Biotinase deficiency in a child with predominantly spinal cord disease:a case report and literature review / 中华神经科杂志

ABSTRACT

Objective:To describe the clinical features of pediatric biotinase deficiency (BTD) manifested as spinal cord disease.Methods:The clinical data of a child with spinal cord lesions due to biotinase deficiency, diagnosed in Beijing Children′s Hospital in 2020, were collected. The cases with complete clinical data retrieved on literature reported in China National Knowledge Infrastructure, Wanfang Data knowledge Service Platform and PubMed (up to August 2021) by using search terms of biotinase deficiency, pediatric, spinal cord, myelopathy and myelitis were summarized.Results:The patient was a 3 years and 5 months old boy with the main clinical manifestations of subacute progressive limb weakness and wheezing. Physical examination showed sparse hair, rough skin, spastic paraparesis and developmental delay. Cerebrospinal lactic acid was increased (5.67 mmol/L). Cranial magnetic resonance imaging (MRI) showed diffuse T 2/fluid attenuated inversion recovery hyperintensity of the midbrain, dorsal pons, edulla, periacqueductal grey and optic tracts. Spinal cord lesions were extended from the medulla up to the level of the conus. Urineketone bodies and 3-hydroxyisurate were increased. The activity of biotinidase was 0.27 pmol/min (3 mm disc), being 7% of mean normal serum activity. Genetic studies revealed homozygous mutation in the BTD gene [c.284T>A (p.I95N)]. After biotin supplementation for 6 months, the only evident abnormality was residual spasticity of lower limbs. Fourteen English literatures and 2 Chinese literatures including 18 cases were collected. The onset age was from 2 months to 15 years (median age was 4 years). Among them, 11 cases had cranial MRI abnormalities, of which all involved brain stem, 6 cases involved optic tracts and (or) optic chiasm. All 18 cases had spinal cord MRI abnormalities with longitudinally extensive lesion, mostly involved cervical and thoracic spinal segments, and 3 cases involved all spinal segments. Twelve cases received immunotherapy, and 6 were partially improved, 6 were completely invalid. After biotin supplementation, 12 patients had neurological disability. Conclusions:BTD should be included in the differential diagnosis of subacute myelopathy, regardless of the onset age. Early diagnosis and treatment can prevent irreversible neurological damage.