Novel clinical and genetic findings in Laurin-Sandrow Syndrome: a case report

Introduction: Laurin-Sandrow syndrome is a very rare developmental disorder characterized by polysyndactyly of the hands and feet, as well as nasal anomalies. Often, there is associated ulnar and/or fibular duplication. It is caused by microduplications on chromosome 7q36 that encompass the Sonic hedgehog limb enhancer region, the zone of polarizing activity regulator sequence (ZRS). Case presentation: We describe here an individual with triplication encompassing the ZRS region. In addition to the other characteristic features of this condition, he has an unerupted single central maxillary incisor tooth. Conclusion: Laurin-Sandrow syndrome is caused by interrupted signaling of Sonic hedgehog pathway due to duplications encompassing its enhancer region (ZRS) on chromosome 7q36. ZRS plays a crucial role in limb development by regulating the Sonic hedgehog signaling. Nasal anomalies are well recognized features of Laurin-Sandrow syndrome. Single median maxillary central incisor has not been described in Laurin-Sandrow syndrome, but it is associated with Sonic hedgehog signaling interruption. The presence of nasal anomalies and dental abnormality in Laurin-Sandrow syndrome may suggest a potential role of ZRS in craniofacial development beyond its known role in limb development.