Genetic polymorphisms of hemostasis genes and primary outcome of very low birth weight infants

Genetics of bronchopulmonary dysplasia: An update

Bronchopulmonary dysplasia (BPD) is a multi-factorial disease that results from multiple clinical factors, including lung immaturity, mechanical ventilation, oxidative stress, pulmonary congestion due to increasing cardiac blood shunting, nutritional and immunological factors. Twin studies have indicated that susceptibility to BPD can be strongly inherited in some settings. Studies have reported associations between common genetic variants and BPD in preterm infants. Recent genomic studies have highlighted a potential role for molecular pathways involved in inflammation and lung development in affected infants. Rare mutations in genes encoding the lipid transporter ATP-binding cassette, sub-family A, member 3 (ABCA3 gene) which is involved in surfactant synthesis in alveolar type II cells, as well as surfactant protein B (SFTPB) and C (SFTPC) can also result in severe form of neonatal-onset interstitial lung diseases and may also potentially affect the course of BPD. This chapter summarizes the current state of knowledge on the genetics of BPD.

Genetic predictors of severe intraventricular hemorrhage in extremely low-birthweight infants

OBJECTIVE

To test associations between grades 3 or 4 (severe) intraventricular hemorrhage (IVH) and single nucleotide polymorphisms (SNPs) associated with coagulation, inflammation, angiogenesis, and organ development in an exploratory study.

STUDY DESIGN

Extremely low-birthweight (ELBW) infants enrolled in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network's (NRN) Cytokines Study were included if they had cranial ultrasound (CUS) and genotyping data available in the NRN Anonymized DNA Repository and Database. Associations between SNPs and IVH severity were tested with multivariable logistic regression analysis.

RESULT

One hundred thirty-nine infants with severe IVH and 687 infants with grade 1 or 0 IVH were included. One thousand two hundred seventy-nine SNPs were genotyped. Thirteen were preliminarily associated with severe IVH including five related to central nervous system (CNS) neuronal and neurovascular development.

CONCLUSION

Genetic variants for CNS neuronal and neurovascular development may be associated with severe IVH in premature infants.

Intraventricular hemorrhage in preterm babies

Germinal matrix-intraventricular hemorrhage (GM-IVH) is a major complication of prematurity and inversely associated with gestational age and birth weight. The hemorrhage originates from the germinal matrix with an immature capillary bed where vascularization is intense and active cell proliferation is high. It occurs in around 20% of very low-birth-weight preterm neonates. Germinal matrix-intraventricular hemorrhage is less common in females, the black race, and with antenatal steroid use, but is more common in the presence of mechanical ventilation, respiratory distress, pulmonary bleeding, pneumothorax, chorioamnionitis, asphyxia, and sepsis. Ultrasonography is the diagnostic tool of choice for intraventricular hemorrhage and its complications. Approximately 25-50% of the germinal matrix-intraventricular hemorrhage cases are asymptomatic and diagnosed during routine screening. These cases are usually patients with low-grade hemorrhage. Neurologic findings are prominent in severe intraventricular hemorrhage cases. The major complications of the germinal matrix-intraventricular hemorrhage in preterm babies are periventricular hemorrhagic infarction, posthemorrhagic ventricular dilatation, periventricular leukomalacia, and cerebellar hemorrhage. It is an important cause of mortality and morbidity. The management of hemodynamics and ventilation of patients, appropriate follow-up, and early diagnosis and treatment can minimize morbidity. Prognosis in intraventricular hemorrhage is related to the severity of bleeding, parenchymal damage, and the presence of seizures and shunt surgery. The main determinant of prognosis is periventricular hemorrhagic infarction and its severity. Moderate-severe intraventricular hemorrhage can cause posthemorrhagic hydrocephalus, cerebral palsy, and mental retardation. Even mild germinal matrix-intraventricular hemorrhage can result in developmental disorders. Long-term problems such as neurodevelopmental disorders and cerebral palsy are as important as short-term problems. Improving the quality of life of these babies should be aimed through appropriate treatment and follow-up. In this review, intraventricular hemorrhage and complications are discussed.

