Dihydropyrimidinase enzyme deficiency and congenital isolated adrenocorticotrophin deficiency: dual genetic diagnosis in a Sri Lankan boy

We report on a male patient who was investigated for frequent apneic episodes, feeding problems, hypotonia, and left-sided middle cerebral artery infarction in the magnetic resonance imaging at 2 weeks of age. Primary diagnosis of dihydropyrimidinase (DPYS) deficiency was suspected following the analysis of urine for organic acid; DPYS deficiency was strongly suggested by the presence of dihydrouracil, thymine, and uracil. Subsequent genetic evaluation by whole exome sequencing revealed 2 separate mutations, homozygous pathogenic variant c.1010T>C p.Leu337Pro of the DPYS gene, resulting in DPYS deficiency, and homozygous pathogenic variant c.535C>T p.Arg179* of TBX19 gene, which is associated with autosomal recessive congenital isolated adrenocorticotrophic hormone deficiency. Currently, the patient is 2 years old, and he has gross motor retardation and seizure disorder. We suggest that the clinical phenotype of the proband can be a result of mixed expression of both mutations.