Recessive X-linked ichthyosis associated with hypertrophic pyloric stenosis: a chance occurrence?

The association of recessive X-linked ichthyosis (RXLI) and hypertrophic pyloric stenosis (HPS) has been considered to be due to a probable contiguous gene defect. However, there are several reports of patients with large deletions on both sides of the steroid sulphatase gene (responsible for RXL1) that show no signs of HPS. We report the third pedigree wherein RXL1 was associated with HPS. Apart from the proband, both diseases showed themselves as independent events in the family tree with ichthyosis present in two other individuals and HPS in three other relatives. We calculated the probability that both diseases occurred simultaneously in the index case as a chance occurrence as 1 : 40 (using the Independence principle of probability). We conclude that in our pedigree it is likely that these two rare diseases show an accidental and not a true genetic association.