Podcast
Questions and Answers
What is referred to as the study of all genes in the human genome and their interactions with the environment?
What is referred to as the study of all genes in the human genome and their interactions with the environment?
Which molecule is responsible for carrying out the instructions encoded in DNA to synthesize proteins?
Which molecule is responsible for carrying out the instructions encoded in DNA to synthesize proteins?
What does pharmacogenomics specifically study?
What does pharmacogenomics specifically study?
Which term describes the observable characteristics and behaviors resulting from the interaction of genetics and environment?
Which term describes the observable characteristics and behaviors resulting from the interaction of genetics and environment?
Signup and view all the answers
What is epigenetics focused on studying?
What is epigenetics focused on studying?
Signup and view all the answers
What kind of genetic abnormalities can lead to genetic diseases?
What kind of genetic abnormalities can lead to genetic diseases?
Signup and view all the answers
What is the purpose of genotyping single-nucleotide polymorphisms (SNPs)?
What is the purpose of genotyping single-nucleotide polymorphisms (SNPs)?
Signup and view all the answers
What is the main goal of gene therapy?
What is the main goal of gene therapy?
Signup and view all the answers
Which situation exemplifies the impact of environmental factors on genetic expression?
Which situation exemplifies the impact of environmental factors on genetic expression?
Signup and view all the answers
Which of the following genetic disorders is associated with chromosomal aberrations?
Which of the following genetic disorders is associated with chromosomal aberrations?
Signup and view all the answers
What percentage of people can have a life-threatening reaction to a normal dose of codeine?
What percentage of people can have a life-threatening reaction to a normal dose of codeine?
Signup and view all the answers
Which factor is NOT mentioned as influencing child development?
Which factor is NOT mentioned as influencing child development?
Signup and view all the answers
What is the classification of genetic diseases resulting from the interaction of genetic and environmental factors?
What is the classification of genetic diseases resulting from the interaction of genetic and environmental factors?
Signup and view all the answers
According to background statistics, what percentage of all babies born have a birth defect?
According to background statistics, what percentage of all babies born have a birth defect?
Signup and view all the answers
Which genetic disorder is specifically mentioned as a focus of recent gene therapy research?
Which genetic disorder is specifically mentioned as a focus of recent gene therapy research?
Signup and view all the answers
What is the approximate percentage of pediatric hospital admissions that are attributed to children with genetic disorders?
What is the approximate percentage of pediatric hospital admissions that are attributed to children with genetic disorders?
Signup and view all the answers
What was the primary concern in the past regarding genetics?
What was the primary concern in the past regarding genetics?
Signup and view all the answers
Which discovery confirmed that DNA carries genetic information?
Which discovery confirmed that DNA carries genetic information?
Signup and view all the answers
What was significant about the Human Genome Project completed in 2003?
What was significant about the Human Genome Project completed in 2003?
Signup and view all the answers
In what year was the first cloned animal, Dolly the Sheep, created?
In what year was the first cloned animal, Dolly the Sheep, created?
Signup and view all the answers
What percentage smaller is the mouse genome compared to the human genome?
What percentage smaller is the mouse genome compared to the human genome?
Signup and view all the answers
Which year marked the completion of the first comprehensive analysis of cancer genomes?
Which year marked the completion of the first comprehensive analysis of cancer genomes?
Signup and view all the answers
What does the term 'genetics' specifically refer to?
What does the term 'genetics' specifically refer to?
Signup and view all the answers
Which of these discoveries was made in 1968?
Which of these discoveries was made in 1968?
Signup and view all the answers
Study Notes
Introduction to Clinical Human Genetics
- This introduction covers clinical human genetics, including background information on genetics and genomics, historical discoveries, definitions, common syndromes, related practice considerations, recent research approaches and future implications.
Objectives for Today
- Learners will understand genetics/genomics background and history.
- A review of common syndromes, confidentiality issues and knowledge needed in practice.
- An overview of past and present genetic/genomic research approaches and their implications.
- Predictions for the future of genetics and genomics.
The Field of Genetics Has Changed
- In the past, the primary concern was identifying the gene and mutations causing birth defects and illnesses (e.g., Down syndrome, cystic fibrosis, sickle cell anemia, Phenylketonuria.).
