Abstract
Molybdenum cofactor deficiency (MoCD) is a rare autosomal recessive metabolic disease
with severe neurological symptoms. Most disease-causing mutations are found in the
MOCS1 gene, corresponding to MoCD type A (MoCD-A). There have been few reports describing
the long-term detailed neurological features with MoCD-A because most patients do
not survive childhood. We describe the clinical, radiologic, biochemical, and genetic
data of two patients (female siblings aged 26 and 22 years) with MoCD-A. Both patients
presented with feeding difficulties, neurological deterioration, and persistent generalized
muscle contraction which can be easily confused with status dystonicus. Biochemical
tests revealed low serum uric acid, elevated urinary sulfocysteine, and xanthine.
Brain magnetic resonance imaging (MRI) revealed distinctive abnormalities in the bilateral
caudate nucleus, putamen, globus pallidus, and cerebral white matter adjacent to the
cortex. The thalamus was relatively unaffected. Genetic testing identified a novel
homozygous variant in the MOCS1 gene (c.949C > T p.Arg317Cys). Biochemical results supported the hypothesis that
this genetic variant is a pathological mutation. When there are symptoms of persistent
generalized muscle contraction and characteristic MRI findings, MoCD should be considered
as a differential diagnosis.
Keywords
molybdenum cofactor deficiency - MOCS1 - status dystonicus - persistent generalized
muscle contraction
