11 HUMAN GENETICS Flashcards
1
Q
To determine the pattern of inheritance of man’s traits, the construction of family
history is performed.
A
pedigree analysis
2
Q
By doing pedigree analysis, one can determine the possible genotypes and phenotypes of the individuals, and can predict if the trait can be _____
A
possibly transmitted to the next generation
3
Q
The affected individual whom the pedigree is discussed is called the ____
if male, ____
if female, ____
A
proband
propositus
proposita
4
Q
Analyzing pedigrees can reveal?
A
(a) whether a trait is dominant or recessive
(b) the type of chromosome (autosomal or sex) to which the trait is linked
(c) genotypes of family members
(d) probabilities of phenotypes in future generations
5
Q
Generations (sometimes labeled with Roman numerals).
A
Rows
Top row-oldest generation
6
Q
Second individual of the first generation
A
I-2
(family members labeled numerically from left to right
7
Q
used to analyze the pattern of inheritance of a particular trait throughout a family
A
Pedigrees
8
Q
show the
presence or absence of a trait as it relates to the relationship among parents, offspring, and siblings.
A
Pedigrees
9
Q
By analyzing a pedigree, we can determine genotypes, identify phenotypes, and predict how a trait will be passed on in
the future.
The information from a pedigree makes it possible to determine how certain alleles are inherited: whether they ____
A
are dominant,
recessive,
autosomal, or
sex-linked.
10
Q
Determine whether the trait is dominant or recessive
If the trait is dominant, ____ of the parents must have the trait.
Dominant traits will not skip a generation.
A
one
11
Q
If the trait is recessive, neither parent is required to have the trait since they can be ____.
A
heterozygous
12
Q
Determine if the chart shows an autosomal or sex-linked
For example, in ____ traits, males are much more commonly affected than females.
A
X-linked recessive
13
Q
Determine if the chart shows an autosomal or sex-linked
In ____ traits, both males and females are equally likely to be affected (usually in equal proportions).
A
autosomal
14
Q
2 Common mistakes and misconceptions
A
- The presence of many affected individuals in a family does not always mean that the trait is dominant
- You may not always be able to determine the genotype of an individual based on a pedigree.
15
Q
5 Common pattern of inheritance in man
A
- autosomal recessive
- autosomal dominant
- sex-linked dominant
- sex-linked recessive
- sex-influenced
16
Q
The trait for this type of inheritance never skips a generation
A
autosomal dominance
17
Q
autosomal dominance Affected individual may either be
A
homozygous dominant or heterozygous
18
Q
Marriage between 2 affected individuals produce affected offspring
A
Autosomal recessive
19
Q
May also be produced by both unaffected person heterozygous for the character
A
autosomal recessive
20
Q
autosomal recessive example
A
inability to roll tongue
ankyloglossia or nerve disorder
21
Q
Affected male with unaffected wife transmit the trait to daughter only
A
Sex-linked dominance
22
Q
Sex-linked dominance example
A
defective teeth enamel
23
Q
Affected female with unaffected husband transmits the trait to sons only; the daughters serve as carrier of the trait
A
Sex-linked recessive
since male have only one X, they are already affected, but females have two so their other X can compensate: such as G6PD (both parents must be affected to produced an affected daughter)
24
Q
Sex-linked recessive example
A
colorblindness
hemophilia
25
Gene exhibits high penetrance or expressivity in one sex
sex-influenced
26
sex-influenced example
harelip, baldness (more frequent in men than in women);
spina bifida (forked spine with open spinal cord) - more frequent in women than in men.
27
7 Inheritance patterns
1. autosomal dominant
2. autosomal recessive
3. X-linked dominant
4. X-linked recessive
5. Y-linked
6. Co-dominant
7. Mitochondrial
28
One mutated copy of the gene in each cell is sufficient
for a person to be affected
autosomal dominant
29
autosomal dominant example
Huntington disease
Marfan syndrome
30
* both copies of the gene in each cell have mutations
* parents of an affected individual each carry one copy of the mutated gene
* typically do not show signs and symptoms
* not seen in every generation of an affected family.
autosomal recessive
## Footnote
between affected and unaffected
31
autosomal recessive example
Cystic fibrosis
Sickle cell disease
32
are caused by mutations in one of the two sex
chromosomes in each cell.
X-linked
dominant
33
# X-linked Dominant
In females, a mutation in ____ copies of the gene in each cell is sufficient to cause the disorder.
In males, a mutation in the ____ of the gene in each cell causes the disorder.
one of the two
only copy
## Footnote
Most cases, male have severe symptoms than females.
