Hi, this is Tom, and in this episode I'm going to be going through sickle cell disease,

and you can find notes at zero to finals.com and in the zero to finals pediatrics book,

and you can find flashcards and questions at members.0 tofinals.com.

So let's jump straight in.

Sickle cell disease is a genetic condition that causes sickle-shaped red blood cells.

The abnormal shape makes the red blood cells more fragile and easily destroyed,

leading to hemolytic anemia, where the red blood cells break down and the

patient becomes anemic. Patients with sickle cell disease are prone to various sickle cell

crises, which will go through in more detail. Let's start with the pathophysiology.

Hemoglobin is the protein in red blood cells that transports oxygen.

During fetal development, at around 32 to 36 weeks gestation,

fetal hemoglobin, or HBF, production decreases,

and adult hemoglobin, or HBAF, production decreases, and adult hemoglobin or HBA increases.

There is a gradual transition from HBF to HBA.

At birth, around 70 to 80% of hemoglobin is fetal hemoglobin and 20 to 30% is adult hemoglobin.

By six months, very little fetal hemoglobin is produced and red blood cells contain almost entirely adult hemoglobin.

Patients with sickle cell disease have an abnormal variant of hemoglobin called hemoglobin S or HBS.

HBS results in sickle-shaped red blood cells.

Sickle cell disease is an autosomal recessive condition caused by a mutation in the beta-globin gene on chromosome 11.

One abnormal copy of the gene results in sickle-cell trait.

Patients with sickle-cell trait are usually asymptomatic.

They are carriers of the condition. Two abnormal copies of the gene

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