Childhood stroke associated with familial protein S deficiency

The roles of anatomic factors, thrombophilia, and antithrombotic therapies in childhood-onset arterial ischemic stroke

Childhood-onset arterial ischemic stroke (AIS) is a rare disorder with high risks of both recurrent stroke and life-long neurological morbidity. Anatomic risk factors for primary and/or recurrent AIS include a venous thrombotic source for paradoxical embolism via a patent foramen ovale, primary cardioembolism, extracranial dissection, and intracranial arteriopathies, among others. Genetic and acquired thrombophilias are common, some of which have been shown to have prognostic influence on risk of recurrent AIS. While knowledge of childhood AIS risk factors has grown considerably in recent years, an evidence-based understanding of optimal antithrombotic therapy strategies has not yet been attained. Consensus-based guidelines have been developed, but future research must emphasize identification of additional prognostic factors and the initiation of cooperative randomized controlled clinical trials.

Prothrombotic risk factors in the evaluation and management of perinatal stroke

The ischemia in children affected by perinatal stroke has long been thought to be driven by nonhematologic maternal and perinatal events. New information from clinical studies, however, tells us that plasma-phase risk factors, such as factor V Leiden, elevated lipoprotein (a), and mutations in MTHFR, may be important in the pathogenesis of perinatal stroke, if not always in the risk of recurrence. With regard to stroke recurrence, this risk is only about 2% according to the largest follow-up study to date, and certainly less than 5%. Nonetheless, when strokes do recur, they tend to be associated with the presence of plasma-phase risk factors in the affected child, suggesting that a small percentage of children with a first perinatal stroke may benefit from anticoagulation therapy, both to prevent stroke recurrence as well as occurence of a second, non-CNS thrombotic event. Counselling of parents with regard to subsequent pregnancies should always include medical management of systemic maternal disorders, such as diabetes, persistently elevated antiphospholipid antibodies, and inherited maternal hypercoagulability states.

Coagulopathies and arterial stroke

Although hypercoagulable states are most often associated with venous thrombosis, arterial thromboses are reported in protein S, protein C, and antithrombin III deficiencies, factor V Leiden and prothrombin gene mutations, hyperhomocysteinemia, dysfibrinogenemia, plasminogen deficiency, sickle cell disease, and antiphospholipid antibody syndrome.

Arterial ischemic stroke in childhood: the role of plasma-phase risk factors

The role of plasma-phase risk factors for stroke in the pediatric age group is presently unclear due to the lack of sufficiently large prospective studies, and due to the fact that these risk factors do not apply uniformly to newborns, children with sickle cell disease, and older children. Available evidence indicates that factor V Leiden, prothrombin 20210A, and lipoprotein (a) are all important in the pathogenesis of arterial ischemic stroke in older children, but the role of other plasma-phase risk factors remains uncertain. The contribution of these risk factors to newborn stroke and the stroke of children with sickle cell disease is similarly unclear, likely because the ischemia in affected children is predominantly due to nonhematologic perinatal events and erythrocyte adhesion to endothelium with obstruction of flow in the cerebral microcirculation, respectively. Evaluation of childhood stroke should, in our view, always be performed from the standpoint of the presenting clinical symptoms, diagnostic imaging, and determination of plasma-phase risk factors. Therapeutic anticoagulation and use of antiplatelet agents at present focus on the older child.

Factor V Leiden and antiphospholipid antibodies are significant risk factors for ischemic stroke in children

BACKGROUND AND PURPOSE

The association between ischemic childhood stroke and thrombophilia has been debated. We studied the prevalence of thrombophilia risk factors in 65 unrelated children with ischemic stroke compared with 145 control subjects.

METHODS

Patients and control subjects were tested for antithrombin protein C and protein S deficiencies, the presence of antiphospholipid antibodies (APLA), factor V Leiden (FVL), G20210A polymorphism of factor II gene (FII G20210A), and C677T polymorphism of 5,10-methylenetetrahydrofolate reductase gene (C677T MTHFR).

