1.  Multifactorial inheritance, also called complex or polygenic inheritance.
 Multifactorial inheritance disorders are caused by a combination of environmental
factors and mutations in multiple genes.
 For example, different genes that influence breast cancer susceptibility have been
found on chromosomes 6, 11, 13, 14, 15, 17, and 22.
 Some common chronic diseases are multifactorial disorders.
CHARACTERISTICS OF MULTIFACTORIAL DISEASE
 The disease can occur in isolation, with affected children born to unaffected
parents. Although familial aggregation is also common (i.e., there may be multiple
cases in the same family), there is no clear Mendelian pattern of inheritance.
 Environmental influences can increase or decrease the risk of the disease.
 The disease occurs more frequently in one gender than in the other, but it is not a
sex-limited trait. In addition, first-degree relatives of individuals belonging to the
more rarely affected gender have a higher risk of bearing the disease
 The concordance rates in monozygotic and dizygotic twins contradict Mendelian
proportions. A concordance rate is a measure of the rate at which both twins bear a
specific disease
 The disease occurs more frequently in a specific ethnic group
(i.e., Caucasians, Africans, Asians, Hispanics, etc.).

2. High Blood Pressure
-The cause of essential hypertension is multifactorial
 Genetic factors are thought to play a prominent role in the development
of essential hypertension.
 However, the genes for hypertension have not yet been identified
 Approximately 30% of cases of essential hypertension are attributable to
genetic factors.
 For example, in the United States, the incidence of high blood pressure is
greater among African Americans than among Caucasians or Asians.
Also, in individuals who have one or two parents with hypertension, high
blood pressure is twice as common as in the general population.
 The vast majority of patients with essential hypertension have in
common a particular abnormality of the arteries:
 an increased resistance (stiffness or lack of elasticity) in the tiny arteries
that are most distant from the heart (peripheral arteries or arterioles)

3. Others:
 Coronary Heart Disease
 Alzheimer's disease
 arthritis
 diabetes
 cancer
 Obesity
Multifactorial inheritance also is
associated with heritable traits such
as fingerprint patterns, height, eye
color, and skin color.

4.  Cytogenetics is an exciting, dynamic field of study which
analyzes the number and structure of human and animal
chromosomes.
 Changes that affect the number and/or structure of the
chromosomes can cause problems with
growth, development, and how the body functions.
 Chromosomal abnormalities can happen when egg and sperm
cells are being made, during early fetal development, or
after birth in any cell in the body
 Changes to chromosome structure can disrupt genes, causing
the proteins made from disrupted genes to be missing or
faulty. Depending on size, location, and timing,

5.  Cytogenetic analyses are commonly performed during pregnancy to
determine if a fetus is at risk for common aneuplodies
 Aneuplodies- syndromes caused by having extra or missing
chromosomes, syndromes caused by structural abnormalities (like
unbalanced translocations or inversions), or to determine if extra or
missing genetic material is present through cytogenetic microarray
testing.
 The same cytogenetic analyses can be performed on a newborn or child
with multiple anomalies or developmental delays to look for a potential
chromosomal abnormality
 Today, the diagnosis and treatment of several leukemias and
lymphomas, as well as some solid tumors, depends heavily on cytogenetic
analysis of specific chromosomal aberrations which are consistently
observed in these particular cancers.

6.  A single gene disorder is the result of a single mutated gene
 Over 4000 human diseases are caused by single gene defect
 Single gene disorders can be passed on to subsequent generations in several
ways. Genomic imprinting and uniparental disomy, however, may affect
inheritance p
Prevalence of some single gene disorders Disorder prevalence
(approximate)
 Autosomal dominant - Familial hypercholesterolemia 1 in 500, Polycystic
kidney disease 1 in 1250, Neurofibromatosis type I 1 in 2,500, Hereditary
spherocytosis 1 in 5,000, Marfan syndrome 1 in 4,000, Huntington's disease
1 in 15,000
 Autosomal recessive - Sickle cell anemia 1 in 625 Cystic fibrosis 1 in
2,000, Tay-Sachs disease 1 in 3,000, Phenylketonuria 1 in
12,000, Mucopolysaccharidoses 1 in 25,000, Lysosomal acid lipase deficiency
1 in 40,000,
Glycogen storage diseases1 in 50,000 Galactosemia 1 in 57,000
 X-linked- Duchenne muscular dystrophy 1 in 7,000, Hemophilia 1 in 10,000
Values are for liveborn infants atterns.

7. Autosomal dominant Only one mutated copy of the gene will be necessary for a
person to be affected by an autosomal dominant disorder.
Each affected person usually has one affected parent
Autosomal recessive Two copies of the gene must be mutated for a person to be
affected by an autosomal recessive disorder.
X-linked dominant X-linked dominant disorders are caused by mutations in
genes on the X chromosome
X-linked recessive X-linked recessive conditions are also caused by mutations in
genes on the X chromosome. Males are more frequently affected
than females, and the chance of passing on the disorder differs
between men and women.
Y-linked Y-linked disorders are caused by mutations on the Y
chromosome. Because males inherit a Y chromosome from their
fathers, every son of an affected father will be affected.
Because females only inherit an X chromosome from their
fathers, and never a Y chromosome, female offspring of affected
fathers are never affected.
Mitochondrial This type of inheritance, also known as maternal inheritance,
applies to genes in mitochondrial DNA. Because only egg cells
contribute mitochondria to the developing embryo, only mothers
can pass on mitochondrial conditions to their children.

8.  or Mendelian genetics or Mendelism or Monogenetic inheritance) is a scientific
theory of how hereditary characteristics are passed from parent organisms to
their offspring
MENDELS LAW
Law of Segregation The Law of Segregation states that every
(The "First Law") individual possesses a pair of alleles (assuming
diploidy) for any particular trait and that each
parent passes a randomly selected copy
(allele) of only one of these to its offspring.
The offspring then receives its own pair of
alleles for that trait.
Law of The Law of Independent Assortment, also
Independent known as "Inheritance Law", states that
Assortment (The separate genes for separate traits are passed
"Second Law") independently of one another from parents to
offspring

9.  Ability to taste
phenylthiocarbamide
(dominant)  Eyecolor
 Ability to smell (bitter  Morton's toe
almond-like) hydrogen  Tongue rolling
cyanide (recessive)
 Hair color
 Albinism (recessive)
 Brachydactyly  Widow's peak (allele)
(shortness of fingers  Detached (dominant)
and toes)
or attached
 Wet (dominant) or dry (recessive) earlobes
(recessive) earwax
 immunity to poison ivy  Hitchhiker's thumb
(dominant) (recessive)
EXAMPLES
Traits previously believed to be
Mendelian

10. CARDENAS, NORMA CZARINA M.
DMD-2D