Okihiro syndrome

Duane-Radial Ray Syndrome

Clinical Characteristics

Ocular Features:

Most individuals have features of Duane’s anomaly, sometimes unilaterally. Optic pallor with poor vision has been described in well-studied patients who also had thinning of the retinal nerve fiber layer. The optic disk may appear hypoplastic. Visual evoked potentials and pattern ERG amplitudes are decreased.

Other less common ocular features are microcornea, microphthalmia, ophthalmoplegia, hypertelorism, cataracts, epicanthal folds, colobomas, and chorioretinal scars.

Systemic Features:

The systemic features are inconsistent (variable expressivity) with most patients having some variation of hypodactyly, polydactyly, syndactyly, and malformation of the hands. The thumb is the most common digit involved and this is often associated with thenar hypoplasia. Other skeletal features of the radial ray syndrome including absence of the radial and ulnar bones are variably present. Hearing loss is described as sensorineural in etiology but malformations of the pinnae and external meatus are sometimes present.

Kidney anomalies include horseshoe malformations, abnormal rotation, ectopia, small size, vesicoureteric reflux, and pelvicalyceal dilatation.

Genetics

This is an autosomal dominant disorder due to heterozygous mutations in the SALL4 gene (20q13.2).

This syndrome is sometimes confused with the Holt-Oram syndrome but the latter is the result of mutations in a different gene and lacks ocular and renal abnormalities. Duane syndrome 1 and 2 may also occur as isolated conditions.

The considerable clinical heterogeneity has led to alternate titles for this syndrome. For example, what is sometimes called the IVIC syndrome (147750) with similar features is also caused by mutations in this gene. Duane-radial ray syndrome has also been called Okihiro syndrome.

Pedigree:

Autosomal dominant

Treatment

Treatment Options:

Treatment is symptomatic in most cases although reconstructive surgery may be helpful for severe hand deformities. Low vision aids may be beneficial.

References

Article Title:

Ocular manifestations (strabismus: duane syndrome; and retinal nerve fiber hypoplasia) in okihiro syndrome (duane radial ray syndrome)

Garcia-Martin E, Pinilla I, Almarcegui C, Fernandez J, Engle EC, Ramos FJ. Ocular manifestations (strabismus: duane syndrome; and retinal nerve fiber hypoplasia) in okihiro syndrome (duane radial ray syndrome). Binocul Vis Strabolog Q Simms Romano. 2012;27(4):235-42.

PubMed ID:

23234485

IVIC syndrome is caused by a c.2607delA mutation in the SALL4 locus

Paradisi I, Arias S. IVIC syndrome is caused by a c.2607delA mutation in the SALL4 locus. Am J Med Genet A. 2007 Feb 15;143(4):326-32.

PubMed ID:

17256792

SALL4 deletions are a common cause of Okihiro and acro-renal-ocular syndromes and confirm haploinsufficiency as the pathogenic mechanism

Borozdin W, Boehm D, Leipoldt M, Wilhelm C, Reardon W, Clayton-Smith J, Becker K, M?ohlendyck H, Winter R, Giray O, Silan F, Kohlhase J. SALL4 deletions are a common cause of Okihiro and acro-renal-ocular syndromes and confirm haploinsufficiency as the pathogenic mechanism. J Med Genet. 2004 Sep;41(9):e113.

PubMed ID:

15342710

Duane radial ray syndrome (Okihiro syndrome) maps to 20q13 and results from mutations in SALL4, a new member of the SAL family

Al-Baradie R, Yamada K, St Hilaire C, Chan WM, Andrews C, McIntosh N, Nakano M, Martonyi EJ, Raymond WR, Okumura S, Okihiro MM, Engle EC. Duane radial ray syndrome (Okihiro syndrome) maps to 20q13 and results from mutations in SALL4, a new member of the SAL family. Am J Hum Genet. 2002 Nov;71(5):1195-9.

PubMed ID:

12395297

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