Placental Pathology Findings and the Risk of Intraventricular and Cerebellar Hemorrhage in Preterm Neonates

Placental pathology as a predisposing factor to intraventricular hemorrhage remains a matter of debate, and its contribution to cerebellar hemorrhage development is still largely unexplored. Our study aimed to assess placental and perinatal risk factors for intraventricular and cerebellar hemorrhages in preterm infants. This retrospective cohort study included very low-birth weight infants born at the Gaslini Children's Hospital between January 2012 and October 2016 who underwent brain magnetic resonance with susceptibility-weighted imaging at term-equivalent age and whose placenta was analyzed according to the Amsterdam Placental Workshop Group Consensus Statement. Of the 286 neonates included, 68 (23.8%) had intraventricular hemorrhage (all grades) and 48 (16.8%) had a cerebellar hemorrhage (all grades). After correction for gestational age, chorioamnionitis involving the maternal side of the placenta was found to be an independent risk factor for developing intraventricular hemorrhage, whereas there was no association between maternal and fetal inflammatory response and cerebellar hemorrhage. Among perinatal factors, we found that intraventricular hemorrhage was significantly associated with cerebellar hemorrhage (odds ratio [OR], 8.14), mechanical ventilation within the first 72 h (OR, 2.67), and patent ductus arteriosus requiring treatment (OR, 2.6), whereas cesarean section emerged as a protective factor (OR, 0.26). Inotropic support within 72 h after birth (OR, 5.24) and intraventricular hemorrhage (OR, 6.38) were independent risk factors for cerebellar hemorrhage, whereas higher gestational age was a protective factor (OR, 0.76). Assessing placental pathology may help in understanding mechanisms leading to intraventricular hemorrhage, although its possible role in predicting cerebellar bleeding needs further evaluation.

Preterm brain injury: Germinal matrix-intraventricular hemorrhage and post-hemorrhagic ventricular dilatation

Germinal matrix hemorrhage and intraventricular hemorrhages (GMH-IVH) remain a common and clinically significant problem in preterm infants, particularly extremely preterm infants. A large GMH-IVH is often complicated by posthemorrhagic ventricular dilation (PHVD) or parenchymal hemorrhagic infarction and is associated with an increased risk of adverse neurologic sequelae. The widespread use of cranial ultrasonography since the early 1980s has shown a gradual decrease in the incidence of GMH-IVH and has helped with the identification of antenatal and perinatal risk factors and timing of the lesion. The increased use of magnetic resonance imaging (MRI) has contributed to more detailed visualization of the site and extent of the GMH-IVH. In addition, MRI has contributed to the awareness of associated white matter changes as well as associated cerebellar hemorrhages. Although GMH-IVH and PHVD still cannot be prevented, cerebrospinal fluid drainage initiated in the early stage of PHVD development seems to be associated with a better neurodevelopmental outcome. Further studies are underway to improve treatment strategies for PHVD and to potentially prevent and repair GMH-IVH and PHVD and associated brain injury. This chapter discusses the pathogenesis, incidence, risk factors, and management, including preventive measures, of GHM-IVH and PHVD.

Risk factors associated with intraventricular hemorrhage in extremely premature neonates

: Intraventricular hemorrhage (IVH) is a significant cause of morbidity in extremely premature infants despite many advances in neonatal intensive care. We conducted an institutional retrospective review aimed to correlate risk factors associated with IVH. Clinical variables reported to the Vermont-Oxford Network on less than 30 weeks gestational age infants over a 5-year period were evaluated with Pearson's chi-square and multivariate logistic regression. Of 618 infants born less than 30-week gestational age, 178 (28.8%) experienced IVH. Of those less than 1000 g, 105 (36.5%) of 288 infants experienced IVH. Multivariate analysis revealed that thrombocytopenia [odds ratio (OR) 2.03, 95% confidence interval (CI) 1.30-3.19, P = 0.0020] and cardiopulmonary resuscitation (CPR) ± intubation at delivery (OR 1.84, 95% CI 1.12-3.02, P = 0.0162) were independently associated with IVH. Among infants less than 1000 g, thrombocytopenia (OR 2.09, 95% CI 1.22-3.60, P = 0.0077) and CPR ± intubation at delivery (OR 2.01, 95% CI 1.10-3.68, P = 0.0229) were also significantly associated with IVH. IVH is a complex phenomenon with many contributing risk factors. In our study, infants less than 30-week gestational age and less than 1000 g revealed thrombocytopenia and CPR ± intubation in delivery room were independently associated with IVH. These data should alert clinicians to those neonates most likely to suffer IVH.

