Question

(a) State the cause and symptoms of Down’s syndrome. Name and explain the event responsible for causing this syndrome. (b) Haemophilia and Thalassemia are both examples of Mendelian disorder, but show difference in their inheritance pattern. Explain how.

Answer 1

A genetic disorder, Down syndrome is a chromosomal abnormality in certain people which causes:

intellectual disability, cognitive disabilities, physical growth delays, characteristic facial features, digestive issues such as blockage of intestines, defects hearing or vision problems

cause of down syndrome

When a baby’s cells develop each cell receives 23 pairs of chromosomes, i.e. a total of 46 chromosomes, half from the mother and half from the father. People with Down syndrome have an extra chromosome i.e. a total of 47 chromosomes. Medical experts are not sure why this occurs. 

No link has been established so far between the environment (such as lifestyle, including diet) and the extra chromosome or the parents from whom the child receives the genes.  

SYMPTOMS of Down syndrome

short neck which also appears rather flat with excess skin at the backeyes slant upwards a bit and are almond shapedthe outer part of the iris in the eyes might have light spots that are called Brushfield spotsbridge of the nose is small which gives the impression of a button and broad nosesmall ears and headflattened facial profileshort and chubby fingersshort handslow and poor muscle tone which affects all the muscles in the bodyA gap between the big toe and the rest of the toes