Heinrich Vielhaber

Infant methylenetetrahydrofolate reductase 677TT genotype is a risk factor for congenital heart disease

OBJECTIVE Recently, an association between the homozygous C677T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene in infants with congenital neural tube defects or congenital oral clefts has been shown. However, no data are available so far with respect to the MTHFR 677TT genotype in children with underlying structural congenital heart disease (CHD). METHODS We investigated the MTHFR genotype in 114 Caucasian CHD patients aged newborn to 16 years (median 0.6 years; 53% male) and in 228 age- and sex-matched healthy controls. RESULTS In childhood patients with CHD the homozygous MTHFR 677TT genotype was found in 21 out of 114 subjects (18.4%) compared with 21 out of 228 controls (9.2%; odds ratio (OR) 2.2, 95%-confidence interval (CI) 1.2-4.3; P=0.027). In patients with pulmonary valve stenosis, hypoplastic left heart syndrome, coarctation of the aorta, aortic valve stenosis or subaortic stenosis the frequency of the TT genotype varied between 38 and 67% with corresponding ORs from 6.1 (CI, 1.4-27.5; P=0.034) to 20.4 (CI, 1.8-235.0; P=0.025), whereas in other structural CHD the frequency of this genotype was not significantly different from the controls. CONCLUSIONS With the present study we can show for the first time that the embryonal MTHFR 677TT genotype is significantly associated with the development of structural congenital heart malformations during early pregnancy. It remains to be clarified, whether this genotype is at least a risk marker or a risk factor for structural congenital heart malformations.

Factor V Leiden, protein C, and lipoprotein (a) in catheter-related thrombosis in childhood: A prospective study

OBJECTIVE To determine the association between catheter-related thromboses and hereditary causes of thrombophilia, including the factor V Leiden mutation, deficiencies of protein C or protein S, or increased lipoprotein (a). STUDY DESIGN To evaluate the incidence of genetic risk factors for familial thrombophilia in catheter-related thrombosis, 163 consecutively admitted infants and children (cardiac disease and catheter placement [C] n = 140; Broviac catheter [B] n = 23) were prospectively investigated. In addition, an age-matched, healthy control group undergoing elective surgery (S: n = 155) was investigated. RESULTS Heterozygous factor V Leiden mutation was diagnosed in 20 of the 318 study subjects (C: n = 5; B: n = 4; S: n = 11), homozygous factor V Leiden mutation was found in two subjects (C: n = 1; S: n = 1), protein C deficiency type I was diagnosed in nine subjects (C: n = 4; B: n = 1; S: n = 4), and five subjects showed increased lipoprotein (a) (C: n = 3; S: n = 2). The frequency of thrombosis (C: n = 13; B: n = 5) in patients with familial thrombophilia was significantly higher (p < 0.0001; chi square: 27.79) in the catheter groups (15 of 17 subjects) than in control subjects after minor elective surgery (none of 18). Fifteen of the 18 infants with thrombosis had congenital thrombophilia; two children with congenital thrombophilia did not have documented thrombosis, and three infants with vascular occlusion had no inherited predisposition to thrombophilia. CONCLUSIONS Genetic risk factors for familial thrombophilia play an important role in the manifestation of catheter-related thromboembolism in children.

Factor V Leiden and genetic defects of thrombophilia in childhood porencephaly

AIMS To determine to what extent the Arg506 to Gln point mutation in the factor V gene and further genetic factors of thrombophilia affect the risk of porencephaly in neonates and infants. METHODS The Arg506 to Gln mutation, factor V, protein C, protein S, antithrombin, antiphospholipid antibodies and lipoprotein (a) (Lp(a)) were retrospectively measured in neonates and children with porencephaly (n=24). RESULTS Genetic risk factors for thrombophilia were diagnosed in 16 of these 24 patients: heterozygous factor V Leiden (n=3); protein C deficiency type I (n=6); increased Lp (a) (n=3); and protein S type I deficiency (n=1). Three of the 16 infants had two genetic risk factors of thrombophilia: factor V Leiden mutation combined with increased familial Lp (a) was found in two, and factor V Leiden mutation with protein S deficiency type I in one. CONCLUSIONS The findings indicate that deficiencies in the protein C anticoagulant pathway have an important role in the aetiology of congenital porencephaly.

The plasminogen activator inhibitor (PAI)‐1 promoter 4G/4G genotype is not associated with ischemic stroke in a population of German children

Abstract: Objectives: To investigate the relationship between an insertion/deletion (4G/5G) polymorphism of the plasminogen activator inhibitor (PAI)‐1 gene and childhood patients with a past history of ischemic stroke. Methods: The PAI‐1 4G/4G genotype and the coinheritance with lipoprotein (Lp) (a) levels, the factor V (FV) G1691A mutation, the prothrombin (PT) G20210A variant, and the methylenetetrahydrofolate reductase (MTHFR) T677T genotype were studied in 198 Caucasian children with stroke and 951 controls (same age, sex and ethnical distribution). In a randomly selected subgroup of patients/controls (n=60) PAI‐1 activities have been investigated. Results: The distribution of the 4G/5G genotypes was no different in childhood stroke patients and controls, with a 4G allele frequency of 55.8% in patients compared with 53.8% in control subjects (P=0.49). The 4G/4G genotype compared with the remaining genotypes was present in 43 cases and 167 (17.6% vs. 21.7%; OR/CI: 1.30/0.89–1.98; P=0.3). PAI‐1 activity was significantly elevated (P<0.001) in the patient group. Conclusions: Data presented here suggest that the 4G/4G genotype is not a major risk factor in the aetiology of childhood ischemic stroke.

Coagulation and fibrinolysis in children, adolescents, and young adults with inflammatory bowel disease.

BACKGROUND Patients with Crohns disease and ulcerative colitis have an increased risk of thromboembolic events. METHODS Data were collected from 24 patients aged 4.5 to 23 years who had inflammatory bowel disease. Platelet count, antithrombin, fibrinogen, prothrombin fragment F1+2, soluble thrombomodulin, tissue plasminogen activator, D-dimer, and plasminogen activator inhibitor-1 antigen were investigated. In addition the response to activated protein C, the factor V R506Q mutation, protein C, free protein S antigen, and lipoprotein (a) were analyzed. These data were compared with medical treatment, duration, and disease activity, estimated with the Pediatric Crohns Disease Activity Index or the Clinical Colitis Activity Index. RESULTS Forty-five percent of our patients showed an increase in fibrinogen, 29% in prothrombin fragment F1+2, and 20% in platelet count, plasminogen activator inhibitor- antigen, and soluble thrombomodulin. Thrombomodulin was higher in active disease than in inactive disease and in Crohns disease than in ulcerative colitis. Fibrinogen was also higher with Crohns disease and tended to be higher in active disease than in ulcerative colitis and inactive disease. Plasminogen activator inhibitor-1 antigen was significantly higher in patients with Crohns disease than in those with ulcerative colitis and was higher in the patient group treated with steroids. CONCLUSION As has been shown in adults, young patients with active and inactive inflammatory bowel disease were found to have abnormal coagulation and fibrinolysis. The relevance as a thromboembolic risk factor is discussed.

APC resistance in neonates and infants: Adjustment of the aPTT - based method

Resistance to activated protein C (APCR) has emerged as the most important hereditary cause of venous thromboembolism. Using an aPTT-based method together with DNA technique we investigated 120 healthy neonates and infants < 12 months of age and 24 infants with septicaemia for the presence of this mutation. In addition, data of 11 neonates with vascular occlusion, heterozygous (+/-) for the Arg 506 Gln mutation were included. Results of an aPTT-based method (clotting time using the APC/CaCl2 solution obtained in an undiluted, 1:5 and 1:11 dilution with factor V deficient plasma divided by clotting time with CaCl2 in the same plasma dilution) are shown: Whereas 7 (5.5%) out of 120 healthy neonates were (+/-) carriers for the factor V Arg 506 Gln mutation, concordance with the aPTT-based method (cut-off defined as ratio < 2) was found only when using the 1:11 plasma dilution. Six (four) out of 24 infants with sepsis, not carrying the factor V mutation, would have been classified as APC resistant when using the 1:1 (1:5) plasma dilution. Four (two) out of 18 patients, (+/-) for the Arg 506 Gln mutation showed APC ratios > 2 in the 1:1(1:5) plasma dilution.

