Screening for biotinidase deficiency in children with unexplained neurologic or developmental abnormalities
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S J Sutherland1, R D Olsen, V Michels
1Department of Medical Genetics, Mayo Clinic and Foundation, Rochester, MN 55905.
Insights
Biotinidase deficiency is rare in children with unexplained developmental delay or neurologic issues. Testing is still important for those with specific symptoms suggesting the condition.
Area of Science:
- Biochemistry
- Genetics
- Pediatric Neurology
Background:
- Biotinidase deficiency is an inherited metabolic disorder affecting biotin metabolism.
- Early diagnosis and treatment are crucial to prevent severe neurologic sequelae.
- The prevalence in children with unexplained neurologic conditions is not well-established.
Purpose of the Study:
- To determine if biotinidase deficiency is more common in children with unexplained developmental delay or neurologic abnormalities compared to the general population.
- To assess the diagnostic yield of biotinidase testing in this specific pediatric cohort.
Main Methods:
- A retrospective study of 274 children (aged 2 weeks to 17 years) with unexplained neurologic abnormalities was conducted over four years.
- Clinical data, including IQ/DQ scores, seizures, hearing loss, motor delay, and muscle tone, were collected.
- Patients were screened for biotinidase activity, excluding those with classical deficiency diagnosed during the study.
Main Results:
- None of the 274 children studied, who presented with non-classic findings, had biotinidase deficiency.
- One patient with a classical presentation was diagnosed but excluded from the study cohort.
- The study found no significant association between biotinidase deficiency and unexplained neurologic abnormalities in the studied group.
Conclusions:
- Biotinidase deficiency does not appear to be a common cause of unexplained developmental delay or neurologic abnormalities in children.
- Routine screening for biotinidase deficiency may not be warranted in all children with non-specific neurologic symptoms.
- Targeted biotinidase testing remains essential for children exhibiting clinical features suggestive of the disorder.
Abstract:
To test the hypothesis that the frequency of biotinidase deficiency is greater in children with unexplained developmental delay or neurologic abnormalities than in the general population, we studied children seen at a large outpatient clinic over a four-year period who had one or more of these neurologic abnormalities and for whom no specific cause for their abnormalities could be found. The group totaled 274 children (163 boys; 111 girls) whose ages ranged from 2 weeks to 17 years. Characteristics were IQ/DQ, 30 to 70 in the 115 for whom scores were available; 41% had seizures; 15% had sensorineural hearing loss; 54% showed gross motor delay or ataxia; and 27% had decreased muscle tone. One patient with a classical clinical picture of biotinidase deficiency was diagnosed during the study period and was not included in the study. None of the patients with nonclassic findings had a deficiency of biotinidase activity. Our results suggest that biotinidase deficiency does not account for a large proportion of children with unexplained neurologic abnormalities or developmental delay. This does not negate the importance of biotinidase testing in children with clinical patterns specifically suggestive of the deficiency.