Human Genetic Disorders
Some disorders are caused by gene or chromosome changes.
About this topic
Genetic disorders arise from altered genes or chromosomes. Single-gene disorders include cystic fibrosis (recessive), sickle-cell anaemia (recessive), Huntington's disease (dominant) and haemophilia (X-linked). Chromosomal disorders, such as Down's syndrome (extra chromosome 21) and Turner syndrome (X0), involve changes in number.
Screening, genetic testing and counselling help families. Some treatments manage symptoms, while gene therapy aims to correct faulty genes. Sickle-cell carriers gain malaria resistance, an example of a trade-off.
Cystic fibrosis is caused by a faulty chloride channel gene, causing thick sticky mucus in the lungs and gut; about 1 in 25 people of European descent are carriers. Down syndrome results from three copies of chromosome 21 and becomes more likely with maternal age. Turner syndrome is one X chromosome only, and Klinefelter syndrome is XXY. Huntington's disease usually shows up in adulthood.
Screening, such as newborn heel-prick tests for phenylketonuria, lets doctors begin treatment early; PKU is managed by diet. Prenatal tests include amniocentesis and chorionic villus sampling. Some disorders involve ethical choices, for instance about embryo screening. Students should avoid saying disorders are always inherited; many chromosome conditions arise by chance, and many conditions such as heart disease involve both genes and environment.
Key ideas
- Cystic fibrosis is recessive
- Down syndrome is trisomy 21
- Sickle cell is codominant-like
Quick check
Use cases: where Human Genetic Disorders helps
- Homework: review the key idea behind Human Genetic Disorders before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Human Genetic Disorders without notes.
- Visual learning: play with the interactive lab to see how Human Genetic Disorders changes when you adjust its inputs.
- Teaching a friend: explain Human Genetic Disorders in your own words, then compare your version with the key ideas.
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Frequently asked questions
What is Human Genetic Disorders?
Some disorders are caused by gene or chromosome changes.
What will I learn in Human Genetic Disorders?
Cystic fibrosis is recessive. Down syndrome is trisomy 21. Sickle cell is codominant-like.
Is Human Genetic Disorders part of Biology?
Yes. It is one of 150 Biology topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Human Genetic Disorders lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Human Genetic Disorders?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.