Evolution of Factor V Leiden

Factor V Leiden is a procoagulant mutation associated with venous and arterial thrombosis and pregnancy complications. Its high prevalence of 5% in Caucasians suggests that there are evolutionary benefits as well. Carriers are indeed reported to have various advantageous phenotypes related to haemostasis, inflammation and fertility: less acute blood loss; less menstrual blood loss; decreased risk of intracranial haemorrhage; milder phenotypes of haemophilia; higher survival in and lower susceptibility to severe sepsis; higher survival in acute respiratory distress syndrome; less severe diabetic nephropathy and higher fecundity in both men and women. Not all these associations come from high quality adequately powered studies and many have not been confirmed by further research. The evolutionary influence of the alleged associations varies and is difficult to establish, partly due to a shift over time in risk factors of the diseases concerned. For most of the phenotypes possible mechanistic explanations can be provided. The procoagulant phenotype and perhaps also certain pregnancy complications follow from activated protein C (APC) resistance. Elevated APC levels possibly mediate anti-inflammatory effects. Higher sperm counts and more successful embryo implantation seem to play a role in the increased fecundity.

The role of FV 1691G>A, FII 20210G>A mutations and MTHFR 677C>T; 1298A>C and 103G>T FXIII gene polymorphisms in pathogenesis of intraventricular hemorrhage in infants born before 32 weeks of gestation

BACKGROUND

Congenital thrombophilia is associated with an increased intraventricular hemorrhage (IVH) risk among newborns, but it may also play a protective role. The role of genetic polymorphisms involved in the coagulation pathway of IVH pathogenesis is probably a consequence of an increased risk of thrombosis in the fine blood vessels in the germinal matrix region.

MATERIAL AND METHODS

The aim of this study was to evaluate the possible relationship between Factor V (FV) 1691G>A, Factor II (FII) 20210G>A mutations and methylenetetrahydrofolate reductase (MTHFR) 677C>T; 1298A>C and Factor XIII (FXIII) 103G>T gene polymorphisms and the occurrence of IVH in 100 infants born from 24 + 0 to 32 + 0 weeks of gestation, born from singleton pregnancy, before 32 + 0 weeks of gestation, exposed to antenatal steroid therapy, and without congenital abnormalities.

RESULTS

IVH developed 45 (45%) infants, including 15 (33.33%) diagnosed with IVH stage I, 20 (42.22%) with stage II, 8 (17.77%) with stage III, and 3 (6.66%) with stage IV. Analysis showed a prevalence 4.5 times higher of IVH stages II to IV in infants with the genotype CC (OR 4511 (1147-17.75); p = 0.026) of MTHFR 1298A>C gene polymorphism. Our investigation did not confirm any significant prevalence of IVH development in other studied mutations/polymorphisms.

CONCLUSIONS

This study confirmed that the MTHFR 1298A>C polymorphism is associated with the risk of IVH. IVH is a significant problem for preterm infants. In addition to little progress in preventing IVH in preterm babies, substantial research that is focused on understanding the etiology, mechanism, and risk factors for IVH is imperative. In the era of personalized medicine, identification of genetic risk factors creates opportunities to generate preventative strategies.

Evaluation of Factor V Leiden, Prothrombin G20210A, MTHFR C677T and MTHFR A1298C gene polymorphisms in retinopathy of prematurity in a Turkish cohort

BACKGROUND

To assess Factor V Leiden (FVL) (rs6025), Prothrombin G20210A (rs1799963), MTHFR C677T (rs1801133), and MTHFR A1298C (rs1801131) gene mutations as risk factors in the development of retinopathy of prematurity (ROP).

MATERIALS AND METHODS

A total of 105 children were included in this cross-sectional study. Patients were divided into two groups. The study group consisted of 55 infants with a history of ROP and the control group comprised 50 healthy infants with term birth. All subjects were screened for the presence of certain mutations (FVL, Prothrombin G20210A, MTHFR C677T and MTHFR A1298C) by Real-Time PCR at 1 year of age.

RESULTS

The mean gestational age (GA) and birth weight (BW) of the study group were, 28.65 ± 2.85 weeks and 1171 ± 385.74 g, respectively. There were no significant differences of genotype and allele frequency of Prothrombin G20210A, MTHFR A1298C and MTHFR C677T between the study and control groups (p > 0.05). Eight children (14.5 %) had heterozygous and one child (1.8%) had homozygous FVL mutation in the study group. One child (2%) in the control group had heterozygous FVL mutation. There was statistically significant differences of FVL allele and genotype frequencies between the groups (p < 0.05).

CONCLUSIONS

The prevalence of FVL polymorphism (16.3 %) was higher in ROP patients than control subjects in this Turkish cohort. We suggest a possible association of FVL mutation with ROP at the end of the study.