34
A characteristics of ____ is that fathers cannot pass ____ traits to their sons.
X-linked Inheritance
X-linked
## Footnote
this is because the X trait passed to offsprings are from mothers
35
male always affected pass to daughters
X-linked dominant
36
X-linked dominant example
Fragile X Syndrome
37
# X-linked recessive
In males, ____ mutation is sufficient to cause condition.
In females, a mutation would have to occur in ____ of the gene to cause the disorder.
one
both copies
## Footnote
Because it is unlikely that females will have two altered copies of this gene, males are affected more.
38
X-linked recessive example
hemophilia
39
Because only males have a Y
chromosome, in Y-linked inheritance, a mutation can
only be passed from ____
father to son.
40
Y-linked inheritance example
Y chromosome infertility
41
two different versions (alleles) of a gene are expressed, and each version makes a slightly different protein
Co-dominant
## Footnote
Both alleles influence
the genetic trait or determine the characteristics of the
genetic condition
42
Co-dominant example
ABO blood group
alpha-1 antitrypsin deficiency
43
applies to genes in mitochondrial DNA.
Mitochondria
mitochondrial inheritance
44
Conditions resulting from mutations in mitochondrial
DNA can appear in ____ of a family and can affect both males and females, but fathers do not pass these disorders to their daughters or sons
every generation
45
mitochondrial inheritance example
Leber hereditary optic neuropathy (LHON)
46
At least ____ of all spontaneous miscarriages result from gross chromosomal aberrations.
About ____ of spontaneous abortion and ____ of still births and newborn deaths are due to triploidy
25%
17%
3%
47
two classes of aneuploidy
autosomal aneuploidy
sexual aneuploidy
48
It has been found that around ____ of local clinically recognized pregnancies carry some
form of trisomy.
4%
49
Who first described DS in 1866?
British physician
J. Langdon Down
50
More than 80% of the children with DS are born from women under ____
35 years of age.
## Footnote
associated with maternal age
51
Triplo – 21 arises from non-disjunction of chromosome during ____.
oogenesis
52
a degenerative disorder of the human central nervous
system resulting in the progressive impairment of the memory
Alzheimer’s Disease (Ad)
## Footnote
related to Down syndrome since the genetic region for both disorders is found to be the **chromosome 21**
53
One feature of
AD is that they have numerous plaques in the ____.
____ protein is the main
component of this plaque.
cortical cell
Amyloid
## Footnote
The same protein with identical amino acid sequences is found in
the aged mongoloid. Deposition of amyloid protein is normal for aging individuals.
54
With multiple malformations;
Low- set ears, small lower jaw,
clenched fingers, deformed skull,
face, feet
With cardiac malformations
Displaced liver
Growth retardation
Severe mental retardation
Trisomy 18
Edward’s
syndrome
## Footnote
chromosome 16, 17, 18
55
with sloping forehead, harelip,
palate, deformed face
polydactyly present
markedly mental retarded
cardiac and internal defects
Trisomy 13
Patau
syndrome
## Footnote
chromosome 13, 14, 15
56
Mental Retardation; **slanting
eyes**; mongolian eye fold; saddle nose; swollen tongue;
underdeveloped ears; **slightly
flattened face**; with enlarged liver and spleen; broad and short skull; thick, short hands, feet and trunk; mentally retarded: **IQ is about 25-74**; with happy disposition in life; affectionate
Reproductive capacity:
Female – fertile; can produce ____ mongoloid offspring
Male- sterile
Trisomy -21
Down
Syndrome
520%
57
Who first described Edward's Syndrome?
John H. Edwards and his associates in 1960
58
Death generally take place at around ____ of age up
although there is one reported case in which the child reached the age of 15. The incidence of
ES is also found to be related to maternal age
3 to 4 months up to nearly two years
59
Who first described Patau Syndrome?
