Notomelia and related neural tube defects in a baby born in Niger: case report and literature review

Abstract

Introduction: Notomelia associated with neural tube defects are rare diseases.

Case report: A baby was born in Niger with multiple congenital embryonic malformations on the posterior midline. The most rostral malformation was an accessory limb (polymelia) at the level of the lumbar vertebrae composed of two long bones, a foot and three toes. Accessory male genitalia were present at the base of this malformed accessory limb which had no apparent motor or sensory innervation. The second malformation was a sacral vestigial appendage with an adjacent dermal sinus opening onto the posterior midline and extending internally to the dura through a defect of the vertebral arches. From the published literature and this particular case, we conclude that notomelia is a rare clinical sequela of a neural tube defect (NTD) and is correctly classified as a dysraphic appendage.

Conclusion: The recent occurrence of three similar cases in the same ethnic group from Niger, three from consanguineous parents, suggests that genetic factors are likely to contribute significantly to the genesis of this syndrome, consistent with a recent report that mutation of the bovine NHLRC2 gene resulting in a V311A substitution at a highly conserved locus in the NHLRC2 protein is, when homozygous, causally associated with several forms of polymelia including notomelia, with heteropagus conjoined twinning and with other NTD-related embryonic malformations. Detailed genome-wide studies of children with dysraphic appendages are indicated.

Keywords: Neural tube defect; Notomelia; Polymelia.