Larsen syndrome was first described in 1950 by an orthopaedic surgeon, Joseph Larsen. He noticed that a number of his patients shared common features including multiple dislocations of the major joints (wrists, elbows, hips and knees), deformities of the feet and an unusual facial appearance characterised by a flat nasal bridge, wide-spaced eyes, and a prominent forehead.

The wide range of features associated with Larsen syndrome include abnormalities of the growth centres and length of the bones. This leads to short stature, Scoliosis, short stubby fingers, broad thumbs, short metacarpals (the bones between the wrist and the base of the fingers) and foot deformities. Individuals may also have abnormalities of the cervical spine (the seven bones of the top end of the backbone that form the neck) leading to cervical kyphosis (forward curving of the spine); the thoraco-lumbar spine (the twelve bones below the cervical spine together with the five bones of the lower back) leading to spina-bifida and scoliosis; cleft lip and/or palate; tracheomalacia (softening of the cartilages in the trachea); difficulties in swallowing and breathing; and poorly developed kidneys (see entry, Kidney disease), ureters and urinary bladder. Mixed hearing loss (see entry, Deafness) has been reported.

There is variation in the severity of the syndrome. A rare lethal form has been described but is likely to be a different disorder.

Treatment of Larsen syndrome varies according to an individual's specific features. Joint abnormalities may require prolonged orthopaedic treatment including special exercises, casting, braces, or surgery. Abnormal spinal segmentations may be treated either by use of a brace or surgical procedure. Early diagnosis of cervical kyphosis followed by operative stabilisation may help to avoid neurological side effects. Surgery of the inner ear bones may be possible and may be treated with hearing aids. Cleft palate or cleft lip may be managed with speech therapy or surgical procedures. Respiratory problems can be treated with chest physiotherapy, tracheotomy (opening made in the front of the neck so that air can be drawn in), and the assistance of a ventilator. Given the wide range of features associated with Larsen syndrome, a number of different specialists may be involved in the management of the condition.

Larsen syndrome is thought to be caused by a generalised embryonic connective tissue disorder during gestation. It is categorised as one of a number of connective tissue disorders including Ehlers-Danlos syndrome, Brittle Bone Disease/Osteogenesis Imperfecta and Marfan syndrome.

Inheritance patterns
Larsen syndrome may be inherited as either an autosomal dominant trait or an autosomal recessive trait. More commonly, it is inherited as an autosomal recessive trait. Changes (or mutations) in a gene on chromosome 3 are thought to be responsible for the dominant form of Larsen syndrome. Changes in genes on either chromosome 1 or chromosome 6 are thought to be associated with the autosomal recessive form of Larsen syndrome.

It is not possible to categorise, on the basis of clinical features alone, the inheritance pattern of Larsen syndrome in an individual case, either as an autosomal dominant trait or an autosomal recessive trait. However, features such as syndactyly, cleft palate, genital anomalies and severe short stature and milder 'flat face' appearance are more commonly associated with the recessive form of the condition. The variability of the effects of this condition make genetic counselling for Larsen's syndrome complex.

Prenatal diagnosis
Ultrasonographic diagnosis may be possible prenatally for features such as dislocations of specific parts of the body. Confirmation of a diagnosis of Larsen syndrome after birth is important for genetic counselling.

Medical text written October 2003 by Contact a Family. Approved October 2003 by Professor M Patton, Professor of Medical Genetics, St George's Hospital Medical School, London, UK.

Further Online Resources
Medical texts in The Contact a Family Directory are designed to give a short, clear description of specific conditions and rare disorders. More extensive information on this condition can be found on a range of reliable, validated web sites and links to them are included in the CD-ROM version of this Directory. Further information on these resources can be found in our Medical Information on the Internet article.

There is no support group for Larsen Syndrome. Cross referrals to other entries in the Contact a Family Directory are intended to provide relevant support for these particular features of the disorder. Organisations identified in these entries do not provide support specifically for Larsen Syndrome . Families can use Contact a Family's Freephone Helpline for advice, information and, where possible, links to other families. Contact a Family's web-based linking service Making Contact.org can be accessed at http://www.makingcontact.org