Aberrant SP‐B mRNA in lung tissue of patients with congenital alveolar proteinosis (CAP)

Abstract

Mutations in the surfactant protein (SP)-B gene are responsible for SP-B deficiency in congenital alveolar proteinosis (CAP) (Nogee et al. J Clin Invest 1994: 93: 1860-1883; Lin et al. Mol Genet Metab 1998: 64: 25-35; Klein et al. Pediatrics 1998: 132: 244-248; Ballard et al. Pediatrics 1995: 96: 1046-1052). The multigenerational consanguineous pedigree under study does not carry any of the known mutations, although this pedigree had 14 infant deaths following respiratory distress at birth. Immunostaining of the lungs from three such infants revealed decreased or absent SP-B. By sequencing of SP-B exons, exon-intron junctions, and the 5' and 3' flanking regions, nine polymorphisms were found in this pedigree, but none of them could explain the observed SP-B deficiency. Further analysis of SP-B mRNA by reverse transcription-polymerase chain reaction from paraffin-embedded lung tissue of CAP patients showed that SP-B mRNA is not intact. Although the sequence of mRNA from exon 1-exon 7 and from exon 8-exon 10 could be amplified, the region between exons 7 and 8 could not. From fluorescence in situ hybridization of the short arm of chromosome 2p, only 2 signals were identified, eliminating the possibility of translocation as the cause of the SP-B mRNA aberrance. Although the nature of the genetic basis of SP-B deficiency in this family is currently unknown, the existence of aberrant SP-B mRNA may, at least in part, be responsible for the SP-B deficiency in this pedigree.

The Importance of Surfactant on the Development of Neonatal Pulmonary Diseases

“…Such an alteration eliminates a potential site of glycosylation and is associated with certain pulmonary pathologies. 44 WANG et al 57 confirmed the existence of an N-linked glycosylation site at the terminal portion of SP-B gene. The T allele of the polymorphism 1580 (C/T) does not have the N-linked glycosylation site at the N-terminal fragment, and it is considered a protector factor regarding RDS, whereas the allelic variant C, which contains the recognition N glycosylation site of the fragment N-terminal, is a risk factor for chronic obstructive pulmonary disease (COPD) and ARDS.…”

“…After 2 years, Lin et al published a study of a family with a history of 14 newborn deaths due to early respiratory insufficiency. 44 The immunohistochemistry of the lung from 3 of these children showed a decrease or absence of SP-B expression. Nine polymorphisms were found in this family, but it was not possible to attribute any of them to the SP-B deficiency.…”

Surfactant protein B gene polymorphism in preterm babies with respiratory distress syndrome

“…Although it is located outside the protein translation site, this region can somehow impact gene expression and/or protein function (24).…”

“…For amplification of the segments that span the polymorphisms mentioned previously, we used previously described primers and protocols (23,24). All primers used are listed in Table 2.…”

“…The genotypes were defined based on the analysis of the PCR products obtained from the restriction enzyme reactions [PCRbased converted restriction fragment length polymorphism (cRFLP)], as described by Lin et al (23,24). Six microliters of the second PCR product was subjected to digestion with the restriction enzymes ApalI, HinfI, DdeI, and BfaI according to manufacturer specifications.…”