Genetic Diseases 8.2

On your way to Biology mastery? Enrol in our 99.5 studyscore masterclass. Click here!

Inquiry Question 2: Do non-infectious diseases cause more deaths than infectious disease?

Content Descriptor: Investigate the causes and effects of non-infectious diseases in humans, including but not limited to:

Genetic diseases: (8.2.1)

Caused by genetic abnormalities

  • Pointmutations
  • Chromosomal mutations

Down syndrome:

  • Threecopies of chromosome 21 (trisomy 21)
  • Wideeyes
  • Shortflat nose
  • Heartdefects
  • Intellectuallearning difficulties
  • Assistance to those with down syndrome includes early intervention to help children developskills that help them in the community

Diseases caused by environmental exposure: (8.2.2)

Caused by genetic abnormalities

  • Exposureto toxic substances
  • Radiation
  • Drugabuse


  • Exposureto UV radiation (physical mutagen which breaks DNA backbone)
  • Pigment producing cells become cancerous when the tumour suppressor genes and cell deathregulatory genes become damaged
  • Removedthrough surgery
  • Significant harm prevented through sun-safety and early detection

Nutritional diseases: (8.2.3)

Caused by incorrect nutritional intake, an imbalance in diets


  • Lackin vitamin C
  • Loss of appetitedepression and weakness
  • Brittlebones
  • Preventedthrough consumption of fruit and vegetables

Cancer: (8.2.4)


Normal cells are programmed to die in a process called apoptosis, usually corresponding with the time that they have accumulated damage which prevents them from carrying out their normal function.

Cancer cells have mutated such that their regulatory genes have been switched off, allowing them to continue to replicate regardless of the damage they have accumulated.

Bowel cancer:

  • Inner liningrectum
  • Causesa hard-fibrous mass
  • Threat of metastasising and moving to the liver or lungs, where it can vastly affect vital cellfunction

Content Descriptor: Collect and represent data to show the incidence, prevalence and mortality rates of non-infectious diseases for example:

Nutritional diseases: (8.2.5)


Scurvy is a nutritional disease caused by vitamin C deficiency. It was first reported in 1550 BC, where the diagnosed symptoms were treated with onions and vegetables. Classical symptoms include brittle bones, bleeding gums and losing teeth, discoloured skin.

Primary risk factors include alcohol intake, tobacco use, haemodialysis and poor nutrition. Prevalence varies, from 7.1% in the USA to 73.9% in northern India.

In early human history the mortality rates were extremely high, around 50%. As seen in the diagrams below, the mortality rates for scurvy at the beginning of the 20th century began very high, at around 10%. However, soon following the publishing of the structure and synthetic production of vitamin C in 1927, as well as increased awareness and understanding of treatment, the mortality rate plummeted. Dying of scurvy is a very rare occurrence in developed nations.


        Scurvy mortality rates England


Diseases caused by environmental exposure: (8.2.6)


Melanoma, skin cancer has a number of associated risk factors. The leading cause is from exposure to UV radiation, which can cause the breaking of the DNA backbone or the formation of a thymine dimer. This may cause errors in cell regulatory genes, causing the uncontrolled growth cell growth and replication of cancers.

Characteristic symptoms can be a change in colouration or size of an existing mole, or abnormal change in skin colour.

Incidence of melanoma was 12,036 in Australia in 2012, with a mortality of 1,520. This number has increased to 15,229 in 2019. During the 1980’s, the incidence rose at a rate of 5% per year, and since 1990 it is increasing at 2.8% per year. This is likely reflective of increased awareness and prevention methods as a result of education campaigns. Currently, there is a 91% chance of surviving at least 5 years with melanoma. 

1/14 Australian men and 1/24 women will be diagnosed with melanoma in their lifetime, with current prevalence at 55,128.


      Melanoma incidence rates Australia

Inquiry Question Review: Do non-infectious diseases cause more deaths than infectious? (8.2.7)

You should be able to:

  • Describethe various causes of non-infectious diseases
  • Statestatistics relating to incidence, prevalence and mortality of these diseases

Sample Question:

Do non-infectious diseases cause more deaths than infectious?

Non-infectious disease is responsible for more deaths in developed nations, while infectious is responsible in developing nations. This can be attributed to a number of different factors: