Genetic Disorders

Question 1

Diversity of humans encoded in how much of our DNA?

Answer 1

0.5% (15 mil bp)

Question 2

Forms of DNA variations

Answer 2

SNPs & CNVs

Question 3

Types of DNA mutations

Answer 3

Point mutations (missense)
Nonsense mutations (stop codon)
Frameshift mutations
Trinucleotide repeat mutations

Question 4

miRNA actions

Answer 4

controls gene silencing

Question 5

Reduced/Incomplete penetrance

Answer 5

Seen in AD disorders

Have gene but no phenotype

Question 6

Variable expressivity

Answer 6

Seen in AD disorders

Have gene but differing extent of phenotype

Question 7

Huntington’s disease - onset, category

Answer 7

1 parent affected (Heterozygous)

Onset @ age 30-50

Question 8

Largest category of gene disorders

Answer 8

Autosomal recessive

Question 9

Sex-linked disorders appear on which chromosome?

Answer 9

X

Question 10

Lyonization

Answer 10

Using one X chromosome over another in female cells
Other chrom condenses into Barr body
Usually mosaic (different types of cells choose different chromosomes to use), but sometimes unfavorable

Question 11

Neurofibromatosis category

Answer 11

AD disease w/ variable expressivity

Question 12

Marfan syndrome - category, occurance, mutation of what

Answer 12

AD disorder, 1 : 5,000, Mutation of FBN1 - abnormal fibrillin

Question 13

Ehlers-Danlos - category, mutation of what

Answer 13

AD or AR, abnormal collagen synthesis

Question 14

Familial Hypercholesterolemia - category, occurance, mutation of what, risks

Answer 14

AD, 1 : 500, Inc. LDL in plasma, Heterozygous=2-3x increase & Homozygous=5x increase(die as teen via MI)

Question 15

Hereditary diseases that involve mutations in receptor proteins/channels

Answer 15

Familial Hypercholesterolemia

Cystic Fibrosis

Question 16

Hereditary diseases that involve mutations in enzyme proteins

Answer 16

Phenylketouria

Storage diseases

Question 17

Cystic fibrosis - mutation in what

Answer 17

Cl- channels, pseudomonas infxns, mucous plugs

Question 18

Phenylketouria (PKU) - category, occurance, mutation in what

Answer 18

AR, 1 : 10,000, Decreased phenylalanine hydroxylase -> hyperphenylalanemia + PKU

Question 19

Types of storage diseases

Answer 19

Lysosomal

Glycogen

Question 20

Lysosomal storage diseases

Answer 20

Tay-Sachs
Neimann-Pick
Gaucher
Mucopolysaccharidoses (Hurler & Hunter)

Question 21

Hurler disease - mutation in what

Answer 21

Lysosomal storage disease, decreased alpha-L-iduronidase (laronidase)

Question 22

Hunter syndrome - mutation in what, category

Answer 22

Lysosomal storage disease, decreased L-iduronate sulfatase, X-linked

Question 23

How often to newborns have chromosomal abnormalities?

Answer 23

1 : 200

Question 24

Frequency of inheritance of multifactorial disease

Answer 24

2-7%

Question 25

Euploid

Answer 25

2x23 = 46

Question 26

Polyploidy

Answer 26

3x23 or 4x23 (spontaneous abortion)

Question 27

Aneuploidy

Answer 27

Not an exact multiple of 23 (cancer)

Question 28

Trisomy

Answer 28

2x23+1 = 47 - Extra chromosome

Question 29

Monosomy

Answer 29

2x23-1 = 45 - Missing chromosome

Question 30

Translocation of chromosome

Answer 30

Transfer of part of 1 chrom to another (sometimes reciprocal)

Question 31

Deletion of chromosome

Answer 31

Loss of portion of chromosome (retinoblastoma)

Question 32

Inversion of chromosome

Answer 32

Chrom breaks & rearranges backward

Question 33

Trisomy 21 - occurance, clinical dental features

Answer 33

Mother 45 y.o. = 1 : 25

Inc. perio disease, large tongue, inc. acute leukemia

Question 34

Klinefelter - mutation in what, characteristics, dental features

Answer 34

XXY, XXYY - male hypogonadism(sterile), male phenotype, inc. taurodontism

Question 35

Turner - mutation in what, characteristics, features

Answer 35

X - No secondary sex char, high palate, cardiovascular malformations, short stature, shield chest

Question 36

When to recommend prenatal gene counseling

Answer 36

Mother > 34 y.o.
Carrier of chrom. translocation/ X-linked disorder
Hx of previous child w/ chromosomal abnormality

Question 37

When to recommend postnatal gene counseling

Answer 37

Multiple abnormalities
Development delay
Infertility
Multiple spontaneous abortions