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GeneticsGenetics
By: Mrs. Mahdiah Samaha AlkonyBy: Mrs. Mahdiah Samaha Alkony
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introductionintroduction
There is an ongoing need to identify women with increased risk of having a child with a serious genetic disorder so that they can be offered genetic counseling and appropriate genetic testing.
Nurses are needed to actively identify and refer high-risk patients and their families to appropriate professionals and to meet the special psychosocial needs of those women who must deal with genetic disorders and congenital anomalies.
Nurses, as primary providers of health services, are in a unique position to meet these challenges.
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DefinitionDefinition
Genetics: is the science of heredity Genes: are the coded sequence of information to which
cellular organisms regulating their embryologic development, metabolic functioning, growth, and reproductive.
Approximately 1 in 50 newborns(2%) has a major congenital abnormality
60% of these abnormalities are caused by environmental factors and nutritional deficiencies.
40% are thought to be hereditary 60% of the first trimester spontaneous abortion the
conceptus has chromosomal abnormalities.
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BURDEN OF GENIRITICBURDEN OF GENIRITICDiseases to family of communityDiseases to family of community
Financial cost to family
Decrease in planned family size
Loss of family integrity
Social Isolation
Lifestyle alteration
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BURDEN OF GENIRITICBURDEN OF GENIRITICDiseases to family of Diseases to family of
communitycommunity Disruption of husband-wife relationship
Threatened family self concept
Psychological damage
Physical health problems
Loss of dreams at aspiration
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Etiology of genetic Etiology of genetic disordersdisorders
Chromosome disorders demonstrate change in the number or structure of an individual’s chromosome complement.
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Types of chromosomes
abnormalities
Monosomy: is the absence of a single chromosome and is almost always lethal to the embryo.
Trisomy: is the presence of an extra chromosome and is also usually incompatible with life.
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Causes of chromosomal Causes of chromosomal abnormalitiesabnormalities
Radiation Drugs Viruses Toxins Chemicals Women whose age is 35 years or more are at risk to
get Down syndrome. This group of women must be referred to genetic counseling.
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((22 ) )Single gene inheritanceSingle gene inheritance
Refer to those genetic diseases that are caused by a gene mutation at a single site on a chromosome.
1. Autosomal dominant
2. Autosomal recessive
3. X-linked dominant
4. X-linked recessive
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((33 ) )Multifactorial InheritanceMultifactorial Inheritance
Those traits and disorders that arise as a result of the interaction of genetic and environmental factors.
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Newborn genetic screening
Aim is to:Aim is to:Identify those pre symptomatic newborns affected with a
genetic metabolic disease so that preventive treatment can be initiated before permanent damage is done.
Screening done by obtaining sample from:1. cord blood2. Newborn nursery blood3. Newborn follow-up blood4. Newborn follow-up urine
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Microbiologic assays screen done for:
Phenylketonuria( PKU)Phenylketonuria( PKU) GalactosemiaGalactosemia Screening for congenital hypothyroidismScreening for congenital hypothyroidism screening for hemoglobinopathies screening for hemoglobinopathies screening for cystic fibrosis screening for cystic fibrosis
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Maternal serum Maternal serum screeningscreening Alpha-fetoproteinAlpha-fetoprotein Sickle cell diseaseSickle cell disease Beta thalassemiaBeta thalassemia
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Prenatal diagnosisPrenatal diagnosis
Amniocentesis Fetoscopy Chorionic villi sampling Ultrasonography Chromosome analysis
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Genetic counselingGenetic counseling
Who should be offered prenatal diagnosis?Who should be offered prenatal diagnosis? Maternal age 35years or moreMaternal age 35years or more Previous history of chromosomal abnormalities Previous history of chromosomal abnormalities Family history of metabolic or structural autosomal Family history of metabolic or structural autosomal
recessive or dominant disorder.recessive or dominant disorder. Couples who have a previous personal or family Couples who have a previous personal or family
history of first or second-degree relative of a neural history of first or second-degree relative of a neural tube defect.tube defect.
Clients who exhibit extreme anxiety or concern Clients who exhibit extreme anxiety or concern
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Components of genetic counselingComponents of genetic counseling::
Initial interviewInitial interview Family historyFamily history Assessment of clientAssessment of client Establishment of accurate diagnosisEstablishment of accurate diagnosis Supplementary tests proceduresSupplementary tests procedures Literature search and reviewLiterature search and review Consultation with other expertsConsultation with other experts Determination of recurrence risk Determination of recurrence risk
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Components of genetic counselingComponents of genetic counseling::
Communication of the results and risks to Communication of the results and risks to client and familyclient and family
Discussion of optionDiscussion of option Review of questionsReview of questions Referral, e.g. amniocentesisReferral, e.g. amniocentesis Follow-upFollow-up Evaluation Evaluation