• Okihiro syndrome
• acro-renal-ocular syndrome

The Okihiro syndrome consists of Duane anomaly, radial ray defects, and deafness. There are similarities with the acro-renal-ocular syndrome in which there are radial ray and renal abnormalities and colobomas which mostly involve the optic nerve. Both malformation syndromes are dominantly inherited. We report two families with an overlapping phenotype, suggesting a common aetiology. The combination of optic nerve coloboma and renal disease is also seen in families with mutations of the PAX2 gene. We did not find any evidence of PAX2 involvement in our families.

The main features of the autosomal dominant Okihiro syndrome are radial ray defects of variable severity and Duane anomaly.^1,2 Sensorineural hearing loss and spinal and other skeletal abnormalities also occur, and polydactyly, hemifacial microsomia with skin tags, cardiac defects, and Hirschsprung disease have also been reported.^1,3–5 The radial ray defects may be associated with vascular abnormalities such as hypoplasia of the radial artery⁶ and abnormal nerve conduction studies with reduced or absent motor response from the median nerve.^1,6 The acro-renal-ocular syndrome, which is also autosomal dominant, consists of radial ray defects, renal anomalies, and ophthalmological abnormalities, mainly colobomas, but also microphthalmia, ptosis, and Duane anomaly.^7–12 There is considerable overlap between the two syndromes, and it has been suggested previously that they are one clinical entity.⁸ In addition, mutations in the PAX2 gene have been documented in patients with optic nerve colobomas and renal malformation.^13–15 There are also similarities to Wildervanck syndrome, Goldenhar syndrome, and thalidomide embryopathy. This can lead to considerable difficulties with classification in individual families. We describe four affected subjects in two new families with features of both Okihiro syndrome and the acro-renal-ocular syndrome and investigate the possibility of PAX2 involvement.