Genetics Exam 2 Material

Front 1

Aneuploidy is generally caused by...

Back 1

Maternal Non Disjunction

Front 2

What are symptoms of down's syndrome?

Back 2

hypotonia, rounded head with 3rd fontanelle, flat nasal bridge, protruding tongue, epicantric folds in eyes, single palmer crease in hands, congenital heart defects, 15-20% increased risk for having leukemia, increased risk for Alzheimer’s disease

Front 3

What are the causes of Down's syndrome?

Back 3

95% meiotic nondisjunction; 4% Robertsonian Translocation; 1% mitotic nondisjunction (higher functioning) – some cells are 46 chromosomes, some are 47 = mosaicism

Front 4

What is Edward's syndrome?

Back 4

Trisomy 18

Front 5

What are the clinical features of Edward's syndrome?

Back 5

reduced birth weight, hypertonia, distinctive hands (clenched and overlapping digits), rocker bottom feet, facial malformations (recessed chin/jaw, low set malformed ears, malformed heart, prominent occiput)

Front 6

What trisomy is Patau's Syndrome?

Back 6

Trisomy 13

Front 7

What are the clinical features of Patau's syndrome?

Back 7

CNS malformations, presence of single forebrain hemisphere/lobe, cleft lip/palate, microphtalmia – often blind, polydactyl, also has rocker bottom feet and clenched fist like Edward’s

Front 8

What is a Robertsonian Translocation?

Back 8

Fusion of long arms of 2 acrocentric chromosomes

Front 9

What are the common chromosomes associated with Robertsonian Translocation?

Back 9

Chromosomes 13, 14, 15, 21, 22 – 13q14q and 14q21q are common

Front 10

What cannot Array Comparative Genomic Hybridization detect?

Back 10

Cannot detect inversions or balanced rearrangements

Front 11

What is the usual cause of Sex Chromosome Disorders?

Back 11

Paternal Non Disjunction in Meiosis II

Front 12

What are clinical features of Klinefleter's XXY?

Back 12

tall, thin, long legs; at puberty – hypogonadism, underdeveloped secondary sex characteristic, gynecomastial (development of mammy gland), infertile, decrease verbal comprehension and ability

Front 13

What are the clinical features of Turner's Syndrome?

Back 13

webbed neck, lymphedema of hands and feet, short stature, infertile, severe cognition skills but IQ is average or above, deficiency in spatial perception and fine motor skills

Front 14

What's the treatment for Turner's syndrom?

Back 14

growth hormones and estrogen

Front 15

What is Camptomelic Dysplasia?

Back 15

Autosomal dominant disorder with lethal bone/cartilage malformations

Front 16

How can you be an XY female?

Back 16

Delete SRY
2 copies of DAX 1
1 copy of SOX 9

Front 17

How can you be an XX male?

Back 17

Presence of SRY on X due to recombination
2 copies of SOX 9 - an overproduction of SOX 9 causes a suppression of SRY

Front 18

What is the most common defect in Congenital Adrenal Hyperplasia?

Back 18

Deficiency in 21 Hydroxylase - necessary for cortisol production.

Front 19

What are the causes for Male Pseudohermaphroditism?

Back 19

Deficiency 5-alpha reductase, Androgen Insensitivity Syndrome

Front 20

What are Paralogs?

Back 20

Genes expressed in the same region of the body such as A13 and D13

Front 21

What 3 HOX Genes mutations have been Identified?

Back 21

A1, A13, D13

Front 22

What are the phenotypes for A1 mutation?

Back 22

horizontal gaze and deafness, variable facial weakness, hypoventilation, vascular malformations, autism, no abducens cranial nerve and absence of inner ear structure

Front 23

What are the clinical features of a Sonic Headhog Mutation?

Back 23

Holoprosencephaly – failure of midface/forebrain to develop, single forebrain hemisphere, cleft lip/palate, hypotelorism (eyes close together)

Front 24

What is mutated in Type I and III of Wardenburg Shah Syndrome?

Back 24

PAX3

Front 25

Which form is the milder form of Wardenburg Shah Syndrome and what gene does it affect

Back 25

Type II - MITF

Front 26

What happens in a mutation of PAX 6?

Back 26

Aniridia = absense of iris

Front 27

What causes Rubenstein-Taybi Syndrome?

