The biotinidase deficiency describes a disorder of biotin (vitamin B7) metabolism, which is based on an activity reduction of the enzyme biotinidase.
Without further treatment, it can lead to respiratory problems, alopecia, loss of blood, skin rashes, seizures and to lead to a deleterious development. Stasis is a recent form of a multiple carboxylase deficiency.
The symptoms usually begin in the first 10 months after birth, although a late onset is not an exclusion criterion for BTD deficiency. It is distinguished in patients with severe deficiency. Less than 10% of the normal activity of serum biotinidase and partial deficiency, which corresponds to 10-30% of mean normal activity.
While untreated individuals with severe deficiencies may have all of the listed symptoms, some patients with partial deficiency may remain symptom-free if untreated and develop symptoms only in stressed situations.
Cause are mutations in the BTD gene at the site 3p25. As a result, BTD activity is reduced or absent altogether. This enzyme is capable of recovering non-protein bound biotin for the many biotin-dependent metabolic processes. To date, more than 150 different mutations have been detected in the BTD gene. Inheritance is autosomal recessive.
If the biotin therapy is started before the onset of first symptoms and is reliably carried out for life, the prognosis is very favorable.