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Related Experiment Video

Updated: May 22, 2025

Measurement of Factor V Activity in Human Plasma Using a Microplate Coagulation Assay

Measurement of Factor V Activity in Human Plasma Using a Microplate Coagulation Assay

Published on: September 9, 2012

Two New Kindreds with Complete Factor D Deficiency.

Mathilde Puel¹, Kenza Rwayane¹, Paula Vieira Martins¹

¹Department of Immunology, Assistance Publique- Hôpitaux de Paris (AP-HP), Georges Pompidou European Hospital, Paris, France.

European Journal of Immunology

|March 12, 2025

Summary

This summary is machine-generated.

Two new cases of complete factor D (FD) deficiency were identified, one in a patient with Down syndrome. This highlights the need to investigate complement system deficiencies, especially the alternative pathway (AP), in individuals with recurrent infections.

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Area of Science:

Immunology
Genetics

Background:

Inborn deficiencies of the alternative pathway (AP) of the complement system are linked to severe infections, primarily from encapsulated bacteria.
Complete factor D (FD) deficiency is rare, with only seven families previously reported.

Purpose of the Study:

To report two new cases of biochemically and genetically confirmed complete FD deficiency.
To emphasize the importance of investigating the complement system in patients with Down syndrome and other secondary immune deficiencies.

Main Methods:

Biochemical assays to measure FD activity and levels (ELISA).
Genetic analysis of the CFD gene to identify causative variants.
Clinical case reporting and literature review.

Main Results:

Two patients with complete FD deficiency were identified, experiencing severe infections with H. influenza and N. meningitidis.
FD activity was undetectable and restored by recombinant human FD; ELISA confirmed undetectable FD levels.
Genetic analysis revealed a homozygous missense variant (p.M40R) in one patient and compound heterozygous variants (p.Cys148* and c.212+2T>G) in the other.

Conclusions:

This study reports the first case of complete FD deficiency in a Down syndrome patient, underscoring the need for complement system evaluation in this population.
Inherited complete FD deficiency necessitates preventive strategies against encapsulated bacteria, particularly for individuals on therapeutic MASP-3 or FD inhibitors.