An eleven year old male child born to a nonconsanguinous couple presented with multiple joint dislocation since birth. He had mild motor delay. Examination showed presence of short stature. There was no microcephaly. He had flat facies, prominent forehead, depressed nasal bridge, and hypertelorism (Fig. 1). He had bilateral rhizomelic shortening of upper limbs, spatulate and dislocated thumbs (Fig. 2), bilateral elbow, ankle, and hip dislocation (Fig.3). Examination of parents did not reveal any features of Larsen syndrome. X-rays of long bones showed presence of bilateral tibio-femoral and patellar dislocation at knees and dislocation at hip, ankles and thumbs. He also had hypoplastic fibula on right side. X-ray spine showed presence of short and thick pedicles, kyphosis and hypoplastic superior articular facets. There was no atlanto axial dislocation. Child was referred to orthopedic surgeon for aggressive orthopedic management.

Fig. 1 Facial dysmorphism. Note flat nasal bridge and prominent forehead.	Fig. 2 Note dislocations at thumb.	Fig. 3 Multiple dislocations at large joints.

Larsen syndrome (OMIM 150250) is a complex syndrome with genetic heterogeneity, and with both autosomal dominant and autosomal recessive patterns of inheritance. Mutations in gene encoding filamin B (FLNB) result in Larsen syndrome. This gene has an important role in vertebral segmentation, joint formation and endochondral ossification and is also mutated in atelosteogenesis types I and III, and in spondylocarpotarsal syndromes. Autosomal dominant form is characterized by flat facies, joint hypermobility, congenital multiple joint dislocations, especially of the knees and talipes equinovarus. The mid-face is hypoplastic with a depressed nasal bridge. Cleft palate may be present. Osteoarthritis involving large joints and progressive kyphoscoliosis are potential complications. Airway obstruction caused by tracheomalacia and bronchomalacia may be life threatening. All affected individuals should be evaluated for cervical spine instability and caution should be taken during anesthesia because of the mobile arytenoids cartilage as well as the potentially dangerous spinal anomalies. Important differential diagnosis is Otopalatodigital syndrome type 1 characterized by pugilistic facies, hearing loss, paddle shaped metatarsal bones, no juxta calcaneal bones and no supernumerary carpal bones.

Neerja Gupta,
Madhulika Kabra,
Genetics Unit, Department of Pediatrics,
AIIMS, New Delhi 110 029, India.
E-mail: [email protected]