Updated 2006-01-19 by Juliana Leite, MD

Original text  1999-05-19 Philippe Jeanty, MD, PhD & Sandra R Silva, MD

Definition: This syndrome consists of skeletal dysplasia with multiple joint dislocations and short stature and abnormal facial features. There are two forms of the syndrome: a lethal and a nonlethal form. The lethal form is usually fatal due to pulmonary hypoplasia.

Synonyms: None.

Incidence: It is a rare anomaly with an estimated incidence of 1/100.000 births.

Etiology: Both autosomal-dominant and autosomal-recessive patterns of inheritance have been reported.

Pathogenesis: Generalized mesenchymal disorder involving connective tissues due to a decreased alpha-1/alpha-2 chain ratio in type I collagen (1).

Diagnosis: Prenatal diagnosis of Larsen syndrome is difficult and a review of the literature revealed only 5 previous cases (1). The abnormal joint with dislocations (hip dislocation, genu recurvatum, club hands from accessory carpal bones, clubfeet) can be associated with rhizomelic shortening of the upper extremities and with hypoplastic fibula. A coronal cleft in the vertebral body can also be recognized. At the level of the face, a low nasal bridge, frontal bossing, micrognathia, and hypertelorism can be observed. The neurological defects associated with Larsen syndrome include agenesis of the corpus callosum, hydrocephaly and hearing defects.

Associated anomalies: Some associated anomalies have also been reported including cleft palate, cervical spine instability, cardiac defects and pulmonary hypoplasia.

Genetic anomalies: The gene locus is at 3p21.1-p14.1.

Differential diagnosis: It has to be differentiated from the congenital genu recurvatum (CGR) (2), arthrogryposis multiplex congenital, Pena-Shokeir phenotype and cerebro-oculo-facio-skeletal syndrome. In the absence of familial history, these patients are usually identified as having arthrogryposis.

Prognosis: When recognized, the tracheomalacia, pulmonary insufficiency, and vertebral instability (cervical kyphosis from marked hypoplasia of one or two vertebral bodies—usually the fourth or fifth cervical vertebra) can be managed to improve the prognosis but probably only for the nonlethal form.

Management: Termination of pregnancy can be offered before viability. Standard prenatal care is not altered when continuation of the pregnancy is chosen. Confirmation of diagnosis after birth is important for genetic counseling.

References:

1: Shih JC, Peng SS, Hsiao SM, Wang JH, Shyu MK, Lee CN, Hsieh FJ. Three-dimensional ultrasound diagnosis of Larsen syndrome with further characterization of neurological sequelae. Ultrasound Obstet Gynecol 2004;24(1):89-93

2: Gorincour G, Chotel F, Rudigoz RC, Guibal-Baggio AL, Berard J, Pracros JP, Guibaud L. Prenatal diagnosis of congenital genu recurvatum following amniocentesis complicated by leakage. Ultrasound Obstet Gynecol 2003;22(6):643-5