Genetic Diseases

Question 1

Trisomy 21: Down Syndrome

Answer 1

Heart: Mitral valve prolapse, malformations of venous inflow, atrial or septal defects
Duodenum: Atresia
Enlarged tongue, open mouth, narrow palate
15x increased risk of leukaemia

Question 2

Trisomy 18: Edward’s Syndrome

Answer 2

Micrognathia

Rocker bottom feet

Question 3

Trisomy 13: Patau’s Syndrome

Answer 3

Cleft lip and palate

Rocker bottom feet

Question 4

Triple test

Answer 4

For diagnosis of trisomy 21
Alpha-fetoprotein down
Unconjugated estriol down
Human chorionic gonadotropin up

Question 5

Turner’s Syndrome

Answer 5

Female with only 1 X
Primary infertility
Short neck with net webbing
Genitalia is not well developed

Question 6

Klinefelter Syndrome

Answer 6

Male with extra X, the effects of testosterone are depressed
Feminization features
Treatable

Question 7

Fragile X syndrome

Answer 7

Amplification of CGG repeats

Long face and prominent ears

Question 8

Huntington’s Disease

Answer 8

Defect is on Chromosome 4
Behaviour changes
Abnormal and unusual movements
Dementia that slowly gets worse
-affects neural development because of the misfolding of the huntington gene
Disease develops with lesser amount of repeats than in Fragile X

Question 9

Prader Willi Syndrome

Answer 9

Paternal gene deletion/Maternal disomy
Male portion is imprinted and silenced
Hypotonic muscles
Obesity

Question 10

Angelman Syndrome

Answer 10

Maternal gene deletion/Paternal disomy
Maternal portion is imprinted and silenced
“Happy Puppet Syndrome”
Hypertonic muscles- ataxia

Question 11

Marfan Syndrome

Answer 11

Autosomal dominant
Defective fibrillin
Cardio: Mitral valve prolapse, weak aorta (dissecting aneurysm)
Skeleton: Very tall and lean
Eyes: Nearsighted, dislocated lenses
Palate deformity

Question 12

Ehlers Danlos Syndrome

Answer 12

Faulty collagen
Group of disorder- 6 major types
Autosomal dominant, some recessive
Joint pain and arthritis
Hyperflexibility/hypermobility- joint dislocation because not supported properly
Soft "velvety" skin with hyper extensibility, bruises easily, slow and poor wound healing that causes severe scaring 
Blue sclera
Periodontitis

Question 13

Familial Hypercholesterolemia

Answer 13

Autosomal recessive
Mutatino for LDL receptor on hepatocytes
LDL accumulates in plasma- promotes atherosclerosis, can give rise to periodontitis

Question 14

Cystic Fibrosis

Answer 14

Most common lethal gene in whites
Defect in cystic fibrosis transmembrane conductance regulator (CFTR), gene on chromosome 7
-Increased mucous viscosity, allows bacteria to thrive
-Salty hypertonic sweat with high chloride, used for diagnosis
-Pancreatic duct plugging and destruction of pancreas, can lead to malabsoprtion of some vitamins that require pancreatic secretions
Prone to nasal polys (involves the dysfunctional mucous?)
Lung infections cause most of the deaths

Question 15

Alkaptonuira

Answer 15

Lack of homogentistate 1,2-dioxygenase
Build up of homogentisic acid (HGA)
Manifests after 30 years of age
HGA in the urine
Urine to turn dark upon standing
Bluish-black pigmentation in connective tissue
Arthritis of spine and larger joints

Question 16

Phenylketonuria

Answer 16

Lack phenylalanine hydroxyls
Plasma phenylalanine accumulates
Brain damage

Question 17

Von Gierkes Disease

Answer 17

Glucose-6-phosphatase deficiency
Hepatic form of glycogen storage disease
Unable to liberate the glycogen stored in liver
Liver becomes enlarged
Hypoglycemia- failure to supply glucose

Question 18

McArdle’s Disease

Answer 18

Muscle phosphorylase missing
Myopathic (muscle) form of glycogen storage disease
Unable to liberate glycogen stored in striated muscle
Muscles are weak and cramp on exercise

Question 19

Pompe’s Disease

Answer 19

1,4-Glucosidase deficiency
Both muscle and liver unable to liberate glycogen as this enzyme is required in both
Lethal, death usually by age 2- common cause is heart failure as even the cardiac muscle becomes affected
Hepatomegaly
Muscular weakness

Question 20

Niemann-Pick Disease: Lysosomal storage disease

Answer 20

Deficiency in sphingomyelinase
Sphingomyelin accumulates- macrophages, neurons become foamy
Spleen and bone marrow affected especially
Death by age 5

Question 21

Gaucher Disease: Lysosomal storage disease

Answer 21

Defective glucocerebrosidase
Glucocerebrosidase accumulates- foamy phagocytes in liver, spleen, bone marrow, brain
Specialized symptom= bone damage, bone marrow is replaced with Gaucher cells

Question 22

Tay-Sachs Disease: Lysosomal storage disease

Answer 22

Defective hexosaminidase-a
GM2 ganglioside accumulates in neurons in CNS, PNS and retina
Limited to neural tissue
Specialized symtoms= blindness, seizures
Cherry red spot on retina allows early diagnosis

Question 23

Hurler Syndrome and Hunter Syndrome

Answer 23

Heparan sulphate and Dermatan sulphate storage
Mucopolysaccharidoses- defective degradation of mucopolysaccharide made by fibroblasts
Accumulation leads to coarsening of the skin and facial features
Also called gorgoylism
Shortened life- Hurler more severe