الفهرس 
RESPIRATORY ESPIRATORY ESPIRATORY ESPIRATORY ESPIRATORY ESPIRATORY DISTRESS ISTRESS ISTRESS ISTRESS SYNDROMEYNDROME YNDROME YNDROMEOnly 14 pages are availabe for public view
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Abstract
RDS is a common, devastating, clinical syndrome of acute lung injury. It constitutes one of the main causes of respiratory morbidity in children less than1 year of age despite the improvement in neonatal survival rates. 5%-25% of the newborns affected by RDS will develop chronic pulmonary diseases.
RDS occurring most often 10%-15% in premature infants with low birth weight, however, not all infants are at equal risk. It remains a major cause of perinatal morbidity and mortality in extremely premature infants.
RDS is mainly caused by deficiency of pulmonary surfactant. Lung surfactant consists of a unique and complex mixture of lipids (85-90%) and specific proteins (10%) four surfactant specific proteins have been discovered, called SP A, B, C and D.
SP-B is one of the most important component of the surfactant system, its gene is located on the short arm of the chromosome 2 extends for approximately 9.5 kilobases and contains 11 exons. Although the SP-B accounts for 1-2% of SP, yet it is crucial in the maintenance of normal surfactant function, exerts an antibacterial effect and may play an important local immunoprotective role in the lungs. SP-B gene is known to be polymorphic and the presence of polymorphisms has been implicated in RDS. The study of the genetic variations of SP-B can help understanding individual variability in the susceptibility to the development of pulmonary pathologies and can be used as valuable markers in the mapping of several pathologies, particularly for the RDS.
Several studies described C1580T polymorphism that potentially alter the function of this protein and could influence the development of RDS.
In view of such data, the aim of this study was designed to elucidate the association between SP-B gene polymorphism and RDS among preterm neonates with special emphasis on its impact on clinical status, severity and outcome. That could be used as markers in population and family base association studies.
The present study was conducted on 120 neonates; group A, 40 preterm neonates with RDS, group B, 40 preterm apparently healthy neonates and group C, 40 full term apparently healthy neonates with matched ages and sex serving as controls. Molecular study of SP-B gene polymorphism was carried out using allelic discrimination by PCR and REFLP. 27.5% of the studied patients showed mild – moderate severity while, 72.5% were severely ill. Moreover 47.5% were discharged uncomplicated, 17.5% died and 35% complicated by Air leak (28.4), IVH (21.5%), CLD (21.5%), PDA (14.3%) and NEC (14.3%).
The results of this study revealed:
The C allele frequency of SP-B (C1580T) was higher in RDS patients than preterm and full term controls.
The T allele was at lower frequency in patients with RDS than controls.
Higher frequency of CC genotype in RDS patients than preterm and fullterm controls.
Lower frequencies of TT and CT genotypes were found among patients group compared to controls.
CC genotypes were higher in males versus females with statistically significant difference among RDS patients.
Higher frequency of TT and CT genotypes than CC genotype in mild -moderate RDS patients, while the frequency of CC genotype was the highest among the sever RDS with statistical significant difference regarding the severity of RDS.
Higher frequency of the CC genotype among advanced stages of x-ray grading with statistical significant difference.
TT and CT genotypes were the most commonly present in the discharged uncomplicated neonates. They were of good prognosis, where as the frequency of CC genotype frequencies were of bad prognosis and they were higher among dead cases showing statistical significant difference.
Higher TT genotypes among RDS patients with –ve family history were noted while the CC frequency was higher in patients with +ve family history with a statistical significant difference.