A novel homozygous missense mutation in the factor VII gene of severe factor VII deficiency in a newborn baby

Extensive genetic screening of Iranian Factor FVII-deficient individuals unraveled several novel mutations and postulated founder effects in some cases

Background

As the most frequent congenital rare bleeding disorder that transmits in an autosomal recessive manner, factor VII (FVII) deficiency is a serious bleeding complication in populations with high rate of in-marriages. While diagnosis mainly relies on clinical and laboratory phenotypes, plasma FVII antigen and activity levels do not often correlate with symptoms' severity.

Objectives

Genetic profiling of the affected individuals potentially improves our biological understanding of this complicated rare disorder.

Methods

Conventional polymerase chain reaction-Sanger sequencing and whole-exome sequencing were applied for genetic profiling of F7 gene in 66 symptomatic FVII-deficient individuals from 62 independent pedigrees. Thirty-nine asymptomatic relatives of the patients were also studied.

Results

Thirty different F7 pathogenic variations were identified in the studied cases of which 11 have not been reported before. The novel mutations include 5 missenses (c.715G>A, c.794T>C, c.1090C>G, c.1222C>A, c.1265T>C), 3 splicing (c.316+1G>T, c.682-2A>G, c.572-16C>G), 2 nonsenses (c.790delC, c.1248G>A), and 1 frameshift (c.1346delA). A founder effect is proposed for c.790delC that was detected in 8 independent pedigrees who were all from similar geographical regions and ethnic backgrounds. Homozygous c.790delC reduces plasma FVII activity to <1% and causes spontaneous intracranial hemorrhage in early infancy.

Conclusion

From the 66 studied symptomatic FVII-deficient individuals, 58 were homozygous carriers of the identified variations. Identification of homozygotes clarifies the potential role of nucleotide variations in reducing FVII activity and their contributions to a certain phenotype. Some of those variations, such as c.1A>G, c.509G>A, c.634C>T, and c.1285G>A have only been previously reported as heterozygous.

Evaluating for Suspected Child Abuse: Conditions That Predispose to Bleeding

Child abuse might be suspected when children present with cutaneous bruising, intracranial hemorrhage, or other manifestations of bleeding. In these cases, it is necessary to consider medical conditions that predispose to easy bleeding or bruising. When evaluating for the possibility of bleeding disorders and other conditions that predispose to hemorrhage, it is important for pediatricians to consider the child's presenting history, medical history, and physical examination findings before initiating a laboratory investigation. Many medical conditions can predispose to easy bleeding. Before ordering laboratory tests for a disease, it is useful to understand the biochemical basis and clinical presentation of the disorder, condition prevalence, and test characteristics. This technical report reviews the major medical conditions that predispose to bruising or bleeding and should be considered when evaluating for abusive injury.

Risk and Management of Intracerebral Hemorrhage in Patients with Bleeding Disorders

Intracerebral hemorrhage (ICH) is the most dreaded complication, and the main cause of death, in patients with congenital bleeding disorders. ICH can occur in all congenital bleeding disorders, ranging from mild, like some platelet function disorders, to severe disorders such as hemophilia A, which can cause catastrophic hemorrhage. While extremely rare in mild bleeding disorders, ICH is common in severe coagulation factor (F) XIII deficiency. ICH can be spontaneous or trauma-related. Spontaneous ICH occurs more often in adults, while trauma-related ICH is more prevalent in children. Risk factors that can affect the occurrence of ICH include the type of bleeding disorder and its severity, genotype and genetic polymorphisms, type of delivery, and sports and other activities. Patients with hemophilia A; afibrinogenemia; FXIII, FX, and FVII deficiencies; and type 3 von Willebrand disease are more susceptible than those with mild platelet function disorders, FV, FXI, combined FV-FVIII deficiencies, and type 1 von Willebrand disease. Generally, the more severe the disorder, the more likely the occurrence of ICH. Contact sports and activities can provoke ICH, while safe and noncontact sports present more benefit than danger. An important risk factor is stressful delivery, whether it is prolonged or by vacuum extraction. These should be avoided in patients with congenital bleeding disorders. Familiarity with all risk factors of ICH can help prevent occurrence of this diathesis and reduce related morbidity and mortality.