RESULTS

Of 65 children, 7 had a stroke in the neonatal/perinatal period and therefore were analyzed separately. Thirty-one of the remaining 58 patients with pediatric stroke (53.4%) were found to have at least 1 thrombophilia marker compared with only 25.5% of control subjects. None of the patients or control subjects had protein S or antithrombin III deficiency. The prevalence of protein C deficiency was higher among pediatric stroke patients than among control subjects, but the difference was not statistically significant (OR=7, 95% CI 0.75 to 65.1). Heterozygous FII G20210A and homozygous MTHFR 677T were not associated with an increased risk for stroke (OR=1.29, 95% CI 0.2 to 8.2; and OR=1.06, 95% CI 0.4 to 2.7, respectively). In contrast, the presence of APLA was associated with a >6-fold risk of stroke (OR=6. 08, 95% CI 1.5 to 24.3), and the heterozygosity for FVL increased the risk of stroke by almost 5-fold (OR=4.82, 95% CI 1.4 to 16.5). Five patients with pediatric stroke had a combination of > or =2 thrombophilia markers, whereas none of the control subjects had a combination of the markers. Most of the patients with neonatal/perinatal stroke were found to have at least 1 thrombophilia marker.

CONCLUSIONS

These data suggest that the prevalence of thrombophilia markers is increased in children with stroke compared with control subjects and, specifically, that FVL and APLA contribute significantly to stroke occurrence.

Lipoprotein (a) and Genetic Polymorphisms of Clotting Factor V, Prothrombin, and Methylenetetrahydrofolate Reductase Are Risk Factors of Spontaneous Ischemic Stroke in Childhood

Ischemic stroke is a rare event in childhood. In approximately one third of cases no obvious underlying cause or disorder can be detected. We investigated the importance of genetic risk factors of venous thromboembolism in childhood or stroke in adulthood as risk factors for spontaneous ischemic stroke in children. One hundred forty-eight Caucasian infants and children (aged 0.5 to 16 years) with stroke and 296 age-matched controls from the same geographic areas as the patients were analyzed for increased lipoprotein (a) [Lp(a)] levels >30 mg/dL; for the presence of the factor V (FV) G1691A mutation, the prothrombin (PT) G20210A variant, and the TT677 genotype of methylenetetrahydrofolate reductase (MTHFR); and deficiencies of protein C, protein S, and antithrombin. The following frequencies (patients v controls), odds ratios (ORs), and confidence intervals (CIs) of single risk factors were found: Lp(a) >30 mg/dL (26.4% v 4.7%; OR/CI, 7.2/3.8 to 13.8; P < .0001), FV G1691A (20.2% v 4%; OR/CI, 6/2.97 to 12.1; P < .0001), protein C deficiency (6% v 0.67%; OR/CI, 9.5/2 to 44.6; P = .001), PT G20210A (6% v 1.3%; OR/CI, 4.7/1.4 to 15.6; P = .01), and the MTHFR TT677 genotype (23.6% v 10.4%; OR/CI, 2.4/1.53 to 4.5; P < .0001). A combination of the heterozygous FV G1691A mutation with increased Lp(a) (n = 11) or the MTHFR TT677 genotype (n = 5) was found in 10.8% of cases, but only 0.3% of controls (OR/CI, 35.75/4.7 to 272;P < .0001). Increased Lp (a) levels, the FV G1691A mutation, protein C deficiency, the prothrombin G20210A variant, and the MTHFR TT677 are important risk factors for spontaneous ischemic stroke in childhood.

