Clinical Genetics

Question 1

What are categories of genetic disorders?

Answer 1

Single gene disorder ( Mendelian inheritance)
Chromosomal disorder
Multifactorial

Question 2

Genetic causes of diseases

Answer 2

Down’s syndrome
Cystic fibrosis
Huntington’s disease
Haemophilia

Question 3

Multifactorial causes of disease

Answer 3

Spina bifida
Cleft palate
Diabetes
Schizophrenia

Question 4

Environmental causes of disease

Answer 4

Poor diet
Infection
Accidents
Drugs

Question 5

Clinical effects of cytogenetic abnormalities

Answer 5

Congenital abnormalities
Delayed development
Dysmorphic features
Small stature, microcephaly, failure to thrive
In adults - infertility still births miscarriage

Question 6

What is vertical transmission?

Answer 6

Vertical transmission: Passage of a disease-causing agent (pathogen) from mother to baby during the period immediately before and after birth.

Question 7

What is penetrance?

Answer 7

the extent to which a particular gene or set of genes is expressed in the phenotypes of individuals carrying it, measured by the proportion of carriers showing the characteristic phenotype.

Question 8

Example of autosomal dominant conditions

Answer 8

Adult polycystic kidney disease 
Familial hypercholesterolaemia
Marfan syndrome 
Huntington disease 
Familial breast and ovarian cancer

Question 9

Examples of AR conditions

Answer 9

CF 
phenylketonuria 
Haemochromatosis 
Spinal muscular atrophy
Non syndromic sensors neural deafness

Question 10

What is phenylketonuria

Answer 10

inborn error of metabolism that results in decreased metabolism of the amino acid phenylalanine. Untreated, PKU can lead to intellectual disability, seizures, behavioral problems, and mental disorders. It may also result in a musty smell and lighter skin

Question 11

Examples of X linked recessive conditions

Answer 11

Duchenne and Becker muscular dystrophy
Fragile x syndrome
Retinitis pigmentosa
Ocular albinism

Question 12

Examples of non Mendelian inheritance

Answer 12

Multifactorial
Imprinting
Mitochondrial inheritance
Mosaicism

Question 13

Neural tube defect is an example of what type of inheritance

Answer 13

Multifactorial inheritance

Question 14

What environmental factors contribute to neural tube defects

Answer 14

Folic acid

Maternal diabetes

Question 15

Explain mitochondrial disorders

Answer 15

Exclusively maternally inherited disease from those present in the cytoplasm of the ovum
Contains own circular 16.5Kb chromosome

Question 16

Examples of mitochondrial disorders

Answer 16

Mitochondrial encephalopathy lactic acidosis stroke like episodes
Myoclonic epilepsy ragged red fibres
Mitochondrially inherited DM and deafness
Leber’s hereditary optic atrophy

Question 17

What is genomic imprinting?

Answer 17

Genomic imprinting, process wherein a gene is differentially expressed depending on whether it has been inherited from the mother or from the father

Question 18

What are Prader-Willi and anglemans caused by

Answer 18

Cytogenic deletions of the same region of chromosome 15q or by uni parental display of chromosome 15

Question 19

What is the presentation of prader willi syndrome?

Answer 19

Neonatal hypotonia and poor feeding
Moderate mental retardation
Hyperphagia and obesity
Small genitalia

Question 20

What cause prader willi syndrome

Answer 20

Deletion in the paternally inherited chromosome 15 or maternal uniparental disomy

Question 21

What is the presentation of Angelman’s syndrome?

Answer 21

Happy puppet - unprovoked laughing clapping 
Microcephally
Mental retardation 
Seizures 
Ataxia
Broad based gait

Question 22

What causing angelman’s syndrome?

Answer 22

Caused by a deletion in the maternally inherited chromosome 15 or paternal uniparental disomy