Clinical presentation, immunohistologic features, molecular confirmation, and prenatal diagnosis of surfactant protein B (SP-B) deficiency.

We report a female full-term infant with fatal respiratory failure of early onset due to inherited SP-B deficiency. Lung biopsy was performed at 18 da ys after birth, with histopathological characterization indicating congenit al alveolar proteinosis. Immunohistochemical studies of lung tissue reveale d the absence of SP-B and the presence of intra-alveolar SP-A normal quanti ties. Analysis of genomic DNA showed homozygosity for the 121ins2 mutation of the SFTPB gene. The infant died 21 days afterbirth. Both parents were he terozygotes for the mutation. Chorionic villus sampling was performed at th e first trimester of the following pregnancy. Restriction analysis of ampli fied fetal DNA, studies of microsatellite segregation and direct sequencing led to the diagnosis of homozygosity for the parental wild-type allele. Th e diagnosis of congenital SP-B deficiency should be suspected whenever an e arly and acute respiratory failure in a term or near-term infant does not r esolve after five days of age: diagnostic confirmation can be easily and ra pidly obtained with the analysis of genomic DNA and immunohistochemical cha racterization of lung tissue. (C) 2000 Editions scientifiques et medicales Elsevier SAS.