Thromboembolism and anticoagulation management in the preterm infant

The incidence of preterm thromboembolism has been increasing due to advances in diagnostic imaging which allow better detection of thrombi in sick preterm infants. At the same time, improvement in neonatal intensive care unit supportive care has increased the number of surviving and living preterm infants with thromboembolic risk factors. Disruption in the fine balance of hemostasis with potential risk factors, specifically septicemia and indwelling catheters, increase the occurrence of thromboembolic events. Treatment strategies in preterm infants are challenging due to limited data.

Elucidating the role of genomics in neonatal sepsis

Sepsis is a major cause of neonatal morbidity and mortality, especially in vulnerable preterm populations. Immature immune defenses, and environmental and maternal factors contribute to this risk, with as many as a third of very preterm infants experiencing sepsis during their stay in the neonatal intensive care unit (NICU). Epidemiologic and twin studies have suggested that there is a genetic contribution to sepsis predilection. Several investigators have conducted candidate gene association studies on variants of specific interest and potential functional significance in neonatal sepsis. In this review, we describe details of studies that have evaluated genetic susceptibility in neonatal sepsis, and summarize findings from a review of candidate gene association studies.

Genetic variants of the vitamin K dependent coagulation system and intraventricular hemorrhage in preterm infants

Background

Pathogenesis of intraventricular hemorrhage (IVH) in premature infants is multifactorial. Little is known about the impact of genetic variants in the vitamin K-dependent coagulation system on the development of IVH.

Methods

Polymorphisms in the genes encoding vitamin K epoxide reductase complex 1 (VKORC1 -1639G>A) and coagulation factor 7 (F7 -323Ins10) were examined prospectively in 90 preterm infants <32 weeks gestational age with respect to coagulation profile and IVH risk.

Results

F7-323Ins10 was associated with lower factor VII levels, but not with individual IVH risk. In VKORC1-wildtype infants, logistic regression analysis revealed a higher IVH risk compared to carriers of the -1639A allele. Levels of the vitamin K-dependent coagulation parameters assessed in the first hour after birth did not differ between VKORC1-wildtype infants and those carrying -1639A alleles.

Conclusions

Our data support the assumption that genetic variants in the vitamin K-dependent coagulation system influence the coagulation profile and the IVH risk in preterm infants. Further studies focussing on short-term changes in vitamin K-kinetics and the coagulation profile during the first days of life are required to further understand a possible link between development of IVH and genetic variants affecting the vitamin K-metabolism.

Spontaneous intestinal perforation and multiple thrombotic events in a neonate with thrombophilia

Spontaneous intestinal perforation (SIP), a rare complication in neonates, was diagnosed in a preterm newborn. After surgery, small bowel histology showed acute ischemic changes and one area of perforation. Fibrin thrombus in the submucosal capillary vessels suggested a thrombotic mechanism in the pathogenesis. Subsequently, two severe asynchronous thrombotic events developed: cerebral sinovenous thrombosis and renal vein and inferior vena cava thrombosis. The neonate presented with hypercoagulability and factor V Leiden heterozygosity. This is the first association of SIP with inherited thrombophilia and thrombotic events in a neonate, suggesting hypercoagulability as a new research focus for pathogenesis of this enigmatic disease.

Bi-directional activation of inflammation and coagulation in septic neonates

Neonatal sepsis is frequently accompanied by significant and sometimes life-threatening coagulopathy. More complete understanding is needed of the molecular and cellular mechanisms underlying the interaction of the inflammatory and hemostatic systems. Such information may help focus future studies toward novel ways to improve the outcome of neonates who develop septic coagulopathy.

Lack of Association Between Factor V Leiden and Sepsis

Some studies evaluated the association of factor V Leiden (FVL) with sepsis risk and mortality risk. However, the results were conflicting. Thus, we performed a meta-analysis to address the association between FVL and sepsis. PubMed and EMBASE databases were searched to find relevant studies. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were estimated using random effects model. Five case–control studies and 3 cohort studies were included. Overall, no significant association between FVL and sepsis risk was observed (OR = 0.93; 95% CI 0.74-1.15; P = .49). In addition, there was no significant association between FVL and sepsis-related mortality (OR = 1.17; 95% CI 0.73-1.88; P = .52). In the subgroup analysis, no increased sepsis risk and mortality risk were found in caucasian population. This meta-analysis suggested that FVL was not a risk factor for sepsis and sepsis mortality.

