Possibly the most well-known condition relates to the scaling of the skin in patients with recessive X-linked ichthyosis (RXLI) disorder, characterised by a deficiency of steroid sulfatase (STS) resulting in an excess of CholS at the tissue level that can reach up to 12.5% of total lipids [7,8]. Here, STS is linked to syndromic recessive X-linked ichthyosis.