Larsen Syndrome

Congenital dysmorphic syndrome associated with characteristic anomalies of face, hands, and feet, and multiple congenital dislocations. Spine, airway, and cardiac abnormalities are also present.

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Multiple Congenital Dislocation Syndrome.

Larsen Syndrome, Autosomal Dominant: Characterized by short stature, flat facies, prominent forehead, hypertelorism, cataracts, cleft lip/palate, congenital heart defects (e.g., aortic dilatation, atrial septal defect and ventricular septal defect), respiratory abnormalities (e.g., tracheal stenosis and malacia, bronchomalacia), and potentially severe cervical spine anomalies leading to spinal cord compression.

Larsen Syndrome, Autosomal Recessive: Characterized by multiple congenital dislocations, craniofacial abnormalities (e.g., prominent forehead, depressed nasal bridge, hypertelorism) and clubfeet. Other clinical features include cleft palate, hydrocephalus, and atlantoaxial joint and cervical spine abnormalities.

Larsen-like Syndrome (LRSL): Very rare disorder characterized by facial dysmorphism, multiple joint dislocations suggesting the presence of a Larsen syndrome but presenting as a partial trisomy 1q and partial monosomy 6p.

Larsen-like Lethal Syndrome: Characterized by multiple joint dislocations and neonatal death as a result of pulmonary insufficiency, laryngomalacia, tracheomalacia, and pulmonary hypoplasia.

Approximately 1:100,000 live births; both sexes affected equally. However, in La Réunion Island in the Indian Ocean, the incidence is 1:1500 all births.

The syndrome occurs sporadically. Most often it is inherited an autosomal dominant trait, although an autosomal recessive transmission has also been described. The responsible gene maps to 3p21.1-p14.1.

The exact mechanism is unknown, but it most likely is the result of an error in collagen synthesis.

Usually made by the typical clinical features of association of musculoskeletal abnormalities with a typical flat facies and the presence of a double ossification center in the calcaneum (see Clinical Aspects).

Differentiation between the recessive and the dominant form can be difficult because both show a wide clinical variability; however, the recessive form is generally more severe. The typical features include anomalies of the face (flat-profiled face with frontal bossing and depressed nasal bridge, hypertelorism, cleft palate), the spine (abnormal segmentation of vertebrae, cervical spina bifida occulta, hypoplastic cervical vertebrae with cervical instability, and progressive cervical kyphosis), the skeletal system (short stature, joint hyperlaxity with multiple congenital dislocations—most often knee, hip, elbow [radiohumeral and ulnohumeral]—an accessory ossification center in the calcaneus, syndactyly, and cylindrically shaped fingers with short end phalanges giving a pseudoclubbing aspect), the airway (hypoplastic lungs, cartilage anomalies resulting in decreased chest wall stability, floppy epiglottis, laryngotracheomalacia, and respiratory failure), and the heart (congenital [atrial septal ...