A novel stop-gain mutation in DPYS gene causing Dihidropyrimidinase deficiency, a case report

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.

Dihydropyrimidinase deficiency with atrioventricular septal defect: a case report

OBJECTIVES

Dihydropyrimidinase deficiency is a rare autosomal recessive disorder of the pyrimidine degradation pathway, with fewer than 40 patients published. Clinical findings are variable and some patients may remain asymptomatic. Global developmental delay and increased susceptibility to 5-fluorouracil are commonly reported. Here we present atrioventricular septal defect as a novel feature in dihydropyrimidinase deficiency.

CASE PRESENTATION

A four-year-old male with global developmental delay, dysmorphic facies, autistic features and a history of seizures was diagnosed with dihydropyrimidinase deficiency based on strikingly elevated urinary dihydrouracil and dihydrothymine and a homozygous pathogenic nonsense variant in DPYS gene. He had a history of complete atrioventricular septal defect corrected surgically in infancy.

CONCLUSIONS

This is the second report of congenital heart disease in dihydropyrimidinase deficiency, following a single patient with a ventricular septal defect. The rarity of the disease and the variability of the reported findings make it difficult to describe a disease-specific clinical phenotype. The mechanism of neurological and other systemic findings is unclear. Dihydropyrimidinase deficiency should be considered in patients with microcephaly, developmental delay, epilepsy and autistic traits. We suggest that congenital heart disease may also be a rare phenotypic feature.

The diagnostic odyssey of a patient with dihydropyrimidinase deficiency: a case report and review of the literature

Dihydropyrimidinase (DHP) deficiency is an autosomal recessive metabolic disorder caused by biallelic pathogenic variants of DPYS Patients with DHP deficiency exhibit a broad spectrum of phenotypes, ranging from severe neurological and gastrointestinal involvement to cases with no apparent symptoms. The biochemical diagnosis of DHP deficiency is based on the detection of a significant amount of dihydropyrimidines in urine, plasma, and cerebrospinal fluid samples. Molecular genetic testing, specifically the identification of biallelic pathogenic variants in DPYS, has proven instrumental in confirming the diagnosis and facilitating family studies. This case study documents the diagnostic journey of an 18-yr-old patient with DHP deficiency, highlighting features at the severe end of the clinical spectrum. Notably, our patient exhibited previously unreported skeletal features that positively responded to bisphosphonate treatment, contributing valuable insights to the clinical characterization of DHP deficiency. Additionally, a novel DPYS variant was identified and confirmed pathogenicity through metabolic testing, further expanding the variant spectrum of the gene. Our case emphasizes the importance of a comprehensive diagnostic approach using genetic sequencing and metabolic testing for accurate diagnosis.