NCM 109 (Unit 7): Intro to Genetics and Nursing Clients with Genetic Disorders

Genetics

The study of heredity or how such disorders occur

Heredity

Biological process where a parent passes certain genes onto their children or offspring

DNA

A molecule that encodes an organism's genetic footprint

Chromosomes

Location of DNA

Chromosomes

Are thread-like structures of nucleic acids and proteins

Chromosomes

Carry genetic information

Gene

• Basic unit of heredity

• Determined both the physical and cognitive characteristics of people

• A set of DNA

Nucleus

Center portion of the cell

46 chromosomes

Number of chromosomes in DNA

Gene 23

The sex chromosome

Gametes

• Haploid cells

• Each cell carries only one copy of each chromosome

Zygote

Formed when haploid cells unite and fertilize together = 23 pairs of chromosomes

Diploid cells

Has 2 complete sets of genes

Haploid cell

• Only has a single set of chromosomes which are only the sex cells

Gene locus

Certain areas in a chromosome where specific genes are located for a specific character or trait

Locus

The specific physical location of a gene or other DNA sequence

Allele

Alternative variations or versions of a specific gene

Genotype

• Refers to the genetic code of an individual

• All the info that is found inside the individual’s cells

• Everything that someone inherited from their parents

• Depends on hereditary information

Phenotype

• The expression of the genotype that is visible to other people and can be observed

• Can be influenced by the environment

Genotype

• The particular combination of alleles for a particular gene or locus

Homozygous dominant

2 capital letters e.g. HH

Heterozygous

1 capital letter + 1 small letter e.g. Hh

Homozygous recessive

2 lowercase letters e.g. hh

Examples of observable characteristics (phenotype)

• Behaviour

• Biochemical properties

• Color

• Shape

• Size

Alleles

Are the codes of the specific variation written in DNA

Phenotype

The expressed trait as a result according to the alleles

Punnett squares

• Graphical representation of the possible genotypes of offspring arising from a particular cross breeding event

Genogram

Helps identifying the possibility of a chromosomal disorder occuring in a particular couple's children

Certain body areas where particular attention is needed during physical assessment

• Space between eyes

• Height

• Contour and shape of ears

• Number of fingers and toes

• Presence of webbing (syndactyly)

• Note abnormal fingerprints or palmar creases

• Abnormal hair whorls or hair color

Diagnostic tests

• Maternal serum alpha-fetoprotein

• Chorionic villi sampling

• Amniocentesis

• Percutaneous umbilical blood sampling

• Ultrasound

• Fetoscopy

• Preimplantation diagnosis

• Newborn screening test

Karyotyping

Process of pairing and ordering all the chromosome of an organism

Artificial Insemination by Donor

Use of a surrogate mother

Surrogate embryo transfer

Nondisjunction abnormalities

Deletion abnormalities

Translocation abnormalities

Mosaicism

Isochromosomes

Down syndrome or Trisomy 21

Clinical features of down syndrome

Mgmt of down syndrome

Edward's syndrome

Clinical features of Edward's syndrome

Mgmt of Edward's syndrome

Patau Syndrome

Clinical features of Patau syndrome

Defects of Patau syndrome

Mgmt of Patau syndrome

Cri-du-chat or Cat-cry syndrome

Clinical features of cri du chat syndrome

Turner's syndrome

Clinical feature of Turner's syndrome

Clinical features of Turner's syndrome

S/sx of Turner's syndrome

Mgmt of Turner's syndrome

Klinefelter syndrome

administration of estrogen

• given to pxs with Turner’s syndrome to promote normal sexual development

• if begun at approximately 13 yrs old, secondary sex characteristics appear

osteoporosis

• bone disease prevented during growing years when px with Turner’s syndrome takes estrogen

menstrual flow/ withdrawal bleeding

• effect of taking estrogen 3 out of every 4 weeks in Turner’s syndrome

  • does not correct problem of sterility

testosterone therapy

• treatment given to pxs with Klinefelter syndrome as they enter puberty

• increases strength and muscle size

• increases growth of facial and body hair

inadequate protein synaptic response

• effect of fragile x syndrome in which one long arm of an x chromosome is defective

serotonin agents

• given to pxs with Fragile X syndrome to control behavior

Behavioral features of Fragile X syndrome

Mgmt of Fragile X syndrome

Pompe disease

Pompe disease

• Insufficient functioning of lysosomal acid alpha 1 or acid-alpah glucosidase due to mutation of GAA gene

• causes glycogen build-up; cellular damage in muscles

Mgmt of Pompe disease

Algucosidase alfa

Enzyme med given to px with Pompe disease to remove glycogen in lysosomes

Supportive therapies of Pompe disease

• Mechanical ventilation

• Physical and occupational therapy

• Feeding tube

Tay-Sachs Disease

Tay-Sachs Disease

TSD symptoms (infantile, juvenile, chronic)

TSD (late onset)

Infantile TSD

Onset is 3-6 months TSD

Juvenile TSD

Onset is 2-5 yrs

Chronic TSD

Onset is 10-20 yrs old

Late Onset TSD

20-30 yrs old

S/sx of TSD

Mgmt of Tay-Sachs disease

Mgmt of Tay-Sachs disease (late onset)

Wilson's disease

ATP7B gene

• Cause of mutation leading to copper accumulation in liver and brain in Wilson's disease

S/sx of Wilson's disease

Kyser-Fleischer rings

• Brownish rings from copper deposits in the cornea

• Wilson's disease clinical feature

Clinical features of Wilson's disease

Copper chelation

• involves using medications, like trientine or penicillamine, to bind to and remove excess copper from the body, primarily used to treat Wilson's disease, a genetic disorder causing copper buildup

Mgmt of Wilson's disease

Penicillamine

• Copper chelating agent

• Binds free copper in body making it easier to excrete

Trientine

• Reduces copper reabsorption in urine, therefore increasing the amount of Cu that is excreted in urine

Hereditary hemochromatosis

Clinical features of Hereditary Hemochromatosis

Clinical features of hereditary hemochromatosis

Chondrocalcinosis

Sx of hereditary hemochromatosis causing arthritis

Mgmt of Hereditary hemochromatosis

Venesection

Weekly removal of blood thus removing excess Fe in the bloodstream

Alkaptonuria

Clinical features of Alkaptonuria

Mgmt of Alkaptonuria

Maple Syrup Urine Disease