Table 1.
Biochemical and molecular features of patients detected with biotinidase deficiency
| Sex | BTD activity (nmol/min/ml) | Allele 1 (protein change) | Allele 2 (protein change) | Deficiency classification | |
|---|---|---|---|---|---|
| Child 1 | M | 0.7, 0.7 | c.1455C>G (p.H485Q) | c.1455C>G (p.H485Q) | Profound |
| Mother | F | 3.6, 3.3 | c.1455C>G (p.H485Q) | Wild type | |
| Child 2 | F | 1.4, 1.7 | c.842 C>T (p.A281V)a | c.1330G>C (p.D444H) | Partial |
| Mother | F | 3.4 | c.842 C>T (p.A281V) | Wild type | |
| Father | M | 4.8 | c.1330G>C (p.D444H) | Wild type | |
| Child 3 | F | 1.5, 1.4 | c.1330G>C (p.D444H) | Wild (?) type | Partial |
| Mother | F | 5.4 | c.1330G>C (p.D444H) | Wild type | |
| Father | M | 4.9 | Wild type | Wild (?) type | |
| Child 4 | F | 2.0 | c.529 G>A (p.E177K)b | c.1595C>T (p.T532M) | Partial |
| Mother | F | 3.9 | c.1595C>T (p.T532M) | Wild type | |
| Father | M | 5.1 | c.529 G>A (p.E177K) | Wild type | |
| Child 5 | M | 1.0, 1.2 | c.1629C>A (p.D543E) | c.1629C>A (p.D543E) | Partial |
| Mother | F | 3.1 | c.1629C>A (p.D543E) | Wild type | |
| Father | M | 4.6 | c.1629C>A (p.D543E) | Wild type | |
| Child 6 | F | 1.8 | c.511G>A;1330G>C (p.A171T; p.D444H) | c.1330G>C (p.D444H) | Partial |
| Child 7 | F | 1.8 | c.511G>A;1330G>C (p.A171T; p.D444H) | c.1330G>C (p.D444H) | Partial |
| Child 8 | M | 1.8, 1.8 | c.1489C>T (p.P497S)c | c.1330G>C (p.D444H) | Partial |
Wild (?) = coding and splicing regions of BTD gene corresponded to the wild sequence, but promoter and intronic regions were not completely sequenced
aNewly described mutation predicted to affect protein function (see text)
bNewly described mutation predicted not to affect protein function (see text)
cA silent variant [c.1284C>T (Y428Y)] was also detected together with the pathogenic variant p.P497S, as reported by Wolf et al. (2005)