Overall, the SP-A1 6A4 or/and SP-A2 1A5 haplotype was present in 20 newborns with RDS (35.7%), resulting in a 4.2-fold (1.60-11.0) higher probability of RDS in carriers.
Single-nucleotide polymorphisms (SNPs) in SP-A1 and SP-A2, genes encoding SP-A, have been associated with susceptibility to respiratory distress syndrome, COPD, and pulmonary infections.
The difference in RDS concordance rates between the monozygotic (MZ) and dizygotic (DZ) twin pairs as evidence of a genetic influence was evaluated, and the SP-A and SP-B genes were investigated for potential associations with the susceptibility to RDS.
The SP-A 6A2 allele in the SP-B Thr131 background predisposed the smallest singleton infants to RDS, whereas near-term multiples were protected from RDS.
Allelic variations of the SP-A and SP-B genes have been shown to be important genetic determinants in individual susceptibility to RDS, which is a good general model for a multifactorial pulmonary disease resulting from complex interactions between several environmental and genetic factors.
The present family study provides strong support for a direct or indirect role of the SP-A alleles as genetic predisposers to RDS in premature infants.
Furthermore, one SP-A2 allele (1A0) shown to associate with low SP-A mRNA levels is found with higher frequency in a subgroup with respiratory distress syndrome.
SP-A and SP-B polymorphisms are found at a higher frequency in certain groups of patients with respiratory distress syndrome (RDS), and SP-B mutations are linked to the pathogenesis of congenital alveolar proteinosis (CAP).