GDF3 and Klippel-Feil syndrome 1, autosomal dominant: KFS1 (OMIMs 118100) is caused by a mutation in the Growth Differentiating Factor-6 (GDF6) gene, whereas KFS3 (OMIM 613702) has a mutation in the GDF-3 (GDF3) gene.6,7 Some KFS cases are caused by chromosomal rearrangement.8–10