User:Dr. Malik Magrabi

Larsen Syndrome (Dr. S. A. Malik Magrabi)

(ref.: SMITH’S- Recognizable Patterns of Human Malformation)

Multiple Joint dislocation, Flat facies, short fingernails

Etiology

Autosomal dominant is the most commonly reported mode of inheritance, autosomal recessive inheritance has also been suggested. Mutations in the gene encoding Filamin B (FLNB) localized to chromosome 3p14 are responsible for autosomal dominant Larsen Syndrome. FLNB seems to have an important role in vertebral segmentation, joint formation, and endochondral ossification.

Abnormalities

Facies: flat, with depressed nasal bridge and prominent forehead, hypertelorism; cleft palate.

Joints: dislocation of elbows, hips, knees and wrists, with dysplastic epiphyseal centers developing in childhood.

Hands: long, non-tapering fingers with spatulate thumbs, short nails, short metacarpals and multiple carpal ossification centers.

Feet: talipes equinovalgus or varus. Delayed coalescence of the two calcaneal ossification centers.

Spine: cervical kyphosis; spina bifida and hypoplastic bodies of cervical vertebrae; scoliosis, wedged vertebrae, lordosis, and anomalies of posterior elements of thoracic spine;  dysraphism, spondylolysis, and scoliosis of lumbar spine; spina bifida occulta of sacral spine.

Comment

A rare lethal form of this disorder has been described. The principal features include flat facies, cleft soft palate, redundant neck skin, multiple joint dislocations, rhizomelic shortening of the upper limbs, hypoplastic vertebral bodies. Death is secondary to pulmonary hypoplasia.