By Colin Kellaher

Vertex Pharmaceuticals Inc. on Wednesday said the European Commission approved the expanded use of Kalydeco to include children and adolescents with cystic fibrosis who have the R117H mutation in the cystic fibrosis transmembrane conductance regulator gene.

The Boston drug maker said the approval covers patients between the ages of six month and 18 years who have the mutation, the most common residual function mutation underlying the genetic disease that causes persistent lung infections.

Vertex said the label extension makes about 500 young patients in Europe eligible for Kalydeco, which was already approved in Europe for adults with the R117H mutation and for children with several other mutations.

Write to Colin Kellaher at colin.kellaher@wsj.com