PATH 161 - Congenital and Genetic Disorders

Question 1

Chromosomes

Answer 1

• each cell contains 22 pairs of autosomes
• 1 pair of sex chromosomes
• genetic code of living cells

Question 2

Mitosis

Answer 2

• cell reproduction resulting in 2 daughter
  cells with the same DNA as parent cell
• parent cell and daughter cells contain 46
  chromosomes

Question 3

Meiosis

Answer 3

• special method of cell division where each
  daughter cell receives half the # of
  chromosomes (23 chromosomes)

Question 4

Karyotype 染色體組型

Answer 4

chromosomes arranged by size and shape

Question 5

Gene

Answer 5

• length of DNA, inherited from a parent
• controls all physical characteristics and
  metabolic processes of the cell
• found at a specific location on a chromosome

Question 6

Genotype 基因型

Answer 6

Entire genetic makeup of an individual

Question 7

Alleles 對立形質

Answer 7

Alternate forms of a gene
A gene’s matching function
- homozygous 同型結合的, 純合子的
- heterozygous 雜合的

Question 8

Homozygous

Answer 8

same on both chromosomes

Question 9

Heterozygous

Answer 9

different on both chromosomes

Question 10

Mutation

Answer 10

• error in process of cell replication
• may be spontaneous
• may result from exposure to harmful
  substance
  ie. radiation, drugs

Question 11

Phenotype 顯型

Answer 11

expression or effect of a gene

Question 12

Congenital defects

先天的缺陷

Answer 12

• disorders present a birth
• include genetic (inherited) disorders
• include developmental disorders
  (due to something which occurs during
  pregnancy)

Question 13

Single-Gene disorders
Inheritance Patterns
遺傳

Answer 13

• whether gene is carried on an autosome or
  sex (x) chromosome
• whether gene (allele) is dominant or
  recessive

Question 14

Dominant

Answer 14

allele that will always be expressed in a heterozygous individual.

Question 15

Recessive

Answer 15

traits that will only be expressed in a homozygous condition

Question 16

Single-Gene Disorders
Punnett Square
(田字框, 計算可能性-probability)

Answer 16

- statistical predictions for outcome of
  pregnancy
- pattern of inheritance
  (ie. gene / allele = dominant or recessive)
- parents' genotypes 基因型
  (do they have or carry the gene for this    
   trait or disease)
- autosomal recessive inheritance
- autosomal dominant inheritance
- x-linked recessive inheritance

Question 17

Autosomal Dominant Disorder

• adult polycystic 多囊的kidney disease
• Huntington’s chorea 舞蹈病
• familial hypercholesterolemia 血膽脂醇過多
• marfan’s syndrome

Answer 17

• 當病患呈現dominant 時會是兩個大寫
• 健康者normal 則會是兩個小寫
• carrier 則是一個大寫跟一個小寫

affected / carrier = heterozygous 雜合的
normal = homozygous
(same on both chromosomes)

Question 18

Autosomal Recessive Inheritance

• Cystic Fibrosis
• Phenylketonuria
• Sickle cell anemia
• Tay-Sachs disease

Answer 18

• 當病患呈現recessive 時會是兩個小寫
• 健康者normal 則會是兩個大寫
• carrier 則是一個大寫跟一個小寫

heterozygous = 雜合的

Question 19

X-Linked Recessive Inheritance
- Color blindness
- Duchenne muscular dystrophy 
  迪謝內肌營養不良
- Hemophilia A 血友病

Answer 19

• 孩子有分男女生
• 媽媽是兩個 XX
• 爸爸是一個 X 跟一個 Y
• 如果是recessive inheritance / disorder 時
  病患會是兩個小寫
  健康者normal 則會是兩個大寫
  carrier 則是一個大寫跟一個小寫
• 爸爸的 Y chromosome 永遠都不會有 trait
• 假設媽媽是 carrier, 爸爸是健康者
  媽媽 = XD, Xd / 爸爸 = XD, Y
• 假設媽媽是 carrier, 爸爸是病患
  媽媽 = XD, Xd / 爸爸 = Xd, Y
• heterozygous = 雜合的

Question 20

Chromosomal Disorder

- Numerical Abnormalities

Answer 20

occur when parts of chromosomes are rearranged or lost during replication
人體染色體數字不正確 正常都是兩個一對
Numerical Abnormalities 分為兩列:
1. Autosomes 正染色體
- Trisomy 21 (三(染色)體細胞)
   3 chromosomes rather than two in the 21
   position 
   ie. Down's Syndrome

2. Sex Chromosomes
   - Monosomy (單體性(染色體))
   occurs when only 1 sex chromosome (X) is
   present.
   ie. Turner Syndrome
   Klinefelter syndrome

