Sjögren - Larsson Syndrome (SLS)
What is Sjögren - Larsson Syndrome?
Sjögren-Larsson Syndrome (SLS) is an inherited disorder characterized by skin abnormalities (ichthyosis) typically present at birth or within the first year of life and neurologic abnormalities. Ichthyosis is a scaling, redness and thickening of the skin. Other features include sensitivity to sunlight and shedding of the skin on the palms of the hands and the soles of feet. Neurologic signs usually appear around 1-2 years of age and may include muscle spasms and developmental delays. Seizures typically develop later in childhood.
The key symptoms of SLS include:
- Intellectual disability
- Low muscle tone
- Increased muscle tone in the arms and or legs
- Thick scaly skin present at birth (ichthyosis)
- Eye abnormalities
- Speech difficulties
- Dental problems
- Bone abnormalities
How many people have Sjögren - Larsson Syndrome?
SLS is estimated to occur in 1 per 250,000 births worldwide and higher in certain geographic locations. There is also an increased frequency of SLS in two counties in Sweden (Vasterbotten County and Norrbotten County).
What causes Sjögren - Larsson Syndrome?
SLS is caused by a mutation or change in the ALDH3A2 gene which makes the enzyme fatty aldehyde dehydrogenase (FALDH). FALDH is involved in the transformation of fatty alcohols to fatty acids in our body. The gene mutation results in an inactive enzyme, accumulation of fatty alcohols and decreased production of fatty acids and fatty acid-derived chemicals in the body. This is believed in turn to cause disruption in the skin-water barrier, leading to increased water loss and causing dry, scaly skin, and to neurological abnormalities.
SLS is an inherited autosomal recessive disorder. Affected individuals inherit two copies of the mutated or changed ALDH3A2 gene, one from each parent. Therefore the parents are "carriers" of SLS, meaning that they have one normal functioning copy and one non functioning copy of the gene. With each pregnancy, carriers of SLS have a 1 in 4 or 25% chance of having a child with SLS.
How is Sjögren - Larsson Syndrome diagnosed?
SLS is diagnosed by measuring deficient FALDH enzyme activity in cultured skin cells or by genetic testing of the ALDH3A2 gene.
What is the treatment for Sjögren - Larsson Syndrome?
There is no curative treatment for SLS. The symptomatic treatment of ichthyosis may include the use of retinoids, lotions and keratolytic agents (peeling agent that softens and sheds the outer layer of skin). All other treatments are symptomatic