Genetics in Obstetric Care

Question 1

What is Duchenne Muscular Dystrophy ?

Answer 1

This is an X-linked condition which is fatal in early adult life, carrier testing can be done as can parental testing and pre-implantation testing (for diagnosis prior to implantation)

Question 2

What is Autosomal Dominant Inheritance ?

Answer 2

In autosomal dominant inheritance each child has a 50% chance of inheriting the mutation as there are no “skipped generations”. These conditions are equally transmitted by men and women.

Question 3

What is an Autosomal Recessive Trait ?

Answer 3

Both parents are carriers.

Autosomal recessive inheritance means that the gene in question is located on one of the autosomes. These are numbered pairs of chromosomes, 1 through 22. Autosomes don’t affect an offspring’s gender. “Recessive” means that 2 non-working copies of the gene are necessary to have the trait or disorder.

Question 4

What causes CF ?

Answer 4

CF is caused by a defect of the cellular chloride transport within the cells, causing acute and chronic lung infections and dysfunction, also causing pancreatic insufficiency.

Question 5

How is a diagnosis of CF made?

Answer 5

Immunoreactive trypsin (first 6 weeks)
Sweat test
Genotyping

Question 6

What are some of the symptoms of sickle cell disorders ?

Answer 6

Pain+++
Cold
Dehydration
Infections
Jaundice
Anesthetic issues

Question 7

What is Tay-Sachs Disease ?

Answer 7

This is a progressive, genetic, lysosomal storage disease, the Hexosaminidase A (hex-A) deficiency results in the build up of lipid GM(2) ganglioside, especially in nerve cells in the brain.

Question 8

What is the progression of Tay-Sachs disease ?

Answer 8

Baby developmentally normal until ~6months then progressive neurological deterioration which is usually fatal by ~3-5 y/o

Question 9

How are new born babies screened for Tay Sachs disease ?

Answer 9

Clinical examination
Hearing
Blood spot (Dried blood spot - 5 days)

Question 10

What do the national programmes screen for with regards to genetic conditions ?

Answer 10

PKU
Congenital Hypothyroidism
SCD
CF

Question 11

How is PKU screened for ?

Answer 11

Biochemical screen.

Unable to break down phenylalanine (amino acid in protein)

Question 12

How are babies with congenital hypothyroidism treated ?

Answer 12

Thyroxine tablets from 21 days of age - stops disability.

Question 13

What is Medium Chain Acyl-CoA Dehydrogenase Deficiency (MCADD) ?

Answer 13

Lack the enzyme needed to metabolize fat into energy - difficult producing energy can be drowsy, vomiting, seizures and in some cases coma and death.

Question 14

How do you treat MCADD ?

Answer 14

Preventing metabolic rises by fasting and monitoring feeding to determine safe administration of glucose polymer and IV dextrose.