Klaus Patau
60
* **male phenotype** with normal external genitalia
* sparse pubic and facial hair
* rudimentary testes and prostate glands
* No spermatogenesis (not fertile)
* Longer arms and legs; large hands and feet
* **Enlarged breast**
* High-pitched voice
* Normal to slightly retarded socially inadequate, dependent, & submissive
Klinefelter’s
syndrome
61
Causes of Klinefelter’s
syndrome
XX female cross with Y male
X female cross with XY male
62
* General **female** phenotype **short** stature, **webbed** neck **broad** chests
* liittle or no development of 2° sex characteristics
* **No ovarian development**
* Abnormal hormonal secretions
* Slight mental retardation
Turner’s
syndrome
63
cause of Turner’s
syndrome
Absence of male x chromosome
(causes unknown)
64
* **Female** sex phenotype
* At 22, infantile external genitalia
* With **menstrual irregularities,** premature menopause
* Somewhat retarded
Triplo-X
syndrome
65
* **Exceptional height**
* With acne
* Speech and reading problems
* Aggressive and anti-social
Jacob
Syndrome or
Double Y
Syndrome
66
* Have **both ovarian and testicular tissues.**
* Congenital anomalies
* Mental retardation
Hermaphroditism
67
4 Human Disorders Due to Changes in Chromosome Structure
1. Cri-du-chat Syndrome (deletion)
2. Muscular dystrophy (deletion)
3. Robertsonian translocation
4. Philadelphia Syndrome
68
results from the deficiency of the short arm of chromosome ____, which is due to the translocation of B/G and B/D chromosome groups.
Cri-du-chat Syndrome (Deletion)
5
## Footnote
Features: severely mentally retarded; characteristic cat-like cry (small epiglottis and
larynx)
69
deletion of a small segment of
chromosome X, involving the genes for the synthesis of **dystrophin**
Muscular dystrophy (Deletion)
70
is
a complex of protein that work together to
strengthen muscle fibers and protect them
from injury as muscles contract and relax
Dystrophin
71
Muscular Dystrophy (deletion) results in either
a) no dystrophin synthesis due to frameshift mutation (**Duchenne Muscular Dystrophy** or DMD)
b) synthesis of smaller but partially functional dystrophin (**Becker Muscular Dystrophy** or BMD)
72
Reciprocal translocation involving chromosomes 2 and 20
Robertsonian translocation
| produce symptoms similar to Down syndrome and Patau syndrome
## Footnote
absence of bile ducts in the liver, abnormalities of the eyes and ribs, heart
defects and sever itching
73
translocation involving
chromosomes 9 and 22
Philadelphia syndrome
74
activates the oncogenes,
which converts a cell into
a tumor cell.
Philadelphia syndrome
75
PS results to ____, a fatal cancer
involving uncontrolled
replication of stem cells
of the **WBC**
chronic
myelogenous leukemia
(CML)
76
are rare genetic (inherited) disorders in which the body
cannot properly turn food into energy
Inborn error of metabolism
77
Who introduced Inborn error of metabolism
Archibald Garrod
78
Garrod postulated that some inherited disorders result from the ____ that are involved in biochemical pathways (Yudkoff, 2017). These specific
proteins (enzymes) help break down parts of food
lack or reduced
activity of enzymes
79
Examples of inborn errors of metabolism
albinism,
phenylketonuria (PKU),
sun sensitivity,
thyroid disease, and
galactosemia
80
____ is a component of lactose, which is not required in normal human development but can be used as energy source
Galactose
81
A condition characterized by accumulation by
galactose in the blood
Galactosemia
## Footnote
Symptoms include enlargement of the liver, slow growth, muscle weakness, cerebral palsy, seizures and mental retardation
82
____ are unable to metabolize galactose because of
deficiency in ____, resulting in the accumulation of galactose in the
blood
Homozygous recessive individuals (gg)
Gal-1-P uridyl transferase
83
An inborn error of metabolism that renders an individual unable to hydroxylate
phenylalanine to tyrosine
. Phenylketonuria (PKU)
## Footnote
lacks phenylalanine hydroxylase (PAH)
84
Phenylalanine is converted into ____, which may inhibit the conversion
of tryptophan into serotonin
phenylpyruvic acid
85
Four Basic Phenotypes of PKU:
1. PKU with profound mental retardation
2. Moderate PKU
3. Mild PKU
4. Simply excreting excess amino acid in urine
86
PKU follows the ____ pattern of inheritance, in which both the father
and the mother possess and pass the defective gene to a child
autosomal recessive
87
What are the risk factors for inheriting PKU?
a) Having two parent carrying the defective gene for PKU
b) Being of certain ethnic descent. The gene defect that causes PKU is less common in
African-Americans than in other ethnic groups.
88
____ is a hereditary abnormality that is due to errors on melanin synthesis.
Albinism
89
It is
characterized by _____ pigment due to errors in the
production of melanin from tyrosine
congenital reduction or absence of melanin
90
In order to detect early these inborn errors abnormalities and to implement measures to
address the health effects of these abnormalities, _____ can be employed.
newborn screening
91
____ is a comprehensive policy or nation system for ensuring
Newborn Screening.