Interaction of Fibrinolysis and Prothrombotic Risk Factors in Neonates, Infants and Children With and Without Thromboembolism and Underlying Cardiac Disease-A Prospective Study

UNLABELLED To evaluate the role of plasminogen activator inhibitor-1 (PAI-1) and tissue-type plasminogen activator (t-PA) in children with an estimated risk of vascular occlusion reported to range from 7% to 16%, we conducted a prospective study in infants and children with underlying cardiac disease. One hundred and twenty-five children (neonate - 16 years) were investigated. In 9 infants out of the 125 children vascular occlusion occurred, closely related to cardiac catheterisation and arterial or venous lines during major cardiac surgery. Six of the nine neonates and infants with (n=6) and without (n=3) prothrombotic risk factors showed evidence of a basically impaired fibrinolytic system. Five of the nine infants showed increased PAI-1 clearly correlated to the 4G/4G genotype of the plasminogen activator-1 promoter polymorphism along with elevated t-PA concentration before the first diagnostic cardiac catheterisation was performed. One infant presented with increased t-PA concentration only. Five of the six children with reduced fibrinolytic capacity had further prothrombotic risk factors. CONCLUSION Data of this study indicate that neonates and infants with underlying cardiac disease and basically increased PAI-1 due to the 4G/4G variant of the PAI-1 promoter polymorphism along with elevated t-PA levels in combination with further prothrombotic risk factors are at high risk of developing early thromboembolism during cardiac catheterisation.

Thromboembolism and resistance to activated protein C in children with underlying cardiac disease

OBJECTIVES In the majority of cases, resistance to activated protein C is caused by the point mutation Arg506 to Gln in the factor V gene and has emerged as the most important hereditary cause of thromboembolism. METHODS To determine to what extent resistance to activated protein C was present in children with thromboembolism and underlying cardiac disease, its occurrence was retrospectively investigated. By using a method based on activated partial thromboplastin time, with DNA technique derived from the polymerase chain reaction, we investigated nine children with underlying cardiac disease in whom thromboembolism had previously occurred. RESULTS Heterozygous Arg506-to-Gln mutation in the factor V gene was diagnosed in five of the nine children investigated. In addition, protein C type I deficiency w as found in three patients, and two of the nine children showed increased lipoprotein (a) plasma values. Risk factors were present in all children with symptoms. CONCLUSIONS These data indicate that deficiencies in the protein C anticoagulant pathway are likely to play an important role in the early manifestation of thromboembolism in children with underlying cardiac disease.

REGULAR ARTICLEInteraction of Fibrinolysis and Prothrombotic Risk Factors in Neonates, Infants and Children With and Without Thromboembolism and Underlying Cardiac Disease: A Prospective Study

UNLABELLED To evaluate the role of plasminogen activator inhibitor-1 (PAI-1) and tissue-type plasminogen activator (t-PA) in children with an estimated risk of vascular occlusion reported to range from 7% to 16%, we conducted a prospective study in infants and children with underlying cardiac disease. One hundred and twenty-five children (neonate - 16 years) were investigated. In 9 infants out of the 125 children vascular occlusion occurred, closely related to cardiac catheterisation and arterial or venous lines during major cardiac surgery. Six of the nine neonates and infants with (n=6) and without (n=3) prothrombotic risk factors showed evidence of a basically impaired fibrinolytic system. Five of the nine infants showed increased PAI-1 clearly correlated to the 4G/4G genotype of the plasminogen activator-1 promoter polymorphism along with elevated t-PA concentration before the first diagnostic cardiac catheterisation was performed. One infant presented with increased t-PA concentration only. Five of the six children with reduced fibrinolytic capacity had further prothrombotic risk factors. CONCLUSION Data of this study indicate that neonates and infants with underlying cardiac disease and basically increased PAI-1 due to the 4G/4G variant of the PAI-1 promoter polymorphism along with elevated t-PA levels in combination with further prothrombotic risk factors are at high risk of developing early thromboembolism during cardiac catheterisation.

Flush heparin during cardiac catheterisation prevents long-term coagulation activation in children without APC-resistance-preliminary results

This study was designed to prospectively evaluate haemostatic activation in 75 children undergoing cardiac catheterisation with intermittent flush heparin (10 IU/ml saline) and to relate these data to clinical findings and inherited risk factors for thrombophilia. In addition to flush heparin in infants < 6 months of age in whom additional arterial catheterisation was performed (n = 5) or patients with thrombophilia, heparin (300-400 IU/kg/d) was administered for a further 24 h. APTT was prolonged and anti Xa activity was significantly increased at the end of catheterisation and returned to normal 24 hours later. Whereas thrombin generation (F1 + 2) showed a significant coagulation activation at the end of catheterisation, no concomitant fibrinolytic activation (D-Dimer) was observed. Four children showed resistance to APC: one of them in whom stroke had occurred before and one additional child heterozygous for APCR received further prophylactic heparin. Two neonates with APCR and flush heparin only suffered from thrombosis after catheterisation. No further thrombotic events occurred. This study indicates that low-dose flush heparin during catheterisation may prevent long-term haemostatic activation in children without thrombophilia. Whether further heparin after cardiac catheterisation in children with APCR prevents vascular insults requires a more intensive study.