Progress in understanding the genetics of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is the most common chronic lung disease in infants. Its treatment imposes considerable healthcare burden and costs in the perinatal and early childhood period and patients are usually left with lifelong deficits in lung function. Evidence exists for different pathophysiologic pathways that can promote the structural changes that characterize BPD, including the impairment in alveolarization; however, there is increasing interest regarding heritable factors that may predispose very low birth weight infants to BPD. Our review focuses on recent publications that have investigated genetic factors that may potentially contribute to such reported heritability. These publications point us toward some possible genomic candidates for further study, but certainly do not identify any particular gene or gene pathway that would be inferred to be contributing substantially to the underlying etiology of BPD.

Prediction of sepsis-related outcomes in neonates through systematic genotyping of polymorphisms in genes for innate immunity and inflammation: a narrative review and critical perspective

CONTEXT AND OBJECTIVE

Neonatal sepsis is associated with premature birth and maternal infection. Large-scale studies seek to define markers that identify neonates at risk of developing sepsis. Here, we examine whether the scientific evidence supports systematic use of polymorphism genotyping in cytokine and innate immunity genes, to identify neonates at increased risk of sepsis.

DESIGN AND SETTING

Narrative literature review conducted at Fernandes Figueira Institute, Brazil.

METHODS

The literature was searched in PubMed, Embase (Excerpta Medica Database), Lilacs (Literatura Latino-Americana e do Caribe em Ciências da Saúde), SciELO (Scientific Electronic Library Online) and Cochrane Library. From > 400,000 references, 548 were retrieved based on inclusion/exclusion criteria; 22 were selected for detailed analysis after quality assessment.

RESULTS

The studies retrieved addressed the impact of gene polymorphisms relating to immune mechanisms (most often TNF-a, LT-a, IL-6, IL-1β, IL-1ra, L-selectin, CD14 and MBL) or inflammatory mechanisms (ACE and angiotensin II receptors; secretory PLA2; and hemostatic factors). Despite initial reports suggesting positive associations between specific polymorphisms and increased risk of sepsis, the accumulated evidence has not confirmed that any of them have predictive power to justify systematic genotyping.

CONCLUSIONS

Sepsis prediction through systematic genotyping needs to be reevaluated, based on studies that demonstrate the functional impact of gene polymorphisms and epidemiological differences among ethnically distinct populations.

Atypical timing and presentation of periventricular haemorrhagic infarction in preterm infants: the role of thrombophilia

AIM

Periventricular haemorrhagic infarction (PVHI) is a complication of preterm birth associated with cardiorespiratory instability. To date, the role of thrombophilia as a possible additional risk factor in infants with atypical timing and presentation of PVHI has not been investigated.

METHOD

This was a retrospective cohort study of preterm infants who developed PVHI with an atypical timing and presentation either of antenatal onset or late in the postnatal course in the absence of a preceding sudden deterioration of their clinical condition. In infants with atypical PVHI mutation analysis of the factor V Leiden (G1691A), prothrombin (G20210A) gene, and C677T and A1298C polymorphisms in the MTHFR gene was performed, and plasma lipoprotein(a) and homocysteine levels were measured.

RESULTS

Sixty-two preterm infants who presented with a PVHI were studied. Seventeen had an atypical presentation (seven males, 10 females; median birthweight 1170g [range 580-1990g]; median gestational age 30.6wks [range 28.7-33.7wks]). The typical PVHI group comprised 28 males and 17 females (median birthweight 1200g [range 670-2210g]; median gestational age 29.6wks [range 25.3-33.6wks]). Among the 17 infants with atypical presentation, the factor V Leiden mutation was found in seven infants (41%) as well as in the mothers of six of these seven infants; in one infant this was concomitant with a prothrombin gene mutation. A polymorphism in the MTHFR gene was also present in these infants. In two infants with an atypical presentation who were tested for this, a mutation in the COL4A1 gene was found (reported previously). All but two of the infants with an atypical presentation developed spastic unilateral cerebral palsy.

INTERPRETATION

An atypical presentation of PVHI in preterm infants tends to occur more often in the presence of thrombophilia. Testing of thrombophilia, especially factor V Leiden and prothrombin gene mutation, is recommended in these infants.

