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Table 2 Biochemical and molecular profile of patients with reduced biotinidase activity (n = 38)

From: Biotinidase deficiency: clinical and genetic studies of 38 Brazilian patients

Patient

Gender

Allele 1

Allele 2

Expected type of BD according to genotype

Type of BD according to enzyme activityb

Biotinidase activitya

Manner of diagnosis

01

F

c.643C > T (p.L215F)

c.755A > G (p.D252G)

Profound

N/A

21.88 U

NS

02c

M

c.755A > G (p.D252G)

c.755A > G (p.D252G)

Profound

Profound

0.1; 0.4; 0.33; 0.44; 0.16; 0.32

S

03

F

c.1612C > T (p.R538C)

c.1612C > T (p.R538C)

Profound

Profound

0.12

S

04

M

c.1330G > C (p.D444H)

c.98_104del7ins3

Partial

Partial

1.5

NS

05

F

c.1330G > C (p.D444H)

c.[470G > A;1330G > C] (p.[R157H;D444H])

Partial

Partial

1.8

NS

06

M

c.1330G > C (p.D444H)

c.[511G > A;1330G > C] (p.[A171T;D444H])

Partial

Partial

1.4

NS

07

F

c.1330G > C (p.D444H)

c.[511G > A;1330G > C] (p.[A171T;D444H])

Partial

Hz

2.5

NS

08

F

c.1330G > C (p.D444H)

c.[511G > A;1330G > C] (p.[A171T;D444H])

Partial

N/A

45.81 U

NS

09

F

c.1330G > C (p.D444H)

c.594_596delCGT (p.V199del)

Partial

Partial

1.2; 1.9

NS

10

F

c.1330G > C (p.D444H)

c.[595G > A;1413 T > C] (p.[V199M;C471C])

Partial

Hz

2.8

NS

11

M

c.1330G > C (p.D444H)

c.755A > G (p.D252G)

Partial

Partial

1.7

NS

12

F

c.1330G > C (p.D444H)

c.755A > G (p.D252G)

Partial

Partial

1.2

NS

13

F

c.1330G > C (p.D444H)

c.755A > G (p.D252G)

Partial

Hz

2.4

NS

14

M

c.1330G > C (p.D444H)

c.755A > G (p.D252G)

Partial

N/A

51.37 U

NS

15

M

c.1330G > C (p.D444H)

c.933delT

Partial

Partial

1.6

NS

16

F

c.1330G > C (p.D444H)d

c.100G > Ad

Partial or Hz

Partial

1.2; 2.04

NS

17

M

c.1330G > C (p.D444H)d

c.643C > T (p.L215F)d

Partial or Hz

Hz

2.4

NS

18

F

c.1330G > C (p.D444H)d

c.1629C > A (p.D543E)d

Partial or Hz

Hz

2.6

NS

19

M

c.1413 T > C (p.C471C)

c.[511G > A;1330G > C] (p.[A171T;D444H])

Hz

Hz

3.3

NS

20

M

c.1595C > T (p.T532M)

N

Hz

Hz

1.5; 2.9; 4.4

NS

21

M

c.1330G > C (p.D444H)

c.1330G > C (p.D444H)

Hz

Hz

0.7; 3.3

NS

22

M

c.1330G > C (p.D444H)

c.1330G > C (p.D444H)

Hz

Hz

3.7

NS

23

M

c.1330G > C (p.D444H)

c.1330G > C (p.D444H)

Hz

Hz

2.8; 2.7

NS

24

M

c.1330G > C (p.D444H)

c.1330G > C (p.D444H)

Hz

N/A

48.75 U

NS

25

M

c.1330G > C (p.D444H)

c.1330G > C (p.D444H)

Hz

N/A

51.83 U

NS

26

M

c.1330G > C (p.D444H)

c.1330G > C (p.D444H)

Hz

N/A

46.88 U

NS

27c

M

c.1330G > C (p.D444H)

c.1330G > C (p.D444H)

Hz

N/A

52.73 U

NS

28

F

c.1330G > C (p.D444H)

c.1330G > C (p.D444H)

Hz

N/A

40.94 U

NS

29

F

c.1330G > C (p.D444H)

c.1330G > C (p.D444H)

Hz

N/A

45.37 U

NS

30

M

c.1330G > C(p.D444H)

N

N

Borderline (Hz/N)

4.9

NS

31

F

c.1330G > C (p.D444H)

N

N

Hz

3.1

NS

32

F

c.1330G > C (p.D444H)

N

N

Hz

3.8; 2.7

S

33

M

c.1413 T > C (p.C471C)

N

N

Borderline (Hz/N)

0.1; 2.6; 4.9

NS

34

F

N

N

N

Hz

4.1

S

35

M

N

N

N

Hz

3.7

S

36

F

c.1330G > C (p.D444H)

c.119 T > C (p.L40P)

Unknown

Partial

1.7

NS

37

M

c.1330G > C (p.D444H)

c.479G > A (p.C160Y)

Unknown

Borderline (Partial/Hz)

0.2; 1.7; 2.2

NS

38

M

c.664G > A (p.D222N)

N

Unknown

Hz

3.5

NS

  1. aThe cutoff for filter-paper tests performed at laboratory A is 70U. For quantitative testing in serum or plasma performed at laboratories B, C, D, the measurement unit is nmol/min/mL and the reference range is 5.0-10. Unless otherwise specified, the unit of enzyme activity is nmol/min/mL.
  2. bThe following enzyme activity ranges were used for phenotypic classification: <0.75, profound deficiency; 0.75-2.25, partial deficiency; 2.26-5.0, heterozygosity. If more than one measurement was obtained, the highest value was considered. Values within ± 0.1 of a cutoff point were classified as borderline.
  3. cPatients with consanguineous parents.
  4. dWhether it is in cis or trans configuration with the other variant found remains undetermined.
  5. Novel variants shown in bold type, and synonymous variants, in italics.
  6. BD, biotinidase deficiency; F, female; M, male; NS, neonatal screening; S, symptoms; Hz, heterozygosity; N/A, not available; N, normal.