ichthyosis—congenital—autosomal recessive 4A
Definition A form (OMIM: 601277) of autosomal recessive congenital ichthyosis*.
*Congenital ichthyosis is a disorder of keratinisation with abnormal differentiation and desquamation of the epidermis, resulting in abnormal global skin scaling
Synonyms Ichthyosis congenita IIB, ichthyosis—lamellar—type 2, LI2
Main skin phenotypes, ichthyosis
• Lamellar ichthyosis–patients are typically encased in a collodion-like membrane at birth; skin scales develop later and cover the entire surface
• Non-bullous congenital ichthyosiform erythroderma–patients typically are covered by fine whitish scaling on an erythrodermal background; larger brownish scales are seen on the buttocks, neck and legs.
Molecular pathology Defects of ABCA12, which encodes an ATP-binding cassette (ABC) transporter involved in lipid homeostasis, cause:
• Ichthyosis—congenital—autosomal recessive 4A (OMIM:601277) and
• Ichthyosis—congenital—autosomal recessive 4B (OMIM:242500).