SMOC1

Microphthalmia with Limb Anomalies

Clinical Characteristics
Ocular Features: 

Patients have either microphthalmia or anophthalmia which may be present unilaterally or bilaterally.  The MRI in several patients has revealed complete absence of the globes, optic nerves, chiasm, and optic tracts.  The eyelashes are often sparse with shortened palpebral fissures and broad lateral eyebrows.

Systemic Features: 

Global developmental delays, failure to thrive, and mild to moderate mental retardation are common.   Syndactyly, polydactyly, and oligodactyly with hypoplasia of the long bones are present to a variable degree.  Synostosis in the digits, ankles, and wrist is often seen.  A split hand (lobster-claw deformity) is variably present.  Other anomalies such as the kidneys (horseshoe kidney), undescended testes, anomalous venous circulation and deformed vertebrae have been reported.  The midface is often flattened.  A high palate, cleft lip, and mild scoliosis may be seen.

Genetics

This is an autosomal recessive disorder resulting from homozygous mutations in the SMOC1 gene (14q24.2) but there is some evidence of genetic heterogeneity as the disorder has been mapped to 10p11.23 in several families.  However, no causative mutations were found in this region.  Consanguinity among parents is common.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

There is no treatment in most cases for the ocular malformations.  Some of the limb anomalies may be surgically correctable.

References
Article Title: 

SMOC1 is essential for ocular and limb development in humans and mice

Okada I, Hamanoue H, Terada K, Tohma T, Megarbane A, Chouery E, Abou-Ghoch J, Jalkh N, Cogulu O, Ozkinay F, Horie K, Takeda J, Furuichi T, Ikegawa S, Nishiyama K, Miyatake S, Nishimura A, Mizuguchi T, Niikawa N, Hirahara F, Kaname T, Yoshiura K, Tsurusaki Y, Doi H, Miyake N, Furukawa T, Matsumoto N, Saitsu H. SMOC1 is essential for ocular and limb development in humans and mice. Am J Hum Genet. 2011 Jan 7;88(1):30-41.

PubMed ID: 
21194678

A locus for ophthalmo-acromelic syndrome mapped to 10p11.23

Hamanoue H, Megarbane A, Tohma T, Nishimura A, Mizuguchi T, Saitsu H, Sakai H, Miura S, Toda T, Miyake N, Niikawa N, Yoshiura K, Hirahara F, Matsumoto N. A locus for ophthalmo-acromelic syndrome mapped to 10p11.23. Am J Med Genet A. 2009 Mar;149A(3):336-42.

PubMed ID: 
19208380
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