RA 9288 (Newborn Screening Act)
## Footnote
ideally done 24 hours from birth, using the **heel prick method.**
92
4 disorders that can be detected using newborn screening
1. Congenital Hypothyroidism (CH)
2. Galactosemia (GAL)
3. Phenylketonuria (PKU)
4. Glucose-6-Phosphate Dehydrogenase deficiency
93
It is due to the lack of thyroid hormone. It may affect
the physical growth of the baby and may suffer from mental retardation.
Congenital Hypothyroidism (CH)
94
. In this case, the body lacks
the enzyme G6PD, resulting to ____
haemolytic anemia.
95
Group of disorders that affect hemoglobin
Sickle Cell Disease
96
– in heterozygous condition may have no effect but may be expressed when mating occurs
between carriers
## Footnote
example?
Recessive lethal
## Footnote
sickle cell anemia
Features: low number of RBC (anemia), repeated infections, and periodic episodes of pain.
97
examples of behavior that are found to be heritable
schizophrenia
eating disorders
drug addiction
mood disorders
intelligence
98
* Characterized by cleavage of personality, and loss of ability to organize thoughts and perception.
* Has delusions and hallucinations
* Onset on the 3rd decade of life
* 1% of the world’s populations; 17-27 y/o males, 20-37 y/o females
* genes found on ____ different chromosomes
Schizophrenia
14
99
Eating disorders can be in the form of
anorexia or bulimia.
100
perceives self as obese and starves intentionally; death risk of 15 to 21%
Anorexia nervosa
101
characterized by eating huge amounts to be followed
by vigorous and vomiting in order to maintain weight
Bulimia
102
males see themselves as
too small and takes amino acid supplements to have masculine
physique
Muscle dysmorphia or bigorexia
103
Eating disorders arecaused by:
1. high risk genes controlling traits such as **perfectionism**, orderliness, etc.
2. genes for proteins that control **appetite**
3. genes that regulates the **dopamine** and **serotonin**
104
Anorexia genetic linkage on chromosome ____
* not due to a single gene, but a number of genes that dispose someone to it
* These genes may include those associated with anxiety, perfectionism or perseverance,
or for hormonal, metabolic and appetite factors
1
105
High heritability (**40-60%**)
characterized by compulsive behavior of seeking and taking a drug despite of its known
adverse effects
Changes in the limbic system to **addiction**
Drug addiction
106
more
common in women; chronic depression
interspersed with acute episodes. It is likely
due to deficiency in neurotransmitters
serotonin or norepinephrine.
Major depressive disorders (MDD)
107
2 Mood disorders
* MDD
* Bipolar effective disorders or manic-depression: weeks or months of depression
alternate w/ periods of mania
108
NT believed to help regulate
mood and social behavior, appetite
and digestion, sleep, memory, and
sexual desire and function
serotonin
109
Genes involved in MD are located on chromosomes ____ and ____
4, 10, 18 and 22 and mitochondrial DNA
110
foundation of rational behavior
not a well-defined characteristic
intelligence
111
the best and most usable measure of intelligence
Intelligence Quotient (IQ) ratings
112
____ does not play a major role in IQ differences
Environment
113
a candidate gene for intelligence
Neural cellular adhesion molecule (N-CAM)
114
Chromosome ____ contains intelligence related genes
4
115
IQ was devised by?
1969, Jensen’s hypothesis:
**I.Q. is largely hereditary**
## Footnote
was supported by
Hernstein in 1971
116
At present, it is
known that I.Q. is ____ hereditary, and
the remaining ____ is due to the
influence of the environment
80%
20%
117
____ is a series of tests that measure verbal fluency, mathematical reasoning, memory and spatial visualization ability.
IQ test
118
Studies showed that more
alcoholics are ____
color blind.
119
Alcoholism is
an____ trait
X-linked recessive
120
In a study on
mouse, ____ are found in
the brain of alcoholic mice and absent in
would be non-drinkers.
phenolic compounds
121
IN addition, scientists found that
alcohol dependence might be associated
with up to ____ in different regions
of the chromosome.
51 genes
## Footnote
others contribute to
alcohol dependence such as
environmental, social, and psychological
factors
122
A behavioral disorder that can
be strongly inherited
Criminality
123
Result of studies showed that the
criminal tendency of identical
twins have very strong
similarities (____), while it is only about ____ for the fraternal twins.
70%
28%
124
Ramirez (1991), however, mentioned that what is being inherited is not the
predisposition to criminality but the ____
tendency to **react in the same manner to similar stimuli**.
