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.

In the original publication of this article, we wrote "Although the allele prevalence of this V311A NHLRC2 mutation in the registered Angus cattle population was only 16% at the time, eleven of 13 consecutive cases with NTD related lesions were homozygous for the NHLRC2 mutation, demonstrating a causal association (Denholm et al., 2015)."In fact, Denholm et al. (2015) stated that the allele prevalence in the registered Angus cattle population in Australia in which the eleven consecutive NTD cases were observed was 7% at the time. (Correlation between the detected NHLRC2 mutation and the observed NTD related phenotypes is higher at the lower (corrected) allele prevalence value.)The online version of the original article can be found at http://dx

This type of tumor is extremely rare and is only the second case that has been reported at this exact location. This could be the so-called céphalomélie described by Isidore Geoffroy Saint-Hilaire in a duck in his famous Treatise of Teratology (1836). The cause of this malformation is still a matter for debate.