Preterm infant with a catastrophic hemorrhagic-thromboembolic incident

Thrombotic disease of the newborn is uncommon but usually associated with serious morbidity and mortality. Although the operating mechanisms of coagulation and fibrinolysis are the same in all age groups, plasma concentrations of the two systems' components are significantly different in neonates compared to children and adults. This places neonates at greater risk for thrombosis that may rise considerably if a predisposing factor is present or a genetic or medical condition predisposing to thrombosis coexists. While marginal, the possibility of abnormal bleeding secondary to congenital prothrombotic disorders has been described. A significant association between thromboembolic/hemorrhagic disease in newborns and each of factor V(Leiden) and prothrombin G20210A mutations has been reported. Although not a frequent occurrence in adults and children, congenital 'multigenic' thrombophilia is well known. However, the combined heterozygote state of both mutations is perhaps underreported in preterm infants. We present a severely intrauterine growth-restricted preterm baby born to consanguineous parents. He had stroke as part of a generalized bleeding-thromboembolic incident caused by combined heterozygote mutation of factor V(Leiden) and prothrombin G20210A, each of which was then found in a heterozygote form in each of the 2 parents.

Replication of genetic associations in the inflammation, complement, and coagulation pathways with intraventricular hemorrhage in LBW preterm neonates

Intraventricular hemorrhage (IVH) is a significant morbidity seen in very LBW infants. Genes related to the inflammation, infection, complement, or coagulation pathways have been implicated as risk factors for IVH. We examined 10 candidate genes for associations with IVH in 271 preterm infants (64 with IVH grades I-IV and 207 without IVH) weighing <1500 g. The heterozygous genotype OR = 8.1, CI = 2.5-26.0, p = 4 × 10(-4)) and the A allele (OR = 7.3, CI = 2.4-22.5, p = 1 × 10(-4)) of the coagulation factor V (FV) Leiden mutation (rs6025) were associated with an increased risk of developing IVH grade I or II but not grade III or IV after correction for multiple testing with Bonferroni. Lack of association in the severe grades of IVH may be a result of lack of power to detect an effect given the small sample size (n = 8). However, this result is consistent with previous research that demonstrates that the heterozygous genotype of the FV mutation is associated with increased risk for the development of IVH but a decreased risk for the progression or extension to more severe grades of IVH.

Targeting inflammation to prevent bronchopulmonary dysplasia: can new insights be translated into therapies?

Bronchopulmonary dysplasia (BPD) frequently complicates preterm birth and leads to significant long-term morbidity. Unfortunately, few therapies are known to effectively prevent or treat BPD. Ongoing research has been focusing on potential therapies to limit inflammation in the preterm lung. In this review we highlight recent bench and clinical research aimed at understanding the role of inflammation in the pathogenesis of BPD. We also critically assess currently used therapies and promising developments in the field.

The role of plasminogen activator inhibitor-1 and angiotensin-converting enzyme gene polymorphisms in bronchopulmonary dysplasia

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a multifactorial disease of preterm infants that is characterized by airway injury, inflammation, and parencymal remodeling. Activation of the coagulation cascade leads to intraalveolar fibrin deposition in many inflammatory pulmonary disorders. Increased fibrin formation or decreased fibrinolysis may cause extravascular fibrin deposition. Extravascular fibrin deposits in septae and alveoli due to the altered fibrin turnover are the pathological hallmarks of BPD, which strongly indicate the importance of the imbalance in the competing activities of coagulation and fibrinolysis.

OBJECTIVE

We investigated the predictive value of variations in plasminogen activator inhibitor-1 (PAI-1) and angiotensin-converting enzyme (ACE) genes as molecular determinants for BPD in neonates.

METHODS

The study group comprised 98 preterm infants with BPD and a control group including 94 preterm infants without BPD. Restriction fragment size analyses were performed by visualizing digested polymerase chain reaction products for ACE and PAI-1 genotypes.

RESULTS

No significant associations were found between ACE, PAI-1 gene polymorphisms, and BPD phenotype in our population.

CONCLUSIONS

The two gene polymorphisms (PAI-1 and ACE) had no role in the development of BPD in our study. Further studies with other genes are required for the identification of molecular predisposing factors for BPD that may help in the development of new treatments.

