RESUMO
Congenital hypertrophic pyloric stenosis is the most common intra-abdominal disease required surgery during the first few months of life. The expression of pyloric stenosis is dependent upon the genetic influence of ancestors affected with the disease, as well as unknown environmental influences in the postnatal period. Pyloric stenosis has been reported in multiple sibs in a family, which suggests the genetic influence on the expression of this disease. Until now, the genetic influence is thought a sex-modified polygenic or multifactorial background which facilitates the expression of a common dominant gene. We experienced a case of congenital hypertrophic pyloric stenosis in a two siblings. The siblings suffered projectile vomiting for 2~4 days at 16 days old of age and 15 days old of age. After we confirmed the diagnosis by upper gastrointestinal series and abdominal sonogram, the Fredet-Ramstedt pyloromyotomy was done successfully. This case suggests the genetic influence on the expression of this disease.