First Aid, Chapter 8, Immunologic Disorders, Complement Deficiencies

Question 1

What is the inheritance of complement deficiencies?

Answer 1

Complement deficiencies are inherited in an autosomal dominant manner except for properdin deficiency, which is inherited in an X-linked manner.

Question 2

What are primary complement deficiencies characterized by?

Answer 2

Primary complement deficiencies are characterized by recurrent infections and autoimmune diseases.

Question 3

What are the levels of CH50/AH50 or both, individual complement levels, two or more individual complement levels of CH50 or AH50, and complement split products in complement deficiency and complement consumption?

Answer 3

CH50/AH50 or both:
Complement deficiency - low
Complement consumption - low

Individual complement levels (eg C3):
Complement deficiency - low
Complement consumption - low

Two or more individual complement levels of CH50 or AH50:
Complement deficiency - low of individual component only
Complement consumption - low

Complement split products:
Complement deficiency - normal
Complement consumption - high

Question 4

What are features of early component (C1q, C1s, C2, and C4) deficiency?

Answer 4

Sinopulmonary infections Autoimmune disease (SLE-like)

Question 5

What are infectious organisms in early component (C1q, C1s, C2, and C4) deficiency?

Answer 5

S. Pneumoniae Haemophilus Influenzae (encapsulated organisms)

Question 6

What are the lab findings in early component (C1q, C1s, C2, and C4) deficiency?

Answer 6

decreased CH50

Question 7

What are the clinical features of C3 deficiency?

Answer 7

Severe infections (same as antibody deficiency) Glomerulonephritis

Question 8

What are the infectious organisms in C3 deficiency?

Answer 8

Encapsulated organisms (e.g., Neisseria sp.)

Question 9

What are the lab findings in C3 deficiency?

Answer 9

↓CH50 ↓AH50 ↓C3 C3 NeF: IgG anti-C3 autoantibodies

Question 10

What is the gene defect in C3 deficiency?

Answer 10

C3

Question 11

What are the clinical features of MBL deficiency?

Answer 11

Many asymptomatic; Autoimmune disease and respiratory infections

Question 12

What is the infectious organism in MBL deficiency?

Answer 12

Neisseria

Question 13

What are the lab findings in MBL deficiency?

Answer 13

decreased MBL

Question 14

What is the gene defect in MBL deficiency?

Answer 14

MASP2

Question 15

What are the clinical features of late component complement deficiency?

Answer 15

Infections (meningitis, arthritis, sepsis) and C5-7associated with autoimmunity

Question 16

What are the infectious organisms in late component complement deficiency?

Answer 16

Neisseria meningitidis (W135 and Y serotypes) and Neisseria gonorrhoeae

Question 17

What are the lab findings in late component complement deficiency?

Answer 17

↓CH50 ↓specific complement ↓AH50

Question 18

What are the clinical findings in alternative pathway (factor B, D, and properdin) deficiency? By what organism? What is the lab finding?

Answer 18

infections

Neisseria

decreased AH50

Question 19

Factor H deficiency is associated with which diseases?

Answer 19

Atypical hemolyticuremic syndrome (not associated with diarrhea) or glomerulonephritis and recurrent pyogenic infections due to secondary C3 deficiency. Polymorphism is associated with agerelated macular degeneration and HELLP syndrome (hemolytic anemia, elevated liver enzymes and low platelets, occurring during pregnancy.

Question 20

DAF (decay accelerating factor) and CD59 deficiency are associated with which disease?

Answer 20

Paroxysmal nocturnal hemoglobinuria