Sickle cell disease is caused by a change (mutation) in a single gene that controls how your body makes hemoglobin, the oxygen-carrying protein in red blood cells.

What actually causes sickle cell?

At the root of sickle cell is a mutation in the HBB gene, which tells the body how to make part of hemoglobin (the beta-globin chain). This mutation creates an abnormal hemoglobin called hemoglobin S (HbS).

  • If a child inherits:
    • One HbS gene from each parent → they develop sickle cell disease (most commonly HbSS, also called sickle cell anemia).
* One HbS gene and one normal gene → they have “sickle cell trait” (usually no disease, but they can pass HbS to children).
  • The disease is inherited , not caught or caused by diet, infection, or lifestyle; you are born with it if both parents pass on the gene.

How does that mutation cause “sickle” cells?

When hemoglobin S is inside red blood cells and oxygen levels drop (for example, with dehydration, infection, or high altitude), it tends to stick to itself and form long rigid chains.

  • These chains stretch the red cell into a hard, curved “sickle” shape instead of a soft, flexible disc.
  • Sickled cells:
    • Break down faster, causing anemia (low red blood cell count).
* Get stuck in small blood vessels, blocking blood flow and leading to pain crises and organ damage.

An everyday picture: imagine soft rubber balls (normal red cells) rolling easily through tiny tubes; now replace them with brittle banana-shaped pebbles (sickle cells) that jam and crack.

Why does sickle cell run in some families and regions?

Because it is inherited, sickle cell disease and trait cluster in families and certain ancestries.

  • Higher likelihood if your family roots are from:
    • Africa
    • The Caribbean, Central or South America
    • Mediterranean countries
    • Middle East
    • South Asia (India and surrounding areas)
  • Historically, carrying one sickle cell gene (sickle cell trait) gave some protection against severe malaria, which is why the gene became more common in areas where malaria was or is widespread.

Triggers vs. causes

The cause is always the inherited HBB gene mutation, but certain things can trigger sickling and pain crises in someone who already has the disease.

Common triggers include:

  • Dehydration
  • Infection or fever
  • Very cold or very hot temperatures
  • Low-oxygen environments (high altitude, unpressurized flights)
  • Severe physical or emotional stress

These do not cause sickle cell to appear in someone who doesn’t carry the genes; they only worsen symptoms in someone who already has the condition.

Quick HTML table (causes vs. triggers)

html

<table>
  <thead>
    <tr>
      <th>Factor</th>
      <th>Role in sickle cell</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>HBB gene mutation (HbS)</td>
      <td>True underlying cause; changes hemoglobin and makes cells able to sickle.[web:1][web:5][web:9]</td>
    </tr>
    <tr>
      <td>Inheritance from both parents</td>
      <td>Needed for sickle cell disease (two abnormal copies); one abnormal copy causes trait.[web:1][web:7][web:9]</td>
    </tr>
    <tr>
      <td>Dehydration, cold, infection</td>
      <td>Triggers sickling and pain crises in people who already have sickle cell disease.[web:1][web:7][web:9]</td>
    </tr>
    <tr>
      <td>Region/ancestry (Africa, Mediterranean, etc.)</td>
      <td>Increases chance of carrying the gene but is not a direct cause by itself.[web:1][web:6][web:9]</td>
    </tr>
  </tbody>
</table>

Mini wrap-up (in plain words)

  • Sickle cell is not something you catch; it is a genetic blood disorder you are born with.
  • It happens because both parents pass on a changed hemoglobin gene (HBB), creating hemoglobin S that makes red cells stiff and sickle-shaped.
  • Triggers like dehydration or infection can worsen symptoms but are not the original cause.

Information gathered from public forums or data available on the internet and portrayed here.