Genetics in clinical practice 2

Question 1

Types of genetic tests

Answer 1

standard chromosome analysis, fluorescent in situ hybridisation (FISH), comparitive genomic hybridisation arraay (Array CGH), single gene testing, next generation sequencing, methylation analysis (imprinting disorders)

Question 2

VACTERL association what

Answer 2

Disorder that affects many body systems:
Vertebral
Anal atresis
Cardiac
Tracheo-oesophageal atresia, phistula
Renal abnormalities
Limb (radial ray defect)

Question 3

Aneuploidy and polyploidies define

Answer 3

Aneuploidy-(chromosome number not dicisible by 23)

Polyploidy–multiple sets of 23 chromosomes

Question 4

Aneuploidy what is it caused by

Answer 4

Non disjunction during meiosis so that gamete has one more or less chromosome->gamete fusion would cause 1 more c’some (trisomy) or 1 less c’some (monosomy)

Question 5

Which chromosomes are wrong in Down’s and Patau

Answer 5

Down’s-trisomy 21

Patau-trisomy 13

Question 6

Velocardiofacial syndrome symptom and cause

Answer 6

Symptom: CHD, cleft andd/or palate, absent thymus, absent parathyroid glands, dysmorphic features, learning difficulties
Cause: deletion of 22q11.22

Question 7

Comparative genomic hybridisation array what does it do and which conditions is it used for

Answer 7

Identifies small genomic imbalances which may have effect on individual’s health+development or confer increased susceptibility to certain conditions: autism, psychiatric disease, congenital abnormalities

Question 8

What can del116p11.2 be detected by

Answer 8

this is a microdeletion so aCGH

Question 9

What is single gene testing used for

Answer 9

Diagnosis/confirmation of genetic disorders, facilitate management, accurate recurrence rissk, reproductive options (prenatal diagnosis, preimplantation genetic diagnosis), test for at risk relatives

Question 10

What diseases can be diagnosed with single gene testing and describe its symptoms

Answer 10

Achondroplasia (FGFR3)-skeletal dysplasia, disproportionaly short limbs+large head circumference
Duchenne&Becker muscular dystrophy-both same gene but Becker better prognosis

Question 11

What does genetic diagnosis help with

Answer 11

Confirmation of clinical diagnosis
reduces need for other investigations
may help prognostication
Recurrence risk
Informed choice in future prengancies
Presymptomatic testing
gene based therapiess

Question 12

What kind of risk figures does genetic counselling provide

Answer 12

risk figure for adult onset condition, offspring risk, family members’ risk

Question 13

What is required for accurate estimation of risk

Answer 13

confirmation of the diagnosis, accurate family tree

Question 14

Hardy weinberg rules

Answer 14

p+q=1

p^2+q^2+2pq=1