Patterned expression in familial Klippel-Feil syndrome.

Klippel-Feil syndrome (KFS) is characterised by congenital fusion of vertebrae within the rostral spine. The first KFS gene (SGM1) locus identified on chromosome 8 segregates with vertebral fusions and associated vocal impairment within the KF2-01 family (Clarke et al., '94, '95). Here, we describe the unique pattern of variable phenotypic expression within the KF2-01 family. The pattern of anomalies revealed a cumulative, rostrocaudal graded sequence of skipped vertebral fusions. This fusion pattern presents striking similarities with the mutant phenotype and gene expression profile of the Drosophila segment polarity gene engrailed.