Sjögren–Larsson syndrome
Sjögren–Larsson syndrome is a rare autosomal recessive form of ichthyosis with neurological symptoms. It can be identified by a triad of medical disorders. The first is ichthyosis, which is a buildup of skin to form a scale-like covering that causes dry skin and other problems. The second identifier is paraplegia which is characterized by leg spasms. The final identifier is intellectual delay. SLS is caused by a mutation in the fatty aldehyde dehydrogenase gene found on chromosome 17. In order for a child to receive SLS both parents must be carriers of the SLS gene . If they are carriers their child has a ¼ chance of getting the disease. In 1957 Sjögren and Larsson proposed that the Swedes with the disease all descended from a common ancestor 600 years ago. Today only 30–40 persons in Sweden have this disease. The usual presentation of crystalline maculopathy is from the age of 1-2 years onwards. Causes. It is associated with a deficiency of the enzyme fatty aldehyde dehydrogenase (ALDH3A2) which is encoded on the short arm of chromosome 17 (17p11.2). At least 11 distinct mutations have been identified. Without a functioning fatty aldehyde dehydrogenase enzyme, the  body is unable to break down medium- and long-chain fatty aldehydes which then build up in the membranes of the skin and brain. This condition is inherited in an autosomal recessive pattern. Diagnosis. Diagnosis is made with a blood test which sees if the activity of the fatty aldehyde dehydrogenase enzyme is normal. Gene sequencing can also be used, which can additionally be used by would-be parents to see if they are carriers. Treatment. The ichthyosis is usually treated with topical ointment. Anti-convulsants are used to treat seizures and the spasms may be improved with surgery. Eponym . It was characterized by Torsten Sjögren and Tage Konrad Leopold Larsson (1905–1998), a Swedish medical statistician. It should not be confused with Sjögren's syndrome, which is a distinct condition named after a different person, Henrik Sjögren.