Question 21

Turner Syndrome

Answer 21

• Example of Chromosomal Abnormality
• only have 1 copy of sex chromosomes
• has only 45 chromosomes (少一個)
• 45, X0
• result in physical abnormalities and lock of
  ovaries
• short stature
• neck: short and webbed
• swollen hands and feet
• wide chest, broadly-spaced nipples

Question 22

Klinefelter Syndrome

又稱為Polysomy X 多體性

Answer 22

• Example of Chromosomal Abnormality
• have 1 extra X chromosomes
  instead of XY 變成了XXY
• total of 47 chromosomes in each cell (多1個)
• result in small testes and sperm are not
  produced
• very tall, effeminate
• breats may be enlarged

Question 23

Down Syndrome

Answer 23

• Example of Chromosomal Abnormality
• Trisomy 21
• result in defects in physical and mental
  development

Question 24

Down Syndrome

Risks

Answer 24

• high risk of developing leukemia
• increase developing Alzheimer’s disease after
  40 y.o.

Question 25

Down Syndrome | Effects

Answer 25

- developmental stages are delayed - sexual development is delayed or incomplete - cognitively impaired (but severity varies with the individual) - visual problems - hearing problems - obstructions in the digestive tract - celiac 腹腔的 disease - congenital heart defect - decrease resistance to infection (immune deficit)

Question 26

Down Syndrome | Physical Characteristics

Answer 26

- head is small and has a flat facial profile - eyes are slanted 傾斜 and irises contain Brushfield spots - mouth tends to hang open and large protruding 突出的 tongue - hands are small and plamar crease 折縫 - muscles tend to be hypotonic - joints are loose - small ears and flat occiput 後頭部 - wide space btn 1st and 2nd toes

Question 27

Chromosomal Disorder | - Structural Abnormalities

Answer 27

``` - possible 4 types of structural abnormalities can occur - deletion - duplication - translocation - inversion ```

Question 28

Structural Abnormalities | Deletion

Answer 28

- genetic material - occurs when a part of chromosome is lost from the end of chromosome or btn 2 breaks within the chromosome - this material is usually lost

Question 29

Structural Abnormalities | Duplication

Answer 29

- genetic material - occurs when both chromosomes of a homologous pair 異體同型的 exchange unequal pieces of chromosomes - result in repeat of some info on 1 chromosome

Question 30

Structural Abnormalities | Translocation

Answer 30

- genetic material - occurs when chromosomes of non - homologous pairs exchange or transfer, pieces of chromosome - 2 types of translocation: 1. reciprocal translocation both chromosomes exchange parts 2. simple translocation 1 chromosome transfers a part of itself to a non-homologous chromosome

Question 31

Structural Abnormalities (Inversion) (染色體的)倒位

Answer 31

- genetic material - occurs when a chromosome has broken into 2 places and the info btn the breaks becomes inverted before it is reinserted 重新插入

Question 32

Multifactorial Disorders 多因子的 (Definition)

Answer 32

``` - combination of genetic influences and environmental factors - inherited tendency toward a disorder - it is expressed following exposure to certain environmental factors ```

Question 33

Multifactorial Disorders | Examples

Answer 33

- congenital dislocation of hip - cleft lip 兔唇 / cleft palate 裂齶 - clubfoot 畸形足 - pyloric stenosis 幽門狹窄 - hypertension - CAD - type 2 diabetes - some cancers (breast, colon)

Question 34

Developmental Disorders | Definition

Answer 34

caused by damage to one or more body structures during: - embryonic of fetal development - labor and delivery - shortly after birth

Question 35

Developmental Disorders | Causes

Answer 35

- spontaneous - intrauterine 胚胎時期的 environment examples: 1. maternal nutrition / disease 2. exposure to teratogens 畸胎 - difficulties during labor & delivery and neonatal 初生的 period example: cerebral palsy 癱瘓 due to hypoxia 氧不足 bilirubin toxicity, or trauma

Question 36

Purposes of genetic screening

Answer 36

- Reduces incidence of disease - offers reassurance and guidance to individuals or families

Question 37

Recommendations for Screening

Answer 37

- family / ethnic history of specific disease - previously given birth to a child with an abnormality - advanced maternal age

Question 38

Common Diagnostic Tools / tests | For Genetic Screening

Answer 38

- Pelvic Ultrasonography (obstetrics 產科學) - Chromosome Karyotype - Genetic Testing - Alpha-Fetoprotein (AFP) - Amniocentesis - Chorionic Villus Sampling (CVS) - Fetoscopy - Neonatal testing (ie. PKU, hypothyroidism)