Ch 3Hereditary Influences on Health Promotion of the Child and Family Flashcards
Genetic Influences on Health
> Human Genome Project
> Pharmacogenetics/Pharmacogenomics
- Allows individualized medication selection and dosing to improve efficacy and safety
> Heredity-environmental interplay in diseases
- Genetic predisposition activated by an environmental trigger
–Multifactorial diseases
Examples of Heredity and Environment Interplay in Human Diseases
> Single-gene disorders
-PKU
> Cancer
> Anomalies from prenatal environmental causes
- Congenital amputation caused by amniotic bands
- Cleft lip and palate
Congenital Anomalies
Deformations
Disruptions
Dysplasias
Malformations
Syndrome
Association
Sequence
Chromosomes
A normal somatic cell has 23 pairs of chromosomes (46 total)
*Suffix “Somy”
Gain or loss of a chromosome
One missing = Monosomy—often result in spontaneous AB—incompatible w/ life
Extra one = Trisomy
Chromosome Disorders
> Definition
- Deviation in structure or number of a chromosome
> Result from
- Duplication of genetic material or
- Loss of genetic material
–“Monogenetic” or “polygenetic” disorders
Chromosome Disorders—Types
Structural abnormality:
> Loss, addition, rearrangement, or exchange of genes of a chromosome
> Usually results from an error in cell division in sperm or ovum (parents are normal
Numeric Chromosome Abnormalities
> Occur whenever entire chromosomes are added or deleted
> Euploidy: Uniform addition of chromosomes to all the original pairs
> Trisomy: Additional chromosome
> Monosomy: Deletion of one chromosome
- Most types are incompatible with life
Autosomal Inheritance Patterns
> Numeric alterations affecting the autosomes
> Examples include some of the most common trisomies:
Trisomy 21 (Down syndrome)
Trisomy 18 (Edwards syndrome)
Trisomy 13 (Patau syndrome)
Syndrome
A recognized pattern of malformations with a single, specific anatomic, physiologic, or biochemical cause
Trisomy 21 = Down Syndrome
> Trisomy—92% of all cases
- Female with a trisomy is 47, XX,+21
- Male with trisomy is 47, XY,+21
- The extra chromosome 21 is unattached and segregates freely during meiosis
- The risk for this type increases with maternal age
> Translocation Down syndrome—4% of all cases
- Male Robertsonian translocation between acrocentric chromosomes 14 and 21 is 46, XY,t(14;21).
- The majority of cases are without family history
- Approximately 25% have one balanced translocation carrier parent
> Mosaic Down syndrome—Rare cases
- The female with mosaic Down syndrome is 46, XX/47, XX,+21.
- Results from mitotic nondisjunction during early embryonic development of a normal zygote. Affected children have mixed cell populations, some with the normal karyotype, others with the extra chromosome.
-The proportion of trisomic cells affects the child’s developmental potential and syndrome-associated potential health problems.
Trisomy 18
AKA. Edwards syndrome
-Severe cognitive impairment and physical abnormalities
-Short life span
Trisomy 13
AKA Patau syndrome
-Severe malformations = greater gene imbalance
-Short life span
Mosaicism
> The presence of two or more chromosomally distinct cell lines in the same individual
> Extent (expressed as a percentage) depends on the stage of embryonic development during which the cell division error occurs
Aneuploidy
An abnormal chromosome pattern in which the total number of chromosomes is not a multiple of the haploid number (23)
The most common aneuploidies in humans are trisomies
Sex Chromosome Aneuploidies
> Alteration in the number of sex chromosomes
> Profound effects are rare
> May have decreased intelligence or learning disabilities
Examples:
Klinefelter syndrome
Turner syndrome
*Klinefelter syndrome occurs when a male has an extra X chromosome.
*Turner syndrome is a genetic disorder in which a female has a single X chromosome compared to the two sex chromosomes in most people.
Autosomal Dominant Inheritance
There is a 50/50 chance of inheritance.
*50% chance of inheriting if parent affected.
Autosomal Recessive Inheritance
There is a 25% inheritance
and 50% chance as carriers
> Offspring of mating between two parents with a recessive gene on an autosome.
> An autosome is any chromosome other than the gamete (sex chromosome). 1 in 4 chance of any offspring having the disease
Both parents are unaffected if the affected individual mates to the normal individual—normal children—all carriers.
X-Linked Recessive Inheritance
> Affected individuals are principally males.
All carrier females are normal.
All affected males have symptoms of the disorder.
Males are not carriers.
IMPACT OF HEREDITARY DISORDERS ON THE FAMILY
Genetic Testing:
> Broadly divided into two categories:
Diagnostic testing
Screening (Prenatal and newborn)
Provides early recognition
Identify carriers
Obtain population data and natural history or genetic variations.
Genetic Evaluation and Counseling
Genetic services
Estimation of risks
Communicating risks
Family History
Family history constructed by the nurse
Pedigree chart
Family tree
Genogram
Role of Nurses in Genetics
> AACN published the revised The Essentials of Baccalaureate Education for Professional Nursing Practice, which establishes essential minimal competencies necessary for nurses to deliver competent genetic- and genomic-focused nursing care
> Nursing Assessment: Applying and Integrating Genetic and Genomic Knowledge
Identification and Referral
