Renal insufficiency is a component of COACH syndrome

Two sisters, ages 23 years and 6 years, respectively, were found to have congenital ataxia, bilateral coloboma, mental retardation and abnormal liver function. Magnetic resonance imaging showed cerebellar vermis hypoplasia in the younger girl and liver biopsy showed hepatic fibrosis in the older sister. This combination of findings suggested a diagnosis of COACH syndrome which is characterized by hypoplasia of cerebellar vermis, oligophrenia, congenital ataxia, coloboma, and hepatic fibrosis. COACH syndrome is a newly recognized condition. So far, five cases have been reported from three sibships. We report two additional cases from one sibship and suggest that several other cases may already exist in literature that were not recognized as having COACH syndrome. The occurrence of multiple cases in single sibships suggests autosomal recessive inheritance. In addition to previously described findings typical of COACH syndrome, the older of our patients showed progressive renal insufficiency with fibrocystic changes on renal biopsy. Renal function has not been described consistently in previous reports of COACH syndrome but has been abnormal in all cases in which it has been investigated. We suggest that renal insufficiency should be considered a common manifestation of COACH syndrome.