Lipoprotein (a) and Genetic Polymorphisms of Clotting Factor V, Prothrombin, and Methylenetetrahydrofolate Reductase Are Risk Factors of Spontaneous Ischemic Stroke in Childhood

Ischemic stroke is a rare event in childhood. In approximately one third of cases no obvious underlying cause or disorder can be detected. We investigated the importance of genetic risk factors of venous thromboembolism in childhood or stroke in adulthood as risk factors for spontaneous ischemic stroke in children. One hundred forty-eight Caucasian infants and children (aged 0.5 to 16 years) with stroke and 296 age-matched controls from the same geographic areas as the patients were analyzed for increased lipoprotein (a) [Lp(a)] levels &gt;30 mg/dL; for the presence of the factor V (FV) G1691A mutation, the prothrombin (PT) G20210A variant, and the TT677 genotype of methylenetetrahydrofolate reductase (MTHFR); and deficiencies of protein C, protein S, and antithrombin. The following frequencies (patients v controls), odds ratios (ORs), and confidence intervals (CIs) of single risk factors were found: Lp(a) &gt;30 mg/dL (26.4% v 4.7%; OR/CI, 7.2/3.8 to 13.8; P &lt; .0001), FV G1691A (20.2% v 4%; OR/CI, 6/2.97 to 12.1; P &lt; .0001), protein C deficiency (6% v 0.67%; OR/CI, 9.5/2 to 44.6; P = .001), PT G20210A (6% v 1.3%; OR/CI, 4.7/1.4 to 15.6; P = .01), and the MTHFR TT677 genotype (23.6% v 10.4%; OR/CI, 2.4/1.53 to 4.5; P &lt; .0001). A combination of the heterozygous FV G1691A mutation with increased Lp(a) (n = 11) or the MTHFR TT677 genotype (n = 5) was found in 10.8% of cases, but only 0.3% of controls (OR/CI, 35.75/4.7 to 272;P &lt; .0001). Increased Lp (a) levels, the FV G1691A mutation, protein C deficiency, the prothrombin G20210A variant, and the MTHFR TT677 are important risk factors for spontaneous ischemic stroke in childhood.

Plasma glutathione peroxidase deficiency and platelet insensitivity to nitric oxide in children with familial stroke

In a previous report by Freedman et al (J Clin Invest. 1996;97:979-987), plasma from 2 brothers with stroke or transient ischemic attack inactivated the antiplatelet effects of nitric oxide (NO), and this effect was found to be a consequence of a deficiency of plasma glutathione peroxidase (GSH-Px). In this study, we attempted to define the generalizability of this deficiency by studying NO-mediated antiplatelet effects in 7 families with familial childhood stroke. Seven families with familial childhood stroke that consecutively presented to a large referral center were included in the study. We monitored ADP-induced aggregation of normal gel-filtered platelets (GFP) in platelet-poor plasma (PPP) from normal individuals and from patients in the presence or absence of an NO donor (S-nitroso-glutathione). Surface P-selectin expression of normal GFP in patients' PPP was analyzed by flow cytometry after incubation with a P-selectin-specific monoclonal antibody in the presence or absence of the NO donor. We also measured GSH-Px activity in plasmas from family members and normal controls using standard methods. In 6 of 7 families, NO failed to inhibit platelet P-selectin expression and platelet aggregation in PPP from the affected family members and some of their relatives. Of 4 families studied, 3 probands and their corresponding affected parent had 50% decrease in plasma GSH-Px activity. In some patients with childhood stroke, impaired metabolism of reactive oxygen species as a result of reduced GSH-Px activity results in NO insufficiency that affects normal platelet inhibitory mechanisms and predisposes to arterial thrombosis.

Prevalence of the factor V leiden mutation in children and neonates with thromboembolic disease

OBJECTIVE

Resistance to activated protein C (APC) has been identified as a risk factor for thrombotic disease in adults. In over 90% of cases, the basis for the APC resistance is a mutation in the coagulation factor V gene (factor V Leiden) that renders the protein more resistant to inactivation by APC. We sought to determine the prevalence of the factor V Leiden (FVL) mutation in neonates and children who had experienced an arterial or venous thromboembolic event.

STUDY DESIGN

We retrospectively analyzed the clinical records of 33 neonates and 52 children with thromboembolic disease. Screening for the FVL mutation was performed by DNA analysis, allowing for identification of patients as normal, heterozygous, or homozygous.

