The association of molybdenum cofactor deficiency and pyloric stenosis

Coexistence of molybdenum cofactor deficiency type A and hypertrophic pyloric stenosis, a new case

Molybdenum cofactor deficiency is a rare neurometabolic disease that is usually characterized by seizures, abnormal muscle tonus, developmental delay and poor nutrition, and is seen soon after birth. Pyloric stenosis causes serious vomiting in the first months of life. The presence of neurologic damage in molybdenum cofactor deficiency and possible abnormal innervations may cause pyloric stenosis; however, the pathogenesis is unclear. Pyloric stenosis with molybdenum cofactor deficiency has been described in two cases. Herein, we report the third case and suggest that hypertrophic pyloric stenosis should be kept in mind as a clinical manifestation of molybdenum cofactor deficiency.

Infantile Hypertrophic Pyloric Stenosis: An Epidemiological Review

Infantile hypertrophic pyloric stenosis (IHPS) is the most common gastrointestinal disease among infants. IHPS occurs as an isolated condition or together with other congenital anomalies. Association with genetic and environmental factors, bottle feeding, younger maternal age, maternal smoking, and erythromycin administration in the first two weeks of life has been shown. Familial aggregation has been described and a family history is seen in 47.9 percent of siblings. Infants typically present with projectile vomiting associated with symptoms of failure to thrive. An olive-like mass palpable in the right upper abdominal quadrant is being reported less frequently because of earlier diagnosis by ultrasound. IHPS is generally corrected through laparoscopic pyloromyotomy. Endoscopic pyloric balloon dilation is a novel alternative. Further studies on different populations, the general population, and familial segregation to determine the prevalence, influence, and mode of familial aggregation and correlation with environmental factors are needed to determine the etiology of IHPS.

Critical appraisal of genotype assessment in molybdenum cofactor deficiency

INTRODUCTION

Molybdenum cofactor deficiency (MoCD) is an ultra-orphan, life-threatening disease. Substrate substitution therapy has successfully been performed in single cases of MoCD type A and clinical trials are underway for drug registration. We present an innovative approach for classification of genotype severity to test the hypothesis that milder sequence variants in MoCD result in a less severe disease phenotype quantitated by patient survival.

METHODS

All available worldwide published cases with clinical and genetic data were included (n = 40). We stratified the already published disease causing sequence variants as mild or severe with the use of in silico prediction programs, where possible and assessed the possible impact of the variants on the expression of the gene or function of the expressed protein. In a compound heterozygous situation the mildest sequence variant determined the genotype. Subsequently, clinical manifestations and outcomes of both groups were compared.

RESULTS

Patients with a severe genotype showed a median survival of 15 months and had a lower probability of survival compared to patients with mild genotypes who were all alive at last reported follow-up (p = 0.0203, Log-rank test).

DISCUSSION

The severity of the genotype assessed by in silico prediction and further classification explained survival in molybdenum cofactor deficiency and may therefore be considered a confounder for the outcome of therapeutic clinical trials requiring adjustment in the clinical trial design or analysis. These results should further be investigated by future in vitro or in vivo functional studies. Caution should be taken with this approach for the classification of variants in molecular genetic diagnostics or genetic counseling.