Novel IVS7+1G>T mutation of life-threatening congenital factor VII deficiency in neonates: A retrospective study in China

In neonates, congenital factor VII deficiency (FVIID) is characterized by central nervous system bleeding and gastrointestinal hemorrhage, often resulting in poor prognosis and high mortality.To improve understanding of FVIID in neonates in Asia, we retrospectively analyzed the clinical manifestations, diagnosis, treatment, clinical course, and genetic diagnosis of 2 cases of neonatal FVIID in the Department of Neonatology, Guangzhou Women and Children's Medical Center, Guangzhou, China, from January 2007 to December 2017 and performed a review of the relevant literature.Both neonates were female and presented with severe gastrointestinal tract and intracranial hemorrhage. The laboratory findings were characterized by repeated and non-vitamin K1-dependent prolonged of the prothrombin time (PT), Factor VII (FVII) activity was 1.5% and 3%, respectively. Both neonates died of severe intracranial hemorrhage, at 31 days and 6 months after birth, respectively. Gene sequencing results revealed a homozygous mutation in the FVII gene splice site (IVS7+1G>T) in both cases. Upon review of relevant literature published since 1996, we identified 19 cases of neonatal FVIID. The patients were full-term neonates with onset of symptoms mostly within 7 days after birth (73.7%), which included gastrointestinal bleeding (blood stool, vomiting blood; 31.6%), nervous system signs (drowsiness, convulsions, poor response; 26.3%), severe intracranial hemorrhage (84.2%), significantly prolonged PT with significantly decreased FVII activity (89.5%), high mortality, and disability (68.4%). Gene sequencing was performed in 9 of the 19 children evaluated and revealed a mutation in the FVII gene in all cases.FVIID can be clinically diagnosed based on the presence of prolonged PT that is difficult to correct and significantly decreased FVII activity (≤5%). As mutations in some sites are associated with severe bleeding, genetic diagnosis represents a useful tool for prenatal diagnosis of FVIID. In brief, we should pay great attention to the FVIID onset of the neonatal period, although it is rare but result in life-threatening bleeding with poor prognosis.

Evaluating for suspected child abuse: conditions that predispose to bleeding

Child abuse might be suspected when children present with cutaneous bruising, intracranial hemorrhage, or other manifestations of bleeding. In these cases, it is necessary to consider medical conditions that predispose to easy bleeding/bruising. When evaluating for the possibility of bleeding disorders and other conditions that predispose to hemorrhage, the pediatrician must consider the child's presenting history, medical history, and physical examination findings before initiating a laboratory investigation. Many medical conditions can predispose to easy bleeding. Before ordering laboratory tests for a disease, it is useful to understand the biochemical basis and clinical presentation of the disorder, condition prevalence, and test characteristics. This technical report reviews the major medical conditions that predispose to bruising/bleeding and should be considered when evaluating for abusive injury.

Recurrent mutations and genotype-phenotype correlations in hereditary factor VII deficiency in Korea

Coagulation factor VII (FVII) deficiency is a rare hereditary coagulopathy caused by mutations in the F7 gene. The aims of this study were to characterize the molecular defect of F7 in Korean patients with FVII deficiency and to find genotype-phenotype correlations. Study individuals consisted of 14 unrelated Korean patients with FVII deficiency with residual FVII activities ranging from 1 to 34%. To identify causative mutations, we performed PCR amplification and direct sequencing of all exons and flanking sequences of F7 gene. In all 14 patients, one (N = 4) or two (N = 10) mutant alleles were identified. A total of 11 unique mutations were detected, of which four were novel (c.-1C>T, p.V54RfsX53, p.R59_R60dupRR, and p.L314 V). Four recurrent mutations were observed in 86% of patients (12 of 14) (C389G, C115X, G343S, and c.572-1G>A) and accounted for 71% of all mutant alleles (17 of 24). The residual FVII activity was more than 5% in all six asymptomatic patients (21%, range 6-34%), whereas it was 5% or less in all eight symptomatic patients (2%, range 1-5%). In addition, the mean residual FVII activity in four patients with a single mutant allele was 23.6% (range 3-34%), which was significantly higher than that in 10 patients with two mutant alleles that was 4.6% (range 1-19%) (P = 0.023). In summary, the data from this study on the largest number of FVII deficiency in Korea showed recurrent mutations in this population and suggested genotype-phenotype correlations.