Pediatric severe factor XI deficiency: A multicenter study.

BACKGROUND: Factor XI (FXI) deficiency is a rare autosomal recessive bleeding disorder. Only scarce publications address its clinical features in children. The increased prevalence of FXI deficiency in Israel enabled data collection for this large multicenter cohort study. OBJECTIVE: Some hemostatic challenges may be unique or more common in children, such as bleeding in the neonatal period or trauma-related injury. The current study was designed to explore the potential impact of these differences in children with severe FXI deficiency. METHODS: Medical files of all children with FXI level under 15% followed at five tertiary centers were evaluated. The retrieved data comprised demographic and clinical characteristics, including bleeding episodes, surgical interventions, treatment strategies, as well as laboratory features. RESULTS: Sixty children, whose median age at diagnosis was 4.2 years and their median FXI level was 4%, were included. Three children experienced triggered intracranial hemorrhage (ICH) and two children had major bleeds. No bleeding complications occurred in surgeries in which hemostatic treatment consisting mostly of tranexamic acid or fresh frozen plasma was applied (n = 45). In contrast, excessive bleeding was noted in 25% of surgical procedures performed without hemostatic preparation (p = .002). CONCLUSION: This study's findings confirm the generally favorable outcome of this rare bleeding disorder, with no spontaneous bleeds or cases of perinatal ICH. Nonetheless, proper diagnosis and adequate hemostasis in the surgical setting are imperative. Unlike previous studies in adults, our pediatric study suggests an association between the severity of FXI deficiency and bleeding tendency.

A man-made disease: Fetal neonatal alloimmune thrombocytopenia due to incompatibility between oocyte donor and gestational mother.

The incompatibility causing fetal and neonatal alloimmune thrombocytopenia (FNAIT) results from a fetus inheriting a paternal human platelet antigen (HPA), which is different from the maternal HPA. We present a unique case of FNAIT in a pregnancy involving an oocyte recipient mother with Turner syndrome. This is the first report of FNAIT in which the suggested mechanism involves antibodies produced by a gestational mother against the incompatible HPA of the oocyte donor.

Nonarteritic anterior ischemic optic neuropathy is associated with a specific platelet polymorphism located on the glycoprotein Ibalpha gene.

OBJECTIVE: To evaluate the association between platelet glycoprotein polymorphisms and the risks of single and second eye involvement with nonarteritic anterior ischemic optic neuropathy (NAION). DESIGN: Case-control study. PARTICIPANTS: Ninety-two consecutive patients with NAION, 26 of whom had second eye involvement, and 145 controls who attended the eye clinic for nonvascular entities. METHODS: Polymerase chain reactions and restriction enzyme analyses were performed for genotyping 5 platelet glycoprotein polymorphisms on DNA extracted from whole blood. MAIN OUTCOME MEASURES: Frequencies of the various platelet polymorphisms. RESULTS: One of the 5 platelet glycoprotein polymorphisms analyzed, the B allele of the glycoprotein Ibalpha variable number of tandem repeats (VNTR), was a significant independent risk factor for NAION, with an odds ratio of 4.25 and a 95% confidence interval of 1.67 to 10.82 (P = 0.0026). All other platelet glycoprotein polymorphisms were similarly distributed in patients and controls. In addition, 9 of 16 patients who bore the VNTR B allele (56.3%) had second eye involvement, whereas among patients not harboring the VNTR B allele only 17 of 72 patients (23.6%) had second eye involvement (P = 0.009). Moreover, second eye involvement occurred earlier in patients who bore the specific polymorphism. CONCLUSIONS: The presence of the VNTR B allele of glycoprotein Ibalpha confers a significant risk for NAION and predisposes affected patients to second eye involvement.