ABCA12 and autosomal recessive congenital ichthyosis: For instance, while biallelic null-variants in ABCA12 cause the very severe harlequin type of ARCI, ‘milder’ variants, usually missense or splice-site variants, cause a type of ARCI with or without a collodion membrane and erythroderma that is very similar to other forms of ARCI that do not affect life expectancy in most cases [10].