Back 27

Mutations in CBP, Can't Bind CREB, can't activate transcription

Front 28

What is the Phenotype of Rubenstein-Taybi?

Back 28

mental retardation, broad thumbs/toes, hirsutism (excessive hair), cryptoorhidism (undescended testes), congenital heart defects, downslanting palpebral fissure, hypoplastic maxilla, prominent nose

Front 29

What is a LOD Score?

Back 29

Z=log10 (likelihood data are linked at a given theta/likelihood data are unlinked, theta=.5)

Front 30

What are the significant values for LOD scores?

Back 30

Positive Z = suggestive of linkage
Z > 3 : 2 loci are linked
Z<-2 : 2 loci are unlinked

Front 31

What is the mutation in sickle cell anemia?

Back 31

mutation in Beta chain gene, Glutamine is changed to Valine, lose a restrictive enzyme site

Front 32

What is the problem with blood transfusion for people with Sickle Cell Anemia?

Back 32

Iron Overload

Front 33

What are thalassemias?

Back 33

decrease rate of synthesis/stability of one or more Hb Chains leading to imbalance in relative amounts of alpha and beta chain

Front 34

What is the phenotype of some one with PKU?

Back 34

mental retardation, eczema, hypopigmentation

Front 35

What are the 3 types of PKU?

Back 35

PKU, variant PKU and Non-PKU hyperphenylalanemia

Front 36

What was the most common underlying deficiency in children that had SIDS?

Back 36

MCAD - Fatty acid Disorder

Front 37

What is deficient in Tay-Sachs?

Back 37

hexosaminadase A

Front 38

What disorder is related to Cherry Red Spot?

Back 38

Tay-Sachs

Front 39

What are the symptoms of Cystic Fibrosis?

Back 39

malodorous stools, colic, “salty baby” chronic cough, frequent upper respiratory tract infections

Front 40

What is the test for CF?

Back 40

sweat chloride level. Normal 20mmol/L, CF = 75mmol/L

Front 41

What is Osteogenesis Imperfecta?

Back 41

brittle bone disease” - Problems with ossification; inherited disorder of type I collagen with wider range of clinical heterogeneity from lethal form to increase in fracture frequency

Front 42

List the types of OI in order from mildest to most severe

Back 42

Type I is mildest (usually loss of 1 chain) followed by III/IV and II is most devastating

Front 43

What is the repeating unit is a collagen chain?

Back 43

(Gly-X-Y), X is usually proline, and Y is hydroxyproline/hydroxylysine

Front 44

What is gene is mutated with Marfan's Syndrome?

Back 44

Fibrillin 1

Front 45

How do people with Marfan's Syndrome usually die?

Back 45

Cardiovascular Problems

Front 46

95% of Acondroplasiacs is due to what receptor?

Back 46

G380R

Front 47

What is one of the largest genes in the X chromosome?

Back 47

Dystrophin

Front 48

Why do people with hemophilia bleed a lot?

Back 48

Factors 8 and 9 play a role in converting prothrombin to thrombin which is involved in the final step in converting fibrinogen  fibrin. Can’t create fibrin clot

Front 49

What enzyme is related to Fava Beans and what does this enzyme do?

Back 49

This is the 1st enzyme in hexose monophophate shunt that generates NADPH which detoxifies oxidants by generating reduced glutathione

Front 50

What is the deficiency in Lesch Nyan Syndrome?

Back 50

Deficiency in hypoxanthing guanine phosphoriboxyl transferase (HPRT) which is used as a feedback enzyme to shutdown puring production like adenosine and guanine

Front 51

What is genetic anticipation?

Back 51

As genes are passed down:
Age of onset of disorder decreases
Severity increases
Incidence of disease increases

Front 52

What happens in Fragile X? As in what is the gene? Where is it located? And what does this cause?

Back 52

Fragile X mental retardation gene 1 – FMR1, CGG repeat in 5’ UTR
Hypermethlation causes transcriptional silencing, closed chromatin, RNA polymerase cannot access gene, no FMR1 made

Front 53

What repeat causes Huntington's Disease?

Back 53

CAG

Front 54

Why are the symptoms of Myotonic Dysplasia?

Back 54

muscle hypoplasia, severe mental retardation, moderate facial weakness, myotonia, cataracts