Sickle-Cell Anaemia

In sickle-cell anaemia what is the abnormal haemoglobin variant?

Haemoglobin S (HbS) rather than HbA

What is the mode of inheritance of sickle-cell anaemia?

Autosomal recessive

In sickle-cell anaemia on which chromosome is the affected gene?

Chromosome 11

In sickle-cell anaemia which gene is affected?

Beta-globin gene

What amino acid substitution results in the production of HbS?

Substitution of valine for glutamic acid as the 7th amino acid of the beta-globin chain

What form of the condition does homozygous HbSS result in?

Sickle-cell anaemia

What form of the condition does heterozygous HbAS result in?

Sickle-cell trait

How does sickle-cell trait affect malaria?

Malaria is less severe with protection against Falciparum malaria

How is sickle-cell anaemia testing performed in a newborn?

Heel prick test

How soon after birth is sickle-cell anaemia tested in a newborn?

5 days of age

List 2 typical findings on blood film

1) Sickle cells

2) Target cells

What is the diagnostic test for sickle-cell anaemia?

Haemoglobin electrophoresis

In sickle-cell anaemia which antibiotic is given as prophylaxis against infection?

Phenoxymethylpenicillin (penicillin V)

List 4 triggers of sickle-cell crisis

1) Infection

2) Dehydration

3) Cold weather

4) Emotion / life events

Which infection commonly triggers aplastic crisis in sickle-cell anaemia?

Parvovirus B19

What is the commonest presentation of a sickle-cell crisis?

Vaso-occlusive (painful) crisis

What urological emergency may present as a sickle-cell crisis?

Priapism – prolonged painful erection due to vaso-occlusion

In sickle-cell anaemia what is the commonest cause of mortality?

Chest crisis