that, if untreated, is characterized by seizures, breathing difficulties, hypotonia, skin rash, alopecia, hearing loss and delayed development. Prevalence of clinical biotinidase (BTD) deficiency is estimated to be 1/61,000. Carrier frequency in the general population is approximately 1/120. Symptoms of BTD deficiency typically appear within the first few months of life, but later onset has also been reported. BTD deficiency is caused by mutations in the BTD gene (3p25) resulting in reduced or absent BTD activity. This enzyme recycles free, non-protein bound, biotin which is required for multiple biotin-dependent metabolic processes. There are more than 150 known mutations of the BTD gene that cause BTD deficiency. The disorder is detected through newborn screening when available. Other cases are diagnosed by clinical signs and symptoms and confirmed by demonstration of deficient serum BTD activity. Molecular mutation analysis of the BTD gene is also possible. The symptoms of BTD deficiency overlap with those of other metabolic diseases, including holocarboxylase synthetase deficiency (see this term), isolated carboxylase deficiency, nutritional biotin deficiency, zinc deficiency and essential fatty acid deficiency. Prenatal diagnosis for at-risk pregnancies is possible and can be performed by enzymatic analysis or by mutation analysis when the mutation is known. However, because of the treatability of the disorder, prenatal testing is not considered by most families. BTD deficiency is inherited as an autosomal recessive trait. Genetic counseling is recommended for parents of affected children. Parents are obligate asymptomatic heterozygote carriers. Siblings of patients with BTD deficiency should be tested for the deficiency even if they do not exhibit symptoms.
Links:
OMIM Entry - # 253260 - BIOTINIDASE DEFICIENCY
OMIM Entry - 609019 - BIOTINIDASE; BTD

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