Clinical and genetic features of Chinese pediatric patients with severe congenital protein C deficiency who first presented with purpura fulminans: A case series study and literature review

Validation for the function of protein C in mouse models

Objectives

Protein C (PC) is an anticoagulant that is encoded by the PROC gene. Validation for the function of PC was carried out in mouse models.

Methods

In this study, autosomal recessive PC deficiency (PCD) was selected as the target, and the specific mutation site was chromosome 2 2q13-q14, PROC c.1198G>A (p.Gly400Ser) which targets G399S (GGT to AGC) in mouse models. To investigate the role of hereditary PC in mice models, we used CRISPR/Cas9 gene editing technology to create a mouse model with a genetic PCD mutation.

Results

The two F0 generation positive mice produced using the CRISPR/Cas9 gene editing technique were chimeras, and the mice in F1 and F2 generations were heterozygous. There was no phenotype of spontaneous bleeding or thrombosis in the heterozygous mice, but some of them were blind. Blood routine results showed no significant difference between the heterozygous mice and wild-type mice (P > 0.05). Prothrombin time (PT), activated partial thromboplastin time (APTT), and thrombin time (TT) were prolonged in the heterozygous mice, while the level of fibrinogen content (FIB) decreased, suggesting secondary consumptive coagulation disease. The protein C activity of heterozygous mice was significantly lower than that of wild-type mice (P < 0.001), but there was no significant difference in protein C antigen levels (P > 0.05). H&E staining showed steatosis and hydrodegeneration in the liver of heterozygous mice. Necrosis and exfoliated epithelial cells could be observed in renal tubule lumen, forming cell or granular tubules. Hemosiderin deposition was found in the spleen along with splenic hemorrhage. Immunohistochemistry demonstrated significant fibrin deposition in the liver, spleen, and kidney of heterozygous mice.

Conclusion

In this study, heterozygotes of the mouse model with a PC mutation were obtained. The function of PC was then validated in a mouse model through genotype, phenotype, and PC function analysis.

New plasma protein C and protein S concentrate: A synergy for therapeutic purposes

BACKGROUND AND OBJECTIVES

Deficiencies of protein C (PC) or protein S (PS) are rare diseases, characterized by mutations in the PC or PS genes, which encode plasma serine proteases with anti-coagulant activity. Severe PC or PS deficiencies manifest in early life as neonatal purpura fulminans, a life-threatening heamorrhagic condition requiring immediate treatment. First-line treatment involves replacement therapy, followed by maintenance with anti-coagulants. Replacement therapy with specific protein concentrates is currently only limited to PC, and therefore, a PC + PS concentrate represents a useful addition to therapeutic options, particularly for severe PS deficiency. Further, the production of a PC + PS concentrate from unused plasma fractionation intermediates would impact favourably on manufacturing costs, and consequently therapy prices for patients and health systems.

MATERIALS AND METHODS

Several chromatographic runs were performed on the same unused plasma fractionation intermediates using different supports to obtain a PC/PS concentrate. The best chromatographic mediums were chosen, in terms of specific activity and recovery. A full process of purification including virus inactivation/removal and lyophilization steps was set up.

RESULTS

The final freeze-dried product had a mean PC concentration of 47.75 IU/mL with 11% of PS, and a mean specific activity of 202.5 IU/mg protein, corresponding to over 12,000-fold purification from plasma.

CONCLUSION

The development of a novel concentrated PC/PS mixture obtained from a waste fraction of other commercial products could be used for its potential therapeutic role in the management of neonatal purpura fulminans pathology.

The clinical and genetic landscape of early-onset thrombophilia in Japan

OBJECTIVES

To determine the optimal management for early-onset thrombophilia (EOT), the genetic and clinical features of protein C (PC)-, protein S (PS)-, or antithrombin (AT)-deficient patients of ≤20 years of age were studied in Japan.

