close

Вход

Забыли?

вход по аккаунту

?

Genetics

код для вставкиСкачать
Genetics
U.K. College of
Nursing
Genes and
Chromosomes
пЃєEach cell contains 23 pairs of
matched chromosomes for a
total of 46 chromosomes per
cell.
пЃєOne chromosome from each
pair is inherited from each
parent.
пЃєThere are 22 pairs of
autosomes, which control most
traits in the body, and one pair
of sex chromosomes, which
determine gender and other
traits.
Genes and
Chromosomes
пЃєSome genes are dominant and
their characteristics are
expressed even if only on one
chromosome.
пЃєSome genes are recessive and
their characteristics will be
expressed only if they are
carried by both chromosomes
in a pair.
Group Exercise
Human Variation
Punnet Squares
пЃєVisual representation of the
principles of inheritance
пЃєDominant trait--Capital letter
пЃєRecessive trait--Small letter
пЃєMale vs female trait/gene
Patterns of
Inheritance
пЃєAutosomal Dominant
пЃєAutosomal Recessive
пЃєSex-Linked (or X-linked)
Dominant
пЃєSex-Linked (or X-linked)
Recessive
пЃєChromosomal Abnormalities
пЃєCongenital Anomalies
Autosomal
Dominant
пЃєTrait appears in every
generation (does not skip)
пЃєBoth males and females are
affected
пЃєEach pregnancy of an affected
person has a 50% chance of
producing an affected
offspring
Autosomal
Dominant Disorders
пЃєDisorders
Huntington’s Disease
пЃ№Retinitis Pigmentosa
пЃ№Polycystic Kidney Disease
пЃ№Achodroplasia
пЃ№Marfan Syndrome
Dominant
Disorders- Marfan
Syndrome
Autosomal Dominant Inheritance
Autosomal
Dominant
пЃєClinical Situation-пЃ№One parent is unaffected
пЃ№One parent carries the defective
gene for Marfan Syndrome
пЃєDraw the Punnet Square
Autosomal
Dominant Punnett
Square
Autosomal
Recessive
пЃєBoth parents are usually
unaffected, but are carriers
пЃєTrait first appears only in
siblings rather than in parents
пЃє Trait found equally in males
and females
пЃє25% risk when both parents
are carriers
пЃєIncreased incidence with
consanguinity
Autosomal
Recessive
пЃєDisorders
пЃ№Phenylketonuria
Fanconi’s Anemia
пЃ№Tay Sachs Disease
пЃ№Sickle Cell Anemia
пЃ№Cystic Fibrosis
Autosomal Recessive Inheritance
Autosomal
Recessive
пЃєClinical Situation
пЃ№Male carries the defective gene
for Tay Sachs disease
пЃ№Female carries the defective
gene for Tay Sachs disease
пЃєDraw the Punnett Square
Autosomal
Recessive Punnett
Square
X-linked Inheritance
пЃєSex-Modified Traits - Dominant
genes are expressed in both
males & females but at
differing frequencies
пЃ№Ex: Baldness - expressed as
dominant in males, but recessive
in females, never as severe in
females
X-linked Dominant
пЃєVery rare
пЃєOften lethal in males therefore
few males present in the
pedigree
пЃєMultiple miscarriages may be
present
пЃєNo carrier status, all
individuals with the gene are
affected
пЃєTrait appears in every
generation
X-linked Dominant
пЃєFemale children of affected males
will all be affected (100% risk); no
male to male transmission.
пЃєHomozygous females (both X
chromosomes are affected) have a
100% chance of having an affected
child of either sex.
пЃєHeterozygous females (only one X
affected) have a 50% of having an
affected child with each pregnancy.
X-linked Dominant
Disorders
пЃєHypophosphatemic Rickets
пЃєFragile X Syndrome
Fragile X Syndrome
X-linked Dominant
пЃєClinical Situation
пЃ№Male is affected with
hypophosphatemic rickets
пЃ№Female is unaffected
пЃєDraw the Punnet square
X-linked Dominant
Punnet Square
X-linked Recessive
пЃєIncidence of trait much higher
among males in a kinship than
among females
пЃєTrait cannot be transmitted from
father to son
пЃєAn affected male will pass the
carrier status to all his daughters
пЃєFemale carriers have a 50% risk of
transmitting the gene to their
offspring with each pregnancy
X-linked Recessive
пЃєDisorders
пЃ№Hemophilia A
Duchenne’s Muscular Dystrophy
пЃ№Color-Blindness
Duscenne’s
Muscular Dystrophy
X-Linked Recessive Inheritance
X-linked Recessive
пЃєClinical Situation
пЃ№Male is affected with Hemophilia
A
пЃ№Female is normal (non-carrier)
пЃєDraw the Punnett Square
пЃєUse X1 for chomosome with
normal allele and X2 for
chromosome with disease
allele
X-linked Recessive
Punnet Square
X-linked Recessive
пЃєClinical Situation
пЃ№Male is normal
пЃ№Female is a carrier of colorblindness
пЃєDraw the Punnett Square
X-linked Recessive
Punnett Square
X-linked Recessive
пЃєClinical Situation
пЃ№Male is affected with Duschenne
Muscular Dystrophy
пЃ№Female is carrier of Duschenne
Muscular Dystrophy
пЃєDraw the Punnett Square
X-linked Recessive
Punnett Square
пЃєGenotype - The actual gene
constitution of a given person.
пЃєPhenotype - The observable
characteristics of a given
person
пЃєTraits can be environmentally
modified