An age-related decrease in factor V Leiden frequency among Polish subjects

Factor V Leiden (G1691A FV mutation) is a widely acknowledged risk factor of deep vein thrombosis, including pulmonary embolism as the most serious complication. However, its high prevalence of ~5%in the Caucasian population might be related to an unknown evolutionary advantage. It might exert a beneficial effect on the carrier, e.g. protecting women from excessive bleeding during labour or allowing increased survival in severe sepsis or with other inflammatory diseases. The aim of our study was to verify or contradict the hypothesis of a favourable association between the A allele (A1691) and longevity in the Polish population. For this purpose, the G1691A mutation was analyzed by PCR-RFLP in 1016 Poles: 400 neonates (187 female and 312 male), 184 healthy adults (129 female and 55 male), and 432 long-lived individuals (age ≥95 years: 343 women and 89 men). Frequencies of G1691A carriers and the A1691 allele in long-lived individuals (0.2% and 0.1%, respectively) were significantly lower than in neonates (4.2% and 2.2%, respectively) and adults (3.3% and 1.6%). The frequency of the G1691A factor V Leiden mutation decreased with age, which indicates a shorter survival time among A1691 allele carriers in the Polish population.

Genetics of bronchopulmonary dysplasia in the age of genomics

PURPOSE OF REVIEW

According to recent evidence, susceptibility to bronchopulmonary dysplasia (BPD) in preterm infants is predominantly inherited. The purpose of this review is to discuss current published genetic association studies in light of the accumulated knowledge in genomics.

RECENT FINDINGS

Major advances in the development of next-generation genotyping and sequencing platforms, statistical methodologies, inventories of functional outcome of some common genetic polymorphisms and large-scale cataloguing of genetic variability among many of the world's ethnic populations have greatly facilitated the study of polygenic conditions. For BPD, genetic-association studies have primarily focused on components of innate (e.g. first-line) immune and antioxidant defences, mechanisms of vascular and lung remodelling, and surfactant proteins. However, studies have been limited in sample size and therefore fraught with a high probability of false-positive and false-negative associations. Nonetheless, candidate gene associations have indicated some novel biological pathways and provide a conceptual framework for the design of larger, collaborative population-based studies.

SUMMARY

Although studies to date have not been able to identify reproducible genetic risk markers for BPD, they have directed us towards new, promising research avenues.

Lack of association between FXIII-Val34Leu, FVII-323 del/ins, and transforming growth factor beta1 (915G/T) gene polymorphisms and bronchopulmonary dysplasia: a single-center study

Bronchopulmonary dysplasia (BPD) is a multifactorial disease of preterm infants that is characterized by airway injury, inflammation, and parenchymal remodeling. Extravascular fibrin deposits in septae and alveoli due to the altered fibrin turnover are the pathological hallmarks of BPD that strongly indicates the importance of the imbalance in the competing activities of coagulation and fibrinolysis. Activation of the coagulation cascade leads to intraalveolar fibrin deposition in many inflammatory pulmonary disorders. Increased fibrin formation or decreased fibrinolysis may cause extravascular fibrin deposition. We evaluated the association between FXIII-Val34Leu, FVII-323 del/ins, and transforming growth factor beta1 (TGF-beta(1)) (915G/T) gene polymorphisms in patients with BPD. The study group consisted of 98 preterm infants with BPD. Ninety-four of the 192 preterm neonates were without BPD and sampled for the control group. Restriction fragment size analyses were performed by examining digested PCR products for FXIII-Val34Leu, FVII-323 del/ins, and TGF-beta(1) (915G/C) genotypes. No significant associations were found between FXIII-Val34Leu, FVII-323 del/ins, TGF-beta(1) (915G/C) gene polymorphisms and BPD phenotype in our population. Further studies with other genes are required for the identification of molecular predisposing factors for BPD that may help in the development of new treatments and hence might allow for targeting of this treatment to a "high-risk" subgroup, reducing unnecessary exposure to potentially harmful therapies.

The role of genomics in the neonatal ICU

Results of both the Human Genome and International HapMap Projects have provided the technology and resources necessary to enable fundamental advances through the study of DNA sequence variation in almost all fields of medicine, including neonatology. Genome-wide association studies are now practical, and the first of these studies are appearing in the literature. This article provides the reader with an overview of the issues in technology and study design relating to genome-wide association studies and summarizes the current state of association studies in neonatal ICU populations with a brief review of the relevant literature. Future recommendations for genomic association studies in neonatal ICU populations are also provided.

The hemostatic balance revisited through the lessons of mankind evolution

Under physiologic conditions, a hemostatic balance is achieved through the effects of natural procoagulant and anticoagulant factors which, in equilibrium with each other, provide hemostasis at the sites of vascular injury. Abnormalities of these hemostasis factors can result in a tendency toward hemorrhagic or thrombotic events. In this review the influence of inherited prothrombotic risk factors--especially the more frequent factor V Leiden and prothrombin gene mutations--on normal and abnormal hemostasis is analyzed from an evolutionary point of view. The effect of inherited bleeding disorders on the development of thrombotic or atherosclerotic processes is also discussed.

