Pathogenicity analysis of variations and prenatal diagnosis in a hereditary coagulation factor XIII deficiency family

Novel Insights into Heterozygous Factor XIII Deficiency

The prevalence and clinical significance of heterozygous factor XIII (FXIII) deficiency has long been debated, with controversial reports emerging since 1988. In the absence of large epidemiologic studies, but based on a few studies, a prevalence of 1 per 1,000 to 5,000 is estimated. In southeastern Iran, a hotspot area for the disorder, a study of more than 3,500 individuals found an incidence of 3.5%. Between 1988 and 2023, a total of 308 individuals were found with heterozygous FXIII deficiency, of which molecular, laboratory, and clinical presentations were available for 207 individuals. A total of 49 variants were found in the F13A gene, most of which were missense (61.2%), followed by nonsense (12.2%) and small deletions (12.2%), most occurring in the catalytic domain (52.1%) of the FXIII-A protein and most frequently in exon 4 (17%) of the F13A gene. This pattern is relatively similar to homozygous (severe) FXIII deficiency. In general, heterozygous FXIII deficiency is an asymptomatic condition without spontaneous bleeding tendency, but it can lead to hemorrhagic complications in hemostatic challenges such as trauma, surgery, childbirth, and pregnancy. Postoperative bleeding, postpartum hemorrhage, and miscarriage are the most common clinical manifestations, while impaired wound healing has been rarely reported. Although some of these clinical manifestations can also be observed in the general population, they are more common in heterozygous FXIII deficiency. While studies of heterozygous FXIII deficiency conducted over the past 35 years have shed light on some of the ambiguities of this condition, further studies on a large number of heterozygotes are needed to answer the major questions related to heterozygous FXIII deficiency.

Noninvasive prenatal diagnosis of congenital factor XIII deficiency in Iran

Congenital factor (F) XIII deficiency is a rare coagulation factor deficiency that is inherited in an autosomal recessive manner. FXIII deficiency presents various clinical manifestations, such as intracranial hemorrhage (ICH), which is the most common cause of morbidity and mortality. As ICH can occur in the neonatal period, prenatal diagnosis (PND) is an effective way to reduce neonatal ICH and its associated fatal consequences. In this study, we investigated a noninvasive prenatal diagnosis (NIPD) method, cell-free fetal DNA (cffDNA), for PND in FXIII deficiency. This study was conducted on seven pregnant women in the first trimester. After extraction of cffDNA from maternal plasma, PCR-restriction fragment length polymorphism (PCR-RFLP) was performed to find the underlying F13A gene mutations previously identified in the family members. PCR-RFLP was also performed on postnatal DNA samples. Sanger sequencing was performed to confirm the results. Four cases were heterozygous for F13A gene mutations, whereas three were unaffected. PCR-RFLP results for cffDNA and postnatal DNA samples were identical, and Sanger sequencing confirmed the results. cffDNA is a noninvasive and effective method for PND in congenital FXIII deficiency.

Prenatal diagnosis of factor 13 deficiency and its recurrence

A young third gravida was referred with prenatal diagnosis of factor XIII deficiency at 20 weeks of pregnancy for Medical Termination of Pregnancy (MTP). Her first baby, who was born by emergency Lower Segment Caesarean Section (LSCS) for fetal distress, had intracranial haemorrhage in the early neonatal period and was investigated elsewhere and diagnosed to have factor XIII deficiency. The child currently has global developmental delay and cerebral palsy. The mother had a second-degree consanguineous marriage and the couple were diagnosed to be carriers of factor XIII deficiency. She had lot of barriers to get prenatal diagnosis during the second pregnancy and it ended up in Intra Uterine Fetal Death (IUFD) at 27 weeks. During the current pregnancy, prenatal diagnosis (PND) was done only after the second trimester amniocentesis and the genetic mutation was F13 A1, Ex12, C.1687 G>A. Second trimester MTP in a previous scarred uterus was difficult as it is essential to avoid scar rupture. PND during the first trimester is ideal.