Results of a nationwide epidemiologic survey of autosomal recessive congenital ichthyosis and ichthyosis syndromes in Japan.

Abstract

Autosomal recessive congenital ichthyosis (ARCI) and ichthyosis syndrome (IS) are rare genetic skin disorders. To estimate the number of patients with ARCI and IS in Japan and clarify the clinicoepidemiologic features of these diseases. We performed a nationwide survey of patients treated for ARCI or IS during January 2005-December 2009. We developed diagnostic criteria and conducted a primary survey in a stratified random sample of Japanese hospitals to quantify the number of outpatients and inpatients with ARCI or IS. We performed a secondary survey of clinicoepidemiologic features in positive cases. The estimated number of patients receiving treatment for ARCI and IS during 2005-2009 was 220 (95% confidence interval [CI] 180-260). The estimated disease distribution was as follows: 95 (95% CI 80-110) patients with nonbullous congenital ichthyosiform erythroderma, 30 (95% CI 20-40) with lamellar ichthyosis, 15 (95% CI 10-20) with harlequin ichthyosis, and 85 (95% CI 50-120) with IS. Patients with a mild case of the disease might not have visited a dermatology department, potentially causing underestimation of affected patients. We report the estimated number of patients with ARCI and IS in Japan and sex differences in the age distribution.