RESULTS

Of the 85 patients studied, 12 (14.1%) were heterozygous for FVL; none were homozygous. Of the 47 patients who had arterial central nervous system events, 8 (17%) were positive for the FVL mutation, including 6 of 22 (27%) neonates. Of those patients who had a venous thrombosis, 4 of 32 (12.5%) were FVL positive. None of the 85 patients had protein C deficiency, 3.5% had protein S deficiency, 1.2% had antithrombin III deficiency, and 16.5% had anti-phospholipid antibodies.

CONCLUSION

These data suggest that the FVL mutation plays a role in the development of arterial and venous thrombotic events in neonates and children.

Role of factor V Leiden mutation in patients with angiographically demonstrated coronary artery disease

The study sought to determine whether coagulation factor V Leiden (FV Leiden) plays a role in the pathogenesis of coronary artery disease and/or myocardial infarction. Association of FV Leiden with venous thromboembolism is well established in the literature, but the role of the mutation in arterial thrombotic events is controversial. Some studies have documented an association between the mutation and myocardial infarction and stroke in juveniles. Few studies have explored its possible contribution to coronary atherosclerosis. We screened FV genotype in 850 predominantly white coronary angiography patients. Coronary artery disease risk factors and history of myocardial infarction were then analyzed by genotype. The FV Leiden mutation occurred in 54 (6.4%) patients. There was one homozygote; a 37-year-old, white male smoker with a history of myocardial infarction. Gene frequencies for white males and females were similar: 0.965 for the normal allele and 0.035 for FV Leiden. Gene frequencies for both genders were in Hardy-Weinberg equilibrium. FV Leiden was not a useful predictor (p=0.23) of the presence of clinically defined atherosclerosis (> or = 50% stenosis) in a logistic regression model adjusting for age, lipoprotein (a), total cholesterol, triglycerides, high density lipoprotein cholesterol, and fibrinogen. In addition, there was no difference in frequency of FV Leiden among those with and without medical histories of myocardial infarction (p=0.51). Allelic frequencies of FV Leiden in this patient group do not differ significantly from those reported for white populations. The FV Leiden mutation in its heterozygous state is not independently associated with coronary artery disease or myocardial infarction.

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.

Ischemic strokes in children

Ischemic stroke is an uncommon, but significant cause of disability in childhood. Children with strokes present with predictable deficits as adults do; however, fever and seizures at stroke onset are more common in children than in adults. Strokes in children have diverse etiologies and require extensive evaluation. Etiology remains obscure in up to half of the patients. Prognosis in childhood stroke is not benign and up to 50% of pediatric stroke patients have chronic sequelae. Emerging therapies may alter prognosis in certain populations of children at risk for stroke, but more research is necessary.

Motor speech impairment in a case of childhood basilar artery stroke: treatment directions derived from physiological and perceptual assessment

The perceptual and physiological characteristics of the speech of a nine year old child who suffered a basilar artery stroke at the age of five years were investigated using a battery of perceptual and physiological instrumental measures. Perceptual tests administered included the Frenchay Dysarthria Assessment, a perceptual analysis of a speech sample based on a reading of the Grandfather Passage and a phonetic intelligibility test. Instrumental procedures included: spirometric and kinematic analysis of speech breathing; electroglottographic evaluation of laryngeal function, nasometric assessment of velopharyngeal function and evaluation of lip and tongue function using pressure transducers. Physiological assessment indicated the most severe deficits to be in the respiratory and velopharyngeal sub-systems with significant deficits in the articulatory sub-system, all of which resulted in severely reduced intelligibility. These results were compared and contrasted with the subject's performance on the perceptual assessment battery. In a number of instances the physiological assessments were able to identify deficits in the functioning of components of the speech production apparatus either not evidenced by the perceptual assessments or where the findings of the various perceptual assessments were contradictory. The resulting comprehensive profile of the child's dysarthria demonstrated the value of using an assessment battery comprised of both physiological and perceptual methods. In particular, the need to include instrumental analysis of the functioning of the various subcomponents of the speech production apparatus in the assessment battery when defining the treatment priorities for children with acquired dysarthria is highlighted. Treatment priorities determined on the basis of both the perceptual and physiological assessments for the present CVA case are discussed.

