Genetics and child health

Question 1

How does the size of the genetic fault you are looking for influence the genetic test you do ?

Answer 1

Question 2

Describe array comparative hybridisation testing

Answer 2

Array Comparative Genomic Hybridisation allows identification of regions of the genome that are deleted or duplicated in a patient by comparison with a control DNA sample.

Each dot on a microarray represents a specific genetic region. If more patient DNA than control DNA hybridises to the dot, it suggests that the region is duplicated in a patient.

If less patient DNA hybridises than control DNA, then the region is deleted in the patient.

Only detects chromosome inbalance i.e. not useful for balanced translocations

Question 3

How do we know a genetic change causes a disease ?

Answer 3

If the gene matches the phenotype -i.e. if the patient has 2 heads and it’s the gene which causes 2 heads then the gene matches the phenotype

Question 4

What is meant by a de novo mutation ?

Answer 4

When a genetic mutation occurs when a sperm fertilises an egg, or when cells are dividing after fertilisation. i.e. it is only present in the child

Question 5

Match the different type of mutation in the DNA sequence to the sentence:

• The cat sat on the mat
• The cat
• The car sat on the mat
• The cat spa to nth ema t
• The cas ato nt hem at
• The cat on the mat
• The cat cat sat on the mat

Wild type, instertion, triplet expansion, deletion (in frame), missense, deletion (out of frame), stop (nonsense)

Answer 5

• The cat sat on the mat - Wild type
• The cat - stop
• The car sat on the mat - Missense
• The cat spa to nth ema t - Insertion
• The cas ato nt hem at - Deletion (out of frame)
• The cat on the mat - Deletion (in frame)
• The cat cat sat on the mat - Triplet expansion

Question 6

What is meany by causative mutation ?

Answer 6

It is the mutation associated with the phenotype

Question 7

Define intellectual disability as per the education department

Answer 7

Those children and young people who have either a learning difficulty in relation to acquiring new skills or who learn at a different rate to their peers.

Question 8

What are the 3 main areas you should consider when thinking about someone potentially having intellectual disability ?

Answer 8

• Conceptual (ability to learn)
• Social (ability to interact)
• Practical (ability to dress themselves etc)

Question 9

What are some of the first line investigations to consider doing after history and examination for kids who possibly have a genetic disorder ?

Answer 9

First line:

• Creatinine Kinase, TFT’s, U+E’s, bone group, LFT’s, FBC and film
• Chromosomal microarray, Fragile X