Current approaches for risk stratification of infectious complications in pediatric oncology

Infections are serious complications of cytoreductive therapy in pediatric cancer patients presenting with febrile neutropenia. It is standard of care to initiate empirical intravenous broad-spectrum antibiotics until the fever and neutropenia resolve. However, it might be effective and safe to allow for early hospital discharge in certain subgroups of patients. Two strategies for risk stratification of pediatric cancer patients with regard to infectious complications are discussed in this review: (1) clinical risk parameters and laboratory measures to assist therapeutic management at presentation with fever in neutropenia, and (2) investigations of individual genetic susceptibility factors to tailor potential prophylactic approaches. Given the data available from a significant number of small studies, a large prospective non-inferiority trial is essential to assess low-risk clinical factors and additional laboratory or genetic markers for their predictive value.

Impact of common genetic variation on neonatal disease and outcome

The main aim of identifying gene-environment interactions is to provide insight into mechanisms of disease development and to identify patients with an inherent vulnerability to certain conditions. This in turn may allow patients to be targeted with individualised treatment based on the knowledge of their inborn susceptibility to specific conditions. This review describes the possible effects of common genetic variation on outcome in various conditions affecting the neonate. It focuses predominantly on studies of positive association rather than non-association to illustrate this potential influence and to highlight the potential for further study and intervention. The shortcomings of published association studies and the place of such studies in future research are also discussed.

Genetic association studies in VLBW infants exemplifying susceptibility to sepsis--recent findings and implications for future research

CONTEXT

In recent years, tremendous effort has been carried out to study the genetic basis of susceptibility to development, progression and severity of complex diseases and response to therapy. The ultimate goal of these investigations is to find new tools for prevention and treatment of these complex diseases, such as sepsis in very-low-birth-weight (VLBW) infants. VLBW cohorts have a restricted clinical risk profile for the development of sepsis including immaturity of immune functions and antenatal/perinatal risk factors but also a significant event rate of sepsis within a short period of observational time. Therefore, prospective VLBW cohorts are advantageous for the investigation of candidate genetic risk factors of sepsis compared to adult cohorts. Furthermore, environmental factors are much better documented and highly controlled for VLBW infants in a standardized NICU setting compared to adult cohorts which are influenced by a variety of environmental risk factors, e.g. habits and comorbidities.

OBJECTIVE

The aim of this review is to discuss the value and limitations of genetic association studies in VLBW infant cohorts exemplifying recent findings for genetic susceptibility to neonatal sepsis.

DATA SOURCE

Published Medline articles reporting on studies of associations between genetic polymorphisms, neonatal sepsis and septic shock in VLBW infants.

CONCLUSIONS

Up-to-date, the classical approach to investigate the genetic component of susceptibility to sepsis in VLBW infants by means of twin and concordance studies has not been implemented yet. Regarding the interpretation of data from current genetic association studies, one should be aware of significant differences in cohort size, study design and definition of cases, controls and clinical end points. Furthermore, the contribution of genetic variants to susceptibility to sepsis may be specifically influenced by the immaturity of the immune response in VLBW infants, the selectivity of responsiveness to certain pathogens and the genotopyic/phenotypic variability of pathogens. We provide implications for the conduct and evaluation of future association studies with particular reference to methodological quality standards.

Genes and environment in common neonatal lung disease

Respiratory distress syndrome (RDS) and bronchopulmonary dysplasia (BPD) are common, serious lung diseases in preterm infants. Polymorphism of the genes involved in basic lung function and alveolar stability, lung differentiation and pulmonary host defense may influence the risk. Natural selection has refined the genes responsible for cardiopulmonary adaptation and resistance against pneumonia in term and near-term infants. Before the era of antibiotics, however, virtually all very preterm infants died of asphyxia, respiratory failure or infections. Today, the degree of prematurity plays a dominant role in susceptibility to serious lung disease. In addition, genetic polymorphism and constitution modulate the risk of RDS and BPD that have different, partly overlapping predisposition. According to twin studies, the genetic impact on the risk of RDS and BPD among preterm and very preterm infants is 35-65%. Individual disease genes generally have low penetrance. Large-scale genetic studies are required as part of neonatal and perinatal research in order to learn about the risk factors and to investigate pharmacogenetics. The aim in the future is to individualize therapies.