Ichthyosis follicularis, alopecia and photophobia (IFAP) is a rare 
genodermatosis. Most patients have been men without significant family history. 
We present the largest kindred of IFAP reported to date in the medical 
literature clearly demonstrating X-linked inheritance. The gene defect has 
recently been mapped to Xp22.11-p22.13. Missense mutations of the gene, MBTPS2, 
which codes for an intramembrane zinc metalloprotease essential for cholesterol 
homeostasis and endoplasmic reticulum stress response, are associated with the 
IFAP phenotype in this kindred. We describe the clinical features and discuss 
the differential diagnosis of IFAP. Our proband has benefited from treatment 
with acitretin.