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Table 1 Finding in patients with biotinidase deficiency

From: Genotypic and phenotypic correlations of biotinidase deficiency in the Chinese population

Patient

1

2

3

4

5

6

Diagnosed by

Clinical

Clinical

Clinical

Newborn screen

Newborn screen

Newborn screen

Biotinidase activity (nmol/min/dL) (% of control mean)

12.5 (7.8%)

15.4 (9.8%)

NA

36.5 (23%)

36.3 (23%)

32.5 (20%)

C5OH at newborn screening (μM)

NA

0.17

NA

0.14

0.10

0.12

C5OH at presentation (μM)

3.5

3.37

0.362

–

–

–

BTD mutations

c.460-1G > A/c.1382 T > C (p.V461D)

c.460-1G > A/c.1382 T > C (p.V461D)

c.1384delA (p.R462Gfs) homozygous

c.1250_1251TC > AG (p.V417E)/c.1306G > A (p.E436K)

c.1361A > G (p.Y454C)/c.1306G > A (p.E436K)

c.1250_1251TC > AG (p.V417E)*

Urine GCMS

Elevation of 3-hydroxyisovalerate, 3-methylcrotonylglycine, lactate, pyruvate

Elevation of 3-hydroxyisovaleric acid

Elevation of 3-hydroxyisovaleric acid

NA

NA

No specific finding

Seizure onset age

3 m

3 m

2 m

–

–

–

Respiratory problems

Apnea requiring BiPAP at night

Laryngomalacia

–

–

–

–

Hearing loss

+

–

+

–

–

–

Optic atrophy

+

–

NA

–

–

–

Eczema

+

+

NA

−

−

–

Alopecia

–

–

–

–

–

–

Candidiasis

–

Diaper rash

NA

–

–

–

Current status

10y, developmental delay

3y, normal development

Expired at 2y, developmental delay

5 m, asymptomatic

1 m, asymptomatic

NA

  1. NA: not available, C5OH normal < 0.182 μM, *one allele deletion cannot be excluded