Pyloric Stenosis in Danish Children May Be Genetic

Laurie Barclay, MD

June 16, 2010

June 16, 2010 — Pyloric stenosis in Danish children may be genetic, according to the results of a population-based cohort study reported in the June 16 issue of the Journal of the American Medical Association.

"Pyloric stenosis is the most common condition requiring surgery in the first months of life," write Camilla Krogh, MD, from the Statens Serum Institut in Copenhagen, Denmark, and colleagues. "Case reports have suggested familial aggregation, but to what extent this is caused by common environment or inheritance is unknown."

The study goals were to evaluate familial aggregation of pyloric stenosis from monozygotic twins to fourth-generation relatives based on gender and maternal and paternal contributions, and to estimate heritability of this condition.

Of 1,999,738 children who were born in Denmark between 1977 and 2008 and who were followed-up for the first year of life, 3362 had surgery for pyloric stenosis. The primary study endpoint was familial aggregation of pyloric stenosis, as determined by rate ratios.

In the first year of life, the incidence rate of pyloric stenosis was 1.8 per 1000 person-years for singletons and 3.1 for twins. Rate ratios for pyloric stenosis were:

  • 182 for monozygotic twins (95% confidence interval [CI], 70.7 - 467),

  • 29.4 for dizygotic twins (95% CI, 9.45 - 91.5),

  • 18.5 for siblings (95% CI, 13.7 - 25.1),

  • 4.99 for half-siblings (95% CI, 2.59 - 9.65),

  • 3.06 for cousins (95% CI, 2.10 - 4.44),

  • and 1.60 for half-cousins (95% CI, 0.51 - 4.99).

Maternal and paternal relatives of children with pyloric stenosis did not differ in rate ratios. No difference in rate ratios was observed based on gender of the cohort member or the relative. Pyloric stenosis heritability was 87%.

"Pyloric stenosis in Danish children shows strong familial aggregation and heritability," the study authors write.

Limitations of this study include relatively small number of cases, leading to wide, and in some situations overlapping, CIs and lack of data on surgeries before 1977.

"The very high concordance rate among monozygotic twins and the strong aggregation even in more distant relatives argue for an important genetic contribution to its etiology," the study authors conclude. "The similar importance of having affected maternal and paternal half-siblings, together with our observation of a similar risk for dizygotic twins and siblings, indicates that intrauterine environmental factors may have little role in causing pyloric stenosis.... The high rates for twins and siblings should be considered in counseling families with affected children."

The Lundbeck Foundation, the Faculty of Health Sciences, University of Copenhagen, and the Danish Agency for Science, Technology, and Innovation supported this study. The study authors have disclosed no relevant financial relationships.

JAMA. 2010;303:2393-2399.

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