Ischemic stroke in the elderly. Role of the common factor V mutation causing resistance to activated protein C

BACKGROUND AND PURPOSE

A common missense mutation in coagulation factor V (Arg 506 Gln) creates phenotypic resistance to the anticoagulant effects of activated protein C and predisposes carriers to venous thrombosis. To assess a correlation between this common hypercoagulable state and ischemic cerebrovascular disease, we have compared the prevalence of this mutation in a group of stroke patients with that in several control patient groups.

METHODS

The presence of the factor V Arg 506 Gln mutation was determined by a direct polymerase chain reaction-based assay on peripheral blood leukocytes from 161 elderly patients with acute ischemic stroke, 116 elderly patients with stroke risk factors but without acute stroke, 54 healthy elderly control subjects, and 287 younger control individuals (197 blood donors and 90 neonates).

RESULTS

The prevalence of the heterozygous Arg 506 Gln factor V mutation was not significantly different in the elderly stroke patients (2.5%) compared with either of the age-matched control groups (2% to 4%). The prevalence of this mutation was significantly higher in each of two younger control groups (approximately 8%) than in the elderly stroke patients (2.5%).

CONCLUSIONS

The common factor V Arg 506 Gln mutation predisposing to venous thrombosis is not a significant genetic risk factor for ischemic stroke in the elderly.

Activated protein C resistance: from phenotype to genotype and clinical practice

The anticoagulant protein C system is an important regulator of the blood coagulation process. Its targets are the procoagulant cofactors factor Va and factor VIIIa, which are cleaved and inactivated by activated protein C, protein S and intact factor V working as cofactors. Genetic defects of protein C or protein S were, together with antithrombin III deficiency, the previously established major causes of familial venous thromboembolism. However, these abnormalities are found in less than 5-10% of patients with thrombosis. Inherited resistance to activated protein C was recently identified as a major risk factor for venous thromboembolism. The activated protein C-resistance phenotype is found in 20-60% of the patients with venous thrombosis, depending on selection criteria and on the prevalence of activated protein C-resistance in the population. The frequency of activated protein C-resistance is 2-10% in the normal populations studied so far. In more than 90% of cases, the molecular background for the activated protein C-resistance is a single point mutation in the factor V gene, which predicts substitution of an arginine at position 506 by a glutamine. Mutated factor V is activated by thrombin or factor Xa in the normal way, but impaired inactivation of mutated factor Va by activated protein C results in a life-long hypercoagulability. Owing to the high prevalence of activated protein C-resistance in the population, it occasionally occurs in patients with deficiency of protein S, protein C or antithrombin III. Individuals with combined defects suffer more severely from thrombosis, and often at a younger age, than those with single defects, suggesting thrombophilia to be a multigenetic disease.

Ischemic stroke in young patients with activated protein C resistance. A report of three cases belonging to three different kindreds

BACKGROUND

A new pathological condition termed "activated protein C (APC) resistance" has recently been reported to be the most common hereditary blood coagulation disorder associated with familial thrombosis. APC resistance is characterized by a poor anticoagulant response to APC in the plasma of patients and is due to a defect of factor V.

CASE DESCRIPTIONS

This report deals with three Italian families with inherited APC resistance in which stroke had occurred at a young age in one of the family members. One of the patients exhibited ischemic stroke at 8 months of age. Although deep vein thrombosis is considered the main clinical manifestation of the defect, its possible association with stroke is discussed. DNA analysis confirmed the presence of the 1691GA mutation in the factor V gene (factor V Leiden) in all patients with a normalized APC sensitivity ratio of less than 0.70. In three cases the APC sensitivity ratios were very low (approximately 1.2), with a normalized APC sensitivity ratio of approximately 0.4. DNA analysis confirmed that these patients were homozygous for the mutation. The clinical history of these patients suggests that homozygosity for the defect is compatible with life and does not seem to be associated with early or more severe thrombophilia compared with homozygous defects of other clotting inhibitors.

CONCLUSIONS

The cases reported here suggest a possible association of inherited APC resistance with ischemic stroke in young patients. Case-control studies should be performed to assess the true association.