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Condition report · Immunological

Complement Deficiencies

Inherited deficiencies of the complement system, a group of blood proteins that help the immune system clear bacteria and immune complexes. Depending on the component affected, they raise the risk of recurrent infections, particularly meningococcal disease, or of lupus-like autoimmune disease.

A condition report looks for rare variants known to cause the conditions it covers.

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What your report covers

The 6 conditions we analyse

Early classical pathway complement deficiency (C1q, C1r/C1s, C2, C4)

Autosomal recessive

Deficiencies of the early components of the classical complement pathway, which are associated with lupus-like autoimmune disease and some bacterial infections.

What a diagnosis changes

Knowing the diagnosis supports early recognition of autoimmune disease and appropriate vaccination.

Genes analysed

Also known as

immunodeficiency due to a C1, C4, or C2 component complement deficiency; immunodeficiency due to an early component of complement deficiency; immunodeficiency due to C1, C4, or C2 component complement deficiency

Includes 9 related subtypes ↓
  • C1Q deficiency
  • C1Q deficiency 1
  • C1Q deficiency 2
  • C1Q deficiency 3
  • complement component 2 deficiency
  • complement component 4a deficiency
  • complement component 4b deficiency
  • complement component C1r/C1s deficiency
  • complement component C1s deficiency
MONDO:0015699Orphanet 169147MedGen 585054

Complement component 3 deficiency

Autosomal recessive

Caused by changes in C3, it leads to severe recurrent bacterial infections and can cause kidney inflammation.

What a diagnosis changes

Vaccination against encapsulated bacteria and prompt treatment of infections reduce the risk of serious illness.

Genes analysed

Also known as

C3 classic complement early component deficiency; C3 deficiency; C3d; classic complement early component deficiency caused by mutation in C3; complement component 3 deficiency, autosomal recessive

MONDO:0013417OMIM 613779Orphanet 280133MedGen 462421

Late complement component deficiency (C5 to C9)

Autosomal recessive

Deficiencies of the terminal complement components that greatly increase the risk of recurrent Neisseria infections, especially meningococcal disease.

What a diagnosis changes

Meningococcal vaccination, and in some cases antibiotic prophylaxis, are recommended.

Genes analysed

Also known as

deficiency of complement of terminal pathway; immunodeficiency due to a C5 to C9 component complement deficiency; immunodeficiency due to C5 to C9 component complement deficiency; terminal complement pathway deficiency

Includes 6 related subtypes ↓
  • complement component 5 deficiency
  • complement component 6 deficiency
  • complement component 7 deficiency
  • complement component 9 deficiency
  • type I complement component 8 deficiency
  • type II complement component 8 deficiency
MONDO:0015700Orphanet 169150MedGen 585067

Complement factor I deficiency

Autosomal recessive

Caused by changes in CFI, it leads to uncontrolled complement consumption and recurrent bacterial infections.

What a diagnosis changes

Vaccination against encapsulated bacteria and prompt treatment of infections reduce the risk of serious illness.

Genes analysed

Also known as

C3 inactivator deficiency; CFID; complement component 3 inactivator deficiency

MONDO:0012594OMIM 610984Orphanet 200418MedGen 483045

Complement factor D deficiency

Autosomal recessive

Caused by changes in CFD, it impairs the alternative complement pathway and predisposes to Neisseria infections.

What a diagnosis changes

Meningococcal vaccination is recommended.

Genes analysed

Also known as

CFDD; complement factor D deficiency

MONDO:0013487OMIM 613912Orphanet 169467MedGen 97989

Properdin deficiency, X-linked

X-linked recessive

Caused by changes in CFP, it affects mainly males and predisposes to severe meningococcal disease.

What a diagnosis changes

Meningococcal vaccination of affected males reduces the risk of severe infection.

Genes analysed

Also known as

CFPD; PFD; properdin deficiency, X-linked, X-linked recessive

MONDO:0010713OMIM 312060Orphanet 2966MedGen 333322

Limitations

  • The C4A and C4B genes lie in a region with variable copy number and highly similar sequence, so C4 deficiency cannot be reliably detected from short-read sequencing.

Other immunological conditions

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