Several cases of IED have been reported as being associated with phenotypic abnormalities (e.g. Dubowitz syndrome or malformation syndromes).40,41 An association between congenital IDI and choanal atresia was recently reported in four children.40 In our experience, we have observed malformations including rectal atresia, choanal atresia or esophageal atresia. We recently reported the association with a non-specific punc-tiform keratitis in more than 50% of patients with clinically and histologically recognized IED.42 Therefore, the diagnostic work-up should include a systematic ophthalmological examination by an experienced specialist. The latter association is intriguing, since punctiform keratitis is also an epithelial disease; thus, studying this condition might help to elucidate the molecular mechanisms of the intestinal epithelial disease. The fact that some children have no ophthalmological symptoms confirms the heterogeneity of the disease.
Interestingly, Lachaux et al have reported a case of a newborn presenting with pyloric atresia and intractable diarrhea.43 Light microscopic examination showed extensive desquamation from fundus to rectum, with only a few epithelial cells remaining at the base of the crypts. Electron microscopy of the gut revealed normal desmosomes, but a cleavage located between the lamina propria and the basal pole of the enterocytes. This first-described disease is supposed to be related to congenital deficiency of a6p4 integrin. This inte-grin is known to be defective in epidermolysis bullosa, in which gross epidermal shedding occurs, although the cutaneous expression of a6p4 integrin appeared normal in this case of IDI. This is consistent with a mutation within an intestinal isoform of the a6p4 integrin, or a deficiency of a related and immunohistochemically cross-reactive intestinal integrin.44,45 Rather like epidermolysis bullosa, which shares several similarities with deficiency of a6p4 integrin at the ultrastructural and possibly molecular level, there are likely to be several distinct mutations that can cause this phenotype.
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