The Association of an Epibulbar Dermoid and Duane Syndrome in a Patient with a SALL1 Mutation (Townes-Brocks Syndrome)

Abstract

Introduction: Townes-Brocks Syndrome (TBS) is an autosomal dominant condition characterized by renal, anal, ear and thumb anomalies caused by SALL1 mutations. Ocular manifestations reported have included congenital cataracts, unilateral microphthalmia, optic nerve atrophy, and unilateral visual loss with bilateral Brushfield Spots. Iris and chorioretinal colobomata were described in one individual whose daughter had Duane syndrome. Methods: We present a case of TBS with a proven SALL1 mutation associated with unique ophthalmic features. Case Report: The first child of healthy unrelated parents was born after an uncomplicated pregnancy with multiple features consistent with TBS. The patient was heterozygous for a pathogenic SALL1 gene mutation c826C > T (pR276X). The child had an epibulbar dermoid and left Type 1 Duane syndrome. He also had tearing when he ate food (crocodile tears). Discussion: This case adds to the current knowledge of ophthalmic associations with SALL1 mutations; features characteristic of SALL1 mutations and others more commonly associated with SALL4 mutations (2) (epibulbar dermoid and Duane) being present. Truncated SALL1 protein alters the localization of full length SALL4 providing a theoretical mechanism for these associations, alternatively SALL1 mutations cause associated eye problems more directly. The possibility of chance association cannot be excluded. Our case is only the second we have found with a SALL1 mutation and TBS with Duane syndrome and the first to also have an epibulbar dermoid. The mutation present is that most commonly associated with TBS. Conclusion: This case increases the demand to examine all children TBS for ophthalmic abnormalities.