пЃ№type 2 diabetes
пЃ№PKU
пЃєTraits can be medically modified
пЃ№Sickle cell disease (bone marrow
transplant)
пЃ№Polycysitc kidney disease (kidney
transplant)
пЃєHowever, genotype stays the same
so next generation are not saved
from condition
Group Exercise
Punnet Squares and
Patterns of
Inheritance
пЃєKaryotypes
пЃёThe arranged
representation of the
chromosomal make-up
of a cell nucleus
Chromosomal
Abnormalities
пЃєAbnormalities in number of
chromosomes
пЃ№Caused by nondisjunction:
failure of homologous
chromosomes or sister
chromatids to separate
properly into different
progeny cells
пЃ№Monosomy - condition in which
one chromosome of a pair is
missing from a somatic cell
Monosomy X Turners Syndrome
Monosomy--Turner’s Syndrome
Chromosomal
Abnormalities
пЃєTrisomy - condition in which
one chromosome in the pair is
pesent in three copies in a
somatic cell
пЃєDown Syndrome (21), Trisomy
13 or 18
Klinefelter’s Syndrome - XXY
Abnormalities of Chromosome Number
Trisomy
Chromosomal
Structural
Abnormalities
пЃєDeletions - absence of normal
chromosomal material; can be
terminal or interstitial
пЃєDuplications - presence of an
extra copy of a chromosomal
segment
пЃєInversions - Intrachromosomal
re-arrangement such that the
rearranged section is inverted
пЃєRing Chromosome - Fusion of
the ends of a chromosome
that forms a circle or ring
Chromosomal
Structural
Abnormalities
пЃєTranslocations Interchromosomal
rearrangement; can be
balanced (all chromosomal
material is present) or
unbalanced (chromosomal
material has been gained or
lost); can be reciprocal or
Robertsonian
Structural
Abnormalities
Group Exercise
Karyotype CD-Rom
Congenital
Anomalies
пЃєStructural abnormalities
present at birth
пЃєAre usually not identified with
a known genetic cause
пЃєCause may be a combination
of genetic and environmental
factors
Children at Risk for
Congenital
Anomalies
пЃєPositive family history of
structual anomalies
пЃєChild with one known
structural anomaly
пЃєThe IUGR infant
пЃєThe mentally retarded child
пЃєThe unusual appearing child
Maternal Risk
Factors
пЃєDiabetes
пЃєPhenylketonuria (PKU)
пЃєSeizure disorder
пЃєAlcohol and substance abuse
пЃєRecurrent pregnancy loss
Teratogens
пЃєEnvironmental substances or
exposures that result in
functional or structural
disability.
пЃєAny agent which when given
to or ingested by a pregnant
woman can produce a
permanent morphologic or
functional abnormality.
Agents Which
Cause
Teratogenesis
пЃєDrugs and Chemicals; Alcohol
пЃєInfections (viruses, TORCH)
пЃєRadiation exposure
пЃєFat-Soluble Vitamins
пЃєNicotine
пЃєHeat
Fetal Susceptibility
to Teratogens
пЃєGestational age at the time of
exposure
пЃєDrug dosage
пЃєRoute of administration of
agent
пЃєGenetic predisposition of fetus
to respond to a particular
agent
Gestational
Susceptibility
Factors
пЃє Days 1-17
пЃ№Little effect
пЃє Days 18-60
пЃ№Period of organogenesis
пЃ№Extreme sensitivity to major structural
abnormalities
пЃє Days 61-270
пЃ№Considerably reduced risks
пЃ№Functional abnormalities can still
occur
Pedigrees
пЃєA pictorial representation or
diagram of the family history.
пЃєAllows visualization of
relationships of affected
individuals to other family
members.
пЃєMay indicate a pattern of
inheritance
пЃєHelps pinpoint persons who
should be examined or tested.
Pedigree Format
пЃє3 generations AT LEAST!!
пЃєNote name of informant
пЃєRoman numerals for
generations
пЃєNumber individuals on
pedigree across families
Pedigree Pointers
пЃє Seek a balance between the need for
asking specific versus general questions.
пЃє Ask specific questions about each
individual as you construct the pedigree
(birth defects, mental retardation,
specific traits relevant to the diagnosis or
concern)
пЃє Ask general questions about the whole
family or section of a family. Can you
think of any family characteristics (traits)
or medical problems in more than one
family member?
Pedigree Reminders
пЃєMultiple reproductive
relationships
“Have you had
children/pregnancies by anyone
else?”
“Did you have any pregnancies
prior to this relationship?”
Don’t forget half-sibs,
abortions, miscarriages,
stillbirths, previous marriages.
Pedigree Pointers
пЃєIndicate possible relationships
“Sometimes when there is one
family member with cleft lip and
palate, there are others in the
family with little indentations in
their lower lip, heart problems at
birth, or poor vision and joint
pain. Can you think of anyone
in your family with anything like
that?”
пЃєUse words the clients will
understand
пЃ№seizures = fits = fainting spells
Group Exercise
Final Group Work
Документ
Категория
Презентации
Просмотров
23
Размер файла
8 446 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа