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Neuropediatrics 2022; 53(03): 200-203
DOI: 10.1055/s-0041-1736181
Short Communication

Genotype-Phenotype Dissociation in Two Taiwanese Children with Molybdenum Cofactor Deficiency Caused by MOCS2 Mutation

Hsiu-Fen Lee
1   College of Medicine, National Chung Hsing University, Taichung, Taiwan
2   Division of Pediatric Neurology, Children's Medical Center, Taichung Veterans General Hospital, Taichung, Taiwan
,
Chia-Chi Hsu
4   Division of Pediatric Genetics and Metabolism, Children's Medical Center, Taichung Veterans General Hospital, Taichung, Taiwan
,
Ching-Shiang Chi
3   Division of Pediatric Neurology, Department of Pediatrics, Tungs' Taichung MetroHarbor Hospital, Taichung, Taiwan
5   College of Life Sciences, National Chung Hsing University, Taichung, Taiwan
,
Chi-Ren Tsai
2   Division of Pediatric Neurology, Children's Medical Center, Taichung Veterans General Hospital, Taichung, Taiwan
› Author Affiliations Funding The authors received no financial support for the research, authorship, and/or publication of this article.
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Abstract

Background To describe the genotype-phenotype dissociation in two Taiwanese patients with molybdenum cofactor deficiency (MoCoD) caused by MOCS2 gene mutations.

Patient Description Patient 1 exhibited early-onset neurological symptoms soon after birth, followed by subsequent myoclonic seizures and movement disorder. The brain magnetic resonance imaging (MRI) showed diffuse brain injury with cystic encephalomalacia along with bilateral globus pallidi involvement, hypoplasia of corpus callosum, and cerebellar atrophy. Patient 2 had a mild phenotype with prominent movement disorder after intercurrent illness, and the brain MRI showed selective injury of the bilateral globus pallidi and the cerebellum. Both patients had markedly low levels of plasma uric acid and harbored the same MOCS2 homozygous c.16C > T mutation. Patient 1 showed chronic regression of developmental milestones and died of respiratory failure at the age of 8 years, whereas patient 2 demonstrated improvement in motor function.

Conclusion Genotype-phenotype dissociation could be noted in patients with MoCoD due to MOCS2 mutation. Patients with neonatal seizures, developmental delay, movement disorder, and motor regression after an illness, as well as focal or bilateral involvement of the globus pallidi on the neuroimages, should undergo biochemical testing of plasma uric acid. A pronounced plasma uric acid level is a good indicator of MoCoD. Early diagnosis can allow early provision of adequate genetic counseling.

Keywords

brain MRI - globus pallidus - hypouricemia - MOCS2 gene - molybdenum cofactor deficiency

Ethical Approval

The study was approved by the Ethics Board of Tungs' Taichung MetroHarbor Hospital (TTMHH IRB 105301C) and the Ethics Board of Taichung Veterans General Hospital (TCVGH IRB CE17343A).




Publication History

Received: 30 May 2021

Accepted: 26 August 2021

Article published online:
21 October 2021

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