Larsen syndrome (LS) is one of the more uncommon genetic disorders, affecting only one out of 100,000 individuals. It is also congenital, which means the disorder is present from birth. Dr. Joseph Larsen, an orthopedic surgeon, first documented the occurrence of the syndrome in the 1950s. He observed more than five patients bearing the same unusual characteristics in their joints, limbs, and facial structure.
Common symptoms and characteristics of Larsen syndrome are the congenital dislocations of joints and deformities in the hands and feet. Both of these may result to hypermobility, an abnormal ability to over-extend and bend the joints. Babies often have limp muscles, which makes them appear rag doll-like. Another common feature is brachycephaly, or the “flat head syndrome.” People with this symptom have broader foreheads, widely-separated eyes, and a flattened nose bridge.
Other symptoms associated with Larsen syndrome are cleft palate, congenital heart problems, and a small stature. In some cases, a patient can have an abnormal spine curvature, respiratory problems, and mental retardation. Some patients with mild to moderate cases of Larsen syndrome do not possess all symptoms, but usually have the telltale features in the face and the limbs. Severe cases, however, can lead to the baby’s early death.
Larsen syndrome is an autosomal dominant congenital disorder, which means it only takes one defective copy of the gene for the disorder to be inherited. Just one parent with a mutated gene is enough to pass the same disorder to her child. Still, there are cases that reveal the disorder can also be in a recessive form, in which the offspring requires two affected genes to acquire Larsen syndrome. Rarer cases have even reported unaffected parents giving birth to affected children. Offspring of an affected parent have a 50-percent chance of inheriting the same mutated gene.
Studies show that Larsen syndrome results from a mutated protein called Filamin B (FNLB) located in a human’s chrosome 3. FNLB is partly responsible for the proper development of the skeleton. So far, no other genes have been found to affect a person with the disorder.
Larsen syndrome cannot be cured, but its symptoms can be treated and constantly monitored. Physical therapy can ease problems experienced in the joints, limbs, and spine, while surgery can reconstruct a cleft palate and fix heart problems. Breathing apparatuses and supplementary oxygen can help a patient with respiratory problems. Affected patients can have a normal life expectancy with constant care and treatment.