Mesomelic and rhizomelic short stature: The phenotype of combined Leri-Weill dyschondrosteosis and achondroplasia or hypochondroplasia.

We studied two children with combined genetic skeletal disorders. Both had Leri-Weill dyschondrosteosis (LWD); one also had achondroplasia and the other had hypochondroplasia. Both had severe short stature and evidence of rhizomelia and mesomelia as well as other phenotypic features of their individual genetic disorders. Achondroplasia was due to the G380R FGF3R mutation and hypochondroplasia to a N540K mutation in the same gene. The patient with hypochondroplasia had a heterozygous SHOX deletion; no SHOX mutation was identified in the child with achondroplasia. The phenotypes of combined LWD and achondroplasia or hypochondroplasia appeared to be less than additive, suggesting that SHOX and FGFR3 act on overlapping pathways of bone growth and development.