Module 1 | Lesson 2

Genotypes Explained

Welcome to Lesson 1 of Module 1

Estimated time: 12-15 minutes
Main activity: Watch the short video and complete the reflection activity and knowledge quiz

What You Will Learn In This Lesson

Not all sickle cell disease is the same. Understanding different genotypes helps professionals recognise how symptoms, complications and support needs may vary from person to person.

Watch the Video

Watch the short video that provides a quick explaination, before moving on to explore genotypes and their role in sickle cell in more detail.

Learning Outcomes

By the end of this lesson, you will be able to:

  • Explain what a genotype is.
  • Describe the main sickle cell genotypes seen in clinical practice.
  • Recognise why genotype influences severity but does not predict an individual’s experience.
  • Avoid common misconceptions about “mild” and “severe” disease.

Before You Watch

Think about the following question:

Have you ever assumed someone’s sickle cell condition was “mild” simply because of their genotype?

Keep that thought in mind while watching.

Play

Key Learning Points

What is a Genotype?

A genotype describes the specific combination of haemoglobin genes a person inherits from their parents.

Everyone inherits:

  • one haemoglobin gene from their mother
  • one haemoglobin gene from their father

The combination of these genes determines which type of sickle cell disease a person has. Here are 4 genotypes and how they impact people.

HbSS

Often called Sickle Cell Anaemia

Usually the most severe and most common form.

People may experience:

  • frequent pain crises
  • anaemia
  • organ complications
  • increased infection risk

However, severity varies considerably between individuals.

HbSC

Usually produces milder anaemia than HbSS.

However, people can still experience:

  • painful crises
  • acute chest syndrome
  • eye complications
  • avascular necrosis

Many people with HbSC require significant medical support.

HbSβ⁰ Thalassaemia

Produces little or no normal haemoglobin.

Often behaves similarly to HbSS.

Symptoms can include:

  • severe anaemia
  • pain crises
  • organ complications

HbSβ⁺ Thalassaemia

Some normal haemoglobin is still produced.

Symptoms are often milder than HbSS, but there is considerable variation.

Some individuals experience frequent complications despite having this genotype.

Why Genotype Matters

Genotype helps guide care, but it never tells the whole story.

Two people with exactly the same genotype can have very different experiences.

Factors influencing health include:

  • hydration
  • infections
  • temperature
  • stress
  • access to healthcare
  • treatment adherence
  • genetics beyond haemoglobin alone

Always assess the person, not just the genotype.

Downloadable Resources

Genotype Quick Reference Guide (PDF)

A printable comparison sheet summarising the four major sickle cell genotypes.

Clinical Myth vs Reality Knowledge Sheet

A quick reference for common misconceptions and evidence-based facts

Patient-Friendly Genotype Explanation

A plain English handout professionals can use when discussing genotypes with patients and families.

Reflection Activity

Consider this scenario:

Two patients attend your service. Both have sickle cell disease. One has HbSS and the other has HbSC.

The patient with HbSC reports severe pain, but a clinician assumes it “can’t be that bad.”

Reflect on:

  • What assumptions have been made?
  • How might these affect the patient’s care?
  • How could you respond differently?
Complete Reflection Activity

Myth vs Reality

Reality: Many people with HbSC experience severe pain crises and serious complications.

Reality: Genotype is only one part of the picture.

Reality
Many treatments are similar, but monitoring and complications may differ.

Quick Comparison Table

Genotype

HbSS

HbSC

HbSβ⁰

HbSβ⁺

Typical Severity

Usually more severe

Variable

Similar to HbSS

Variable

Key Points

Most common genotype

Can still cause serious complications

Little or no normal haemoglobin

Some normal haemoglobin produced

Knowledge Check

Complete the short knowledge check before moving to the next lesson.

Start Knowledge Check

Key Takeaways

  • Genotype refers to the inherited haemoglobin genes.
  • Different genotypes can influence complications and management.
  • Severity varies greatly between individuals.
  • Treat the person, not the label.

Continue Your Learning

Excellent work! You now understand the main sickle cell genotypes and why they matter in practice.

← Back to Module 1 Overview Continue to Lesson 3 – How Sickle Red Blood Cells Cause Problems →