Surfactant protein B deficiency: the RespiRare cohort.

Childhood interstitial lung diseases (chILD) are rare and usually severe disorders. Among them, very rare cases of surfactant protein (SP)-B deficiencies have been reported so far and are usually associated with fatal forms of chILD. The RespiRare network allows the collection of precise phenotypic and genotypic information. This study that reports a series of 11 SP-B-deficient patients underscores two key observations: patients with severe loss-of-function variants associated with SP-B complete deficiency presented symptoms at birth and died at a median age of 1 month; and extremely rare cases of hypomorphic variants with partially preserved SP-B function may allow survival.