METHODS/RESULTS

Clinical and genetic information of all genetically diagnosed cases was collected through the prospective, retrospective study, and literature review. One-hundred-one patients had PC (n = 55), PS (n = 29), or AT deficiency (n = 18). One overlapping case had PC- and PS-monoallelic variant. Fifty-five PC-deficient patients (54%) had 26 monoallelic or 29 biallelic variant(s), and 29 (29%) PS-deficient patients had 20 monoallelic or nine biallelic variant(s). None of the patients had AT-biallelic variants. The frequent low-risk allele p.K193del (PC-Tottori) was found in five patients with monoallelic (19%) but not 29 with biallelic variant(s). The most common low-risk allele p.K196E (PS-Tokushima) was found in five with monoallelic (25%) and six with biallelic variant(s) (67%). One exceptional de novo PC variant was found in 32 families with EOT. Only five parents had a history of thromboembolism. Thrombosis concurrently developed in three mother-newborn pairs (two PC deficiency and one AT deficiency). The prospective cohort revealed the outcomes of 35 patients: three deaths with PC deficiency and 20 complication-free survivors. Neurological complications were more frequently found in patients with PC-biallelic variants than those with PC-, PS-, or AT-monoallelic variants (73% vs. 24%, p = .019).

CONCLUSIONS

We demonstrate the need for elective screening for EOT targeting PC deficiency in Japan. Early prenatal diagnosis of PC deficiency in mother-infant pairs may prevent perinatal thrombosis in them.

Neonatal Purpura Fulminans in a Patient With Arterial Thrombosis and Congenital Renal Agenesis

Neonatal purpura fulminans (PF) is an uncommon skin disorder characterized by acute disseminated intravascular coagulation, tissue necrosis, and small vessel thrombosis. Here, we present a case of a seven-day-old male who was admitted to the Neonatal Intensive Care (NICU) Unit at Gaafar Ibn Auf Tertiary Hospital, in January 2023. He presented with black bullous lesions on the plantar surface of the left foot, deep bluish discoloration over the right buttock and right lower abdomen, and gangrenous changes in the right foot with clear demarcation. Birth history was not significant other than mild pallor and icterus. His blood workup was consistent with severe anemia, thrombocytopenia, elevated prothrombin time, and partial thromboplastin time with decreased protein C and S levels; blood culture yielded no growth. A Doppler ultrasound scan of lower extremities confirmed distal occlusion of the right dorsalis pedis artery. The abdominal ultrasound revealed a free left renal bed and left-sided renal agenesis. We came to a diagnosis of neonatal PF and started administering blood and fresh frozen plasma and subcutaneous heparin injections, but unfortunately, the patient eventually passed away. Hence, we decided to report this case to emphasize the significance of the clinical picture in assisting with early diagnosis, despite limited access to genetic testing. We also want to highlight the importance of a "high index of suspicion" that might be mandatory for better outcomes.

Efficacy and safety of a hyperoxygenated fatty acid compound in improving the microcirculation of purpura fulminans in paediatric patients with sepsis: a pilot study

INTRODUCTION

Purpura fulminans (PF) is a serious complication of sepsis resulting from a set of alterations characterised by the development of ecchymotic haemorrhagic lesions and skin necrosis.

AIM

To analyse the efficacy and safety of the topical application of HOFA compound, in the cutaneous microcirculation of PF lesions in paediatric patients affected by sepsis.

MATERIAL AND METHODS

A prospective quasi-experimental pre-test/post-test single-group conducted in a Paediatric Intensive Care Unit of a third level hospital was performed. Paediatric patients aged 0-18 years with sepsis were included. Somatic oximetry values were measured before and after application of HOFAs every 4h over the first three days of the patients' hospitalisation. Patient's socio-demographic and clinical variables and somatic oximetry by placing a sensor for measuring tissue perfusion on the area with PF were determined.

RESULTS

Four patients were recruited, with a median age of 98 months. The purpuric lesions measured were mainly located on both feet and hands and, in two patients, also on the lateral malleoli and calves of both lower extremities. A total of 225 measurements were obtained, with mean pre-intervention scores of 71.17±15.65% versus 73.68±14.83% post-intervention. Statistical significance (p<0.001) was observed upon comparison of the pre- and post-intervention measurements.

CONCLUSIONS

Early and continued application of HOFAs in the management of sepsis-induced PF is an effective and safe practice in the cases analysed. In more than half of the episodes analysed, an increase in tissue microcirculation was observed after the application of HOFAs, with no adverse events.