Fig. 1

Patient 3 a manifested hypertelorism, up-slanted palpebral fissures, anteverted nares, prominent nasal bridge and overall impression of coarse facial features. She presented also partial skin syndactyly of toes 2–3, bifid hallux and clinodactyly of the 5th fingers (b, c). Patient 5 and patient 6 are monozygotic twin sisters with a highly variable clinical presentation of CFNS. While patient 5 presents with typical facial features of CFNS (d–g), patient 6 (h) shows a relatively mild phenotype (see Table 1 for details) that is not suggestive of CFNS. The family pedigree of monozygotic twins (f). The analysis of relatives was not possible because twins were adopted