Infantile hypertrophic pyloric stenosis: An association in twins?

Abstract

BACKGROUND: The etiology of infantile hypertrophic pyloric stenosis (IHPS) remains a mystery. Some suspected risk factors include birth rank, maternal age, sex, family history and monozygosity in twins. Various theories attempt to explain the etiology of IHPS. Scientific research suggests that enteric neuronal damage and nitric oxide synthase dysfunction may be implicated, but the consensus is that environmental modification must exist to account for the variability in its occurrence. METHOD: Four cases of concordant occurrences of IHPS in twins were examined to determine the history and outcome of IHPS development in twins. Three sets were dizygotic and one was monozygotic. Of the eight infants, three were female, including the one monozygotic pair. In all four cases, a time lag existed between the development of symptomatic onset of IHPS in twin A and twin B. In one set, sonographic confirmation, performed because of IHPS diagnosis in the twin sibling, occurred concurrently with onset of vomiting, leading to early surgery before fluid and electrolyte imbalances developed. CONCLUSIONS: Despite the lack of agreement as to whether the cause of IHPS is genetic, environmental or both, the high concordance rate seen in twins is indisputable. Thus, the empirical evidence provides credence to consider examining the asymptomatic co-twin when one of the twins presents with IHPS.

Familial Aggregation and Heritability of Pyloric Stenosis

“…In some studies, monozygotic twins have been concordant for the disease at a frequency not much higher than that of dizygotic twins, 2,4,5,33 whereas other studies have indicated a higher concordance rate in monozygotic than dizygotic twins. 3,4,10,12,21,35 However, these studies appear too small to be conclusive. In our nationwide study, a child with an affected monozygotic twin (RR = 182) was at 6-fold higher risk of pyloric stenosis than a child with an affected dizygotic twin (RR=29.4).…”

“…8 Among white individuals, pyloric stenosis is relatively common, 2,3,5,[8][9][10] with an incidence of 1.5 to 3 per 1000 live births. 9,10 Other than male sex, 2,3,9-11 the most consistently reported risk factors for pyloric stenosis are a family history of pyloric stenosis [2][3][4]8,10,[12][13][14][15][16][17][18][19][20][21] and being a firstborn child. [2][3][4]11,22 The epidemiological features of skewed sex distribution and clustering of cases within families suggest a genetic component to the etiology.…”

“…Previous studies in twins [3][4][5]12,20,21,[32][33][34] comprise mostly case reports. In some studies, monozygotic twins have been concordant for the disease at a frequency not much higher than that of dizygotic twins, 2,4,5,33 whereas other studies have indicated a higher concordance rate in monozygotic than dizygotic twins.…”

“…In combination with the decrease in incidence in the last decades, 1,2,9,[39][40][41] this suggests that, while carrying the gene(s) increases the propensity for pyloric stenosis development, environmental factors appear to be needed for the disorder to manifest. 10,12,21 Possible postnatal environmental (nongenetic) factors include feeding practice, 42 maternal smoking, 2,41 infant sleeping position, 2,9 and postnatal use of macrolides. 43,44 Along these lines, we speculate whether our finding of a higher absolute risk in twins compared with singletons could be explained by differences in exposure to these factors.…”

Trends in the publication of infantile hypertrophic pyloric stenosis in Africa: A systematic review

“…[1] The resulting gastric outlet obstruction produces a clinical manifestation of postprandial, projectile, non-bilious vomiting with associated palpable epigastric abdominal mass. [2][3][4] IHPS is highly prevalent in the Caucasian population with an incidence of 5/1000 newborns [5][6][7] in comparison to the African population in which it is rarer. [8] Other well-documented risk factors include a male preponderance (especially firstborn male) with a 4-5 times higher risk than females, young maternal age, and positive family history of IHPS.…”