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Pyrimidine Metabolism Disorders as Rare Cause of Psycho-motor Retardation, Dysmorphism and Epilepsy

OBJECTİVES We describe 2 patients with psycho-motor developmental delay, dysmorphic feautures and epilepsy diagnosed with pyrimidine metabolism disorder by detecting mutations in UPB1 and DPYS with whole exome sequencing (WES) analysis.

METHODS The data of the cases were obtained retrospectively from the pediatric neurology records of Kocaeli University Faculty of Medicine.

RESULTS

Five-moth-old boy presented with severe psycho-motor retardation, dysmorphism and epileptic spasms. EEG examination revealed hypsarrhytmia. The patient was diagnosed as West syndrome. Now, he is 2-year-old, and still has severe psycho-motor retardation, partially controlled seizures with polytherapy. Routine diagnostic tests were uninformative. WES analysis showed pathogenic, compund heterozygous variants in UPB1, for each variant parents were heterozygous. 16-month-old boy presented with mild psycho-motor retardation, dysmorphism and seizures. The etiology could not be identified with routine diagnostic tests. Now, he is 14-year-old, needs special education support, and seizures are partially controlled with monotherapy. WES analysis showed a likely-pathogenic, homozygous variant of DPYS. Both patients are diagnosed with pyrimidine metabolism disorder. The diagnosis was confirmed by urine pyrimidine metabolite analysis.

CONCLUSION Psycho-motor retardation, dysmorphism and seizures are frequently observed in patients with inborn errors of metabolism disorders. Urine pyrimidine metabolites should be screened in patients with negative metabolic disorders screening before performing more complicated diagnostic tests.
Keywords: pyrimidine, metabolic disorders, epilepsy, urine metabolite