Aims : to present the main process and challenges of genetic data interpretation; to list the main genetic diagnostic tools and their limitations; to provide the audience with key tips to read a genetic report. to discuss importance of genotyping for three model monogenic diseases that can affect newborns or occur later in life (cystic fibrosis, surfactant disorders and primary ciliary dyskinesia): to illustrate the phenotype-genotype correlation diversity and gene/mutation(s) distinct consequences at the cell level; to explain the consequences of molecular diagnosis on vital prognosis at birth, follow-up, lung cancer risk later in life and genetic counselling; to explain how genotypes connect with current personalised treatments and their development.