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what is the cause of hereditary angioedema?
C1 esterase inhibitor deficiency
in SCID, what is there a deficiency of?
- absent B and T cells
- so look at lymphocyte subsets - see if both absent
when does SCID present?
first 6 months of life - unusual infection and severe FTT
which infections commonly occur in SCID?
- oral candida
- chronic diarrhoea
- ear infections
what is the inheritance of SCID?
what is Rx of SCID?
bone marrow transplantation
what is the most common cause of Ig deficiency?
x-linked agammaglobulinaemia: failure of B cell development and Ig production.
when does x-linked gamma present?
- first 2yrs life
- severe bacterial infections - sinopulmonary
which gene causes x-linked agammaglob?
bruton tyrosine kinase
what is ataxia telangiectasia? inheritance?
- auto recessive
- affects cerebellum - ataxia
- get immune system weak - respiratory disorder and cancer
what is the gene in ataxia telangiectasia responsible for?
DNA repair gene
what is the triad in wiskott-aldrich syndrome?
- thrombocytopenia - so may need splenectomy
what is the inheritance of wiskott-aldrich syndrome?
what is curative for wiskott-aldrich syndrome?
what causes DiGeorge syndrome - maldevelopment of…
- 5th branchial arch causing heart
- Abnormal facies
- Thymus aplasia
- Cleft palate
- Hypocalcaemia (due to low PTH)
what are the causes of secondary immunodeficiency?
- immunosuppression drugs - chemotherapy, steroids,
- nephrotic syndrome
- bacterial and viral infections
which tests are used to assess immune function in children?
- lymphocyte subsets
- specific Ig
- Neutrophils NBT - chronic granulomatous disease
- adhesion molecules
which 2 types of inheritance is most primary immunodeficiency?
x-linked or AR
what needs to be asked in history of immunodef?
- FH of consanguinity
- unexplained death - boys
what are the clinical features in most primary immunodef?
- protein losing enteropathy
what are the 3 main arms of Rx of primary immunodef - other than gene therapy!
- antibiotic prophylaxis - PCP co-trimoxazole
- antibiotic therapy when infection happens
- Ig replacement if defective antibody production or function
- BM transplant in severe immunodef
which primary immunodef leads to chronic bacterial and fungal infections?
- chronic granulomatous disease
- phagocytic cells fail to produce superoxide after ingestion of microorganisms
- need prophylactic abx and INF gamma
what is delayed separation of the umbilical cord a classical features of?
- leucocyte adhesion deficiency
- also get delayed wound healing, chronic skill ulcers, deep seated infection (remember the WBC cant get there!!)
which primary immunodef would benefit greatly from prophylactic antibiotics?
chronic granulomatous disease
which 1ry immunodef has defect in the bruton tyrosine kinase gene?
x linked agammaglobulinaemia
how may complement deficiency present?
with a viral infection - which cell has a rapid response?
natural killer cell response
which infections do cytotoxic T cells attack?
what are the main causes of secondary immunodeficiency in children?
- immunosuppressive therapy eg cytotoxic drugs and steroids
what is the consequences of cytotoxic drugs?
- eg in ALL
- chemo is very immunosuppressive as BM suppression and neutropenia
- if febrile neutropenia then at risk of potentially fatal bacterial and fungal infections
why would a child be taking high dose steroids?
what are potential problems with taking steroids?
what are children who have had organ transplants at risk of?
what are the ways of HIV transmission to children?v
- vertical transmission
- blood products
what are the 3 main routes of vertical transmission?
- breast feeding
when do children have their mothers HIV antibodies until?
15-18 months, then disappear
how is HIV diagnosed in children - what test?
- HIV viral culture: gold standard, but not widely available
- PCR for viral genome
what is the incubation of HIV in children cf to adults?
shorter in perinatally infected children
what % of the CD4 count do you need for moderate immunosupp?
what % of CD4 count gives severe immunosupp?
what are symptoms of mild HIV?
what are symptoms of moderate HIV?
- severe bacterial infection
- chronic diarrhoea
- lymphocytic interstitial pneumonitis
what are symptoms of severe HIV ie AIDS?
- wasting as FTT
- opportunistic infection eg PCP
- severe bacterial infection
what are the neurological complications of AIDS?
- motor defect
what are the GI complication of AIDS?
- wt loss
what are the skin condition in AIDS
what is management of paediatric HIV?
- co-trimoxazole PCP prophylaxis
- primary immunisation course should be given
- BCG not recommended
- defer MMR if severely immunosupp
- antiretroviral Rx if symptomatic or CD4<15% - RT inhibitor and protease inhibitors
how is paediatric HIV prevented?
- antenatal screening for HIV
- zidovudine during pregnancy, delivery and to neonate for 6 weeks
- reduces vertical transmission of HIV1
- C/S unless low viral load can have vaginal delivery