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Paediatric

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Genetic Disorders

Question
49 out of 49
 

A 18 year old primigravida complained of decreased fetal movements. She delivered a baby weighing 2000 gms at 30 weeks of gestation. The APGAR scores of the baby were 4 and 5 at 1 and 5 minutes respectively. The baby died in an hour. Postmortem examination revealed multiple, peripheral, radially arranged cysts in the kidney.

Most common associated finding in the baby would be: (DNB June 2011)



A Holoprosencephaly

B Hepatic cysts and hepatic fibrosis

C Ureteral agenesis

D Medullary sponge

Ans. A

Type 3 hypersensitivity

Immunologically mediated adverse drug been reactions have Ans. classified according to the GELL COOMBS CLASSIFICATION. The 4 types are:

1. Immediate hypersensitivity –

a. It occurs when the drug or drug metabolite interacts with preformed drug specific IgE antibodies that are bound to the surfaces of tissue mast cells and/or circulating basophils. Clinically manifests with urticaria, bronchospasm and anaphylaxis

b. Cytotoxic reactions - Involve IgG or IgM antibodies that recognize drug antigen on cell membrane. In the presence of serum complement, the antibody coated cell is either cleared by the monocytes or macrophage system or is destroyed. Examples include drug induced hemolytic anemia or thrombocytopenia.

2. Immune complex reactions (Type II hypersensitivity) –

a. It is caused by soluble complexes of drug or metabolite in slight antigen excess with IgG or IgM antibodies. The immune complex is deposited in blood vessel walls and causes injury by activating the complement cascade as seen in serum sickness.

b. Clinical manifestations include fever, urticaria, rash, lymphadenopathy, and arthralgias. Symptoms typically appear 1-3 weeks after the last dose of an offending drug and subside when the drug and/or its metabolites are cleared from the body.

3. Delayed hypersensitivity –

a. These are mediated by drug specific T lymphocytes. Commonly implicated drugs include neomycin and local anesthetics in topical formulations.

4. "Serum sickness like reactions

a. in which immune complexes have not been documented, which occur most commonly with cefaclor, may result from an inherited propensity for hepatic biotransformation of drugs into toxic or immunogenic metabolites."

b. From the above reference, it is clear that type III hypersensitivity to cefaclor can cause the clinical picture given in the question. Other options do not suit the clinical picture. The criteria for Kawasaki disease is not satisfied and IMN and partially treated meningitis do not present in this way.

Genetic Disorders Flashcard List

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