4. Harlequin ichthyosis
Harlequin ichthyosis is an extremely rare genetic mutation that affects the skin. Infants who are born with the condition are covered with a hard and very thick layer of skin, that has deep cracks. Due to this, children experience dehydration and succumb to infections in the first weeks of their lives. The condition results from the mutation of the gene ABCA12 which is essential for making a protein in charge of normal development of skin cells.