Minimal factor XIII activity level to prevent major spontaneous bleeds: comment

Factor XIII Deficiency: Laboratory, Molecular, and Clinical Aspects

Factor XIII-A (FXIII-A) deficiency is an ultra-rare bleeding disorder characterized by high rates of morbidity and mortality, primarily resulting from intracranial hemorrhage, umbilical cord bleeding, and miscarriage, whereas patients with severe FXIII-B deficiency present with a milder phenotype. Although the estimated incidence of severe FXIII-A deficiency is one per 2 million, a high prevalence ranging from 0.8 to 3.5% has been observed for heterozygous FXIII-A deficiency. Unlike most bleeding disorders, individuals with heterozygous FXIII-A deficiency, particularly women, are more likely to experience hemorrhagic complications during hemostatic challenges. About 200 Mutations have been observed in F13A and F13B genes, with most being missense mutations, while large deletions are the rarest. There is no correlation between genotype and phenotype and a moderate to strong correlation between factor activity and clinical severity in FXIII-A deficiency, making it difficult to predict bleeding patterns based on genotype and FXIII activity levels. Primary prophylaxis is mandatory for all patients with severe FXIII-A deficiency, while those with heterozygous deficiency are generally asymptomatic and may require on-demand therapy during hemostatic challenges, most commonly in women. On the other hand, patients with severe FXIII-B deficiency may only require on-demand therapy, while heterozygotes are generally asymptomatic. Although there are general recommended therapeutic regimens for prophylaxis or on-demand therapy in different situations, personalized pharmacokinetic-based replacement therapy represents the optimal approach that can optimize intervention efficacy. In such an approach, several factors may affect the effectiveness of treatment and determine the dose and type of intervention, including the classification of FXIII deficiency, residual plasma levels of FXIII, clinical situation requiring intervention, age, weight, and also gender.

Gynecological and obstetric outcome in the French cohort of women with factor XIII deficiency

INTRODUCTION

Congenital factor XIII deficiency is a very rare bleeding disorder affecting 33 patients in France. Besides its role in fibrin clot stabilization, factor XIII is involved in placental attachment. Fetal miscarriages represent a frequent and concerning issue for these patients. The aim of the present study was to describe clinical characteristics of women presenting severe congenital FXIII deficiency in France, to focus on gynecological and obstetrical events, and to report the management of these rare situations.

METHODS

We conducted a retrospective study in the French Hemophilia Comprehensive Care and Clinical Hemostasis Centers. Women between 15 and 65 years with factor XIII activity <10 IU dL^-1 were included. Biological, clinical and therapeutic events that occurred to these patients during their gynecological and obstetrical period were recorded.

RESULTS

Among 31 centers, eleven patients were included. The median age at diagnosis was 1.5 years (range: 0-35), and at inclusion it was 30 years (range: 15-63). Fetal miscarriage was the primary manifestations in 2 (18%) patients, the remaining were diagnosed during hemorrhage. Menorrhagias were reported by 2 women (27%), 13 pregnancies were reported by 9 women including one abortion. Every pregnancy was conducted under factor XIII substitution, no hemorrhagic episode was reported. Four patients (36%) experienced at least one fetal miscarriage with a total amount of 30 miscarriages with 6 occurring during substitution.

CONCLUSION

Altogether, our data confirmed the high incidence of miscarriage in women with factor XIII deficiency. Good outcome of pregnancies required prophylaxis in accordance with international guidelines.

Congenital factor XIII deficiency: comprehensive overview of the FranceCoag cohort

This FranceCoag network study assessed 33 patients with congenital factor XIII (FXIII) deficiency presenting FXIII levels <10 iu/dl. Diagnosis was based on abnormal bleeding in 29 patients, a positive family history in 2, recurrent miscarriages in 1 and was fortuitous in 1. Eighteen patients (62·1%) presented life-threatening umbilical or intracranial haemorrhages (ICH). Seven of the 15 patients who experienced ICH were diagnosed but untreated, including 3 with secondary neurological sequelae. All pregnancies without prophylaxis (26/26) led to miscarriages versus 3/16 with prophylaxis. In patients exhibiting FXIII levels <10 iu/dl, prophylaxis could be discussed at diagnosis and at pregnancy. Further controlled prospective studies are needed.