- Now, the focus is on more common, complex conditions, patient outcomes, and complex interactions between genes, gene interactions, and environment.
Discoveries Past 100 Years
- 1866: Mendel's research on plants was the first discovery of heredity patterns.
- 1900: The ABO blood group system was the first example of a variable human characteristic inherited according to Mendel's simple rules.
- 1904: Chromosomes are matched pairs, one from each parent.
- 1952: DNA, not protein, carries genetic information.
- 1953: The double helix structure of DNA was discovered.
- 1968: The genetic code was cracked, and the first tRNA molecule was sequenced.
- 1992: Embryo testing for genetic diseases like cystic fibrosis and hemophilia began.
- 1996: Dolly the sheep, first cloned animal.
- 2000: The full genome sequence of the model organism Drosophila melanogaster was completed.
- 2002: The mouse genome sequence was completed.
- 2003: The Human Genome Project was finalized, confirming approximately 20,000-25,000 human genes.
- 2009: The first comprehensive analysis of cancer genomes.
- 2016: Higher copies of gene C4 linked to schizophrenia.
Definitions
- Genetics: Examines DNA sequence on a single chromosome.
- Genomics: Studies all genes in the human genome, including their interactions with each other and the environment. The human genome contains approximately 3 billion DNA base pairs.
- DNA: The molecule carrying the genetic code in most life forms, except for a few viruses.
- RNA: Carries out DNA's instructions to make proteins.
- Pharmacogenomics: How genetic makeup affects a person's response to medications.
- Phenotype: The outcome of genetic and environmental influences, visible characteristics, and behavior.
- Epigenetics: Studies heritable changes in gene function without changing the DNA sequence; these affect how DNA is expressed.
- Genome sequencing & genome-wide association studies (GWAS): Determining genetic markers linked to diseases.
- Gene therapy: Replacing faulty genes with normal copies to treat diseases.
- Chromosomes: 23 pairs, complete copies of ~3 billion DNA base pairs in every cell.
Normal Chromosomes
- Human cells contain 23 pairs of chromosomes.
- A standard karyotype for a standard male.
- A standard karyotype for a standard male; a karyotype for a standard female would only have two X's instead of an X and Y chromosome.
Genetic Diseases
- The etiology of genetic diseases involves changes in DNA structure that impact gene expression.
- Diseases can result from single-gene changes, chromosomal abnormalities, or changes during cellular division.
- Genotyping single-nucleotide polymorphisms (SNPs) reveals how diseases might be associated with specific chromosomes (e.g., 9p21.3, 4q25, and 16q22 are associated with stroke risk).
Epigenetics Example: The Dutch Hunger Winter
- The 1944 Dutch Hunger Winter famine revealed that adults exposed to it during pregnancy carried lasting epigenetic marks.
- These marks increased their children's risk of diabetes, obesity, and schizophrenia later in life.
Gene Therapy
- Gene therapy aims to transfer normal genetic material to faulty genetic material.
- Recent progress includes therapies for cystic fibrosis, primary immunodeficiencies, hemophilia, blindness, and Parkinson's disease.
The Bubble Boy (SCID)
Historical information on the SCID case and gene therapy.
Pharmacogenomics
- Pharmacogenomics promises to personalize treatments based on individual drug response.
- Genetic variation impacts drug responses; certain individuals have significantly different reactions to medications like codeine. (e.g. 20% of Codeine users have little effect, whereas 2% may experience severe reactions).
- 25% of people cannot effectively absorb Plavix, increasing their heart attack/stroke risk.
Background Statistics
- Birth defects affect 3% of newborns.
- 20-30% of infant deaths are due to genetic disorders.
- 11% of pediatric hospital admissions involve genetic disorders.
- 12% of adult hospital admissions relate to genetic causes.
- 50% of mental retardation has a genetic component.
- Child development depends on interacting genetic and environmental factors influencing physical and mental characteristics.
Classification of Genetic Diseases
- Chromosomal aberrations: Loss, addition or structural alterations of chromosomes (e.g., Down syndrome).
- Gene mutations: Mutations in genes or groups of genes (e.g., cystic fibrosis).
- Multifactorial disorders: Complex interactions of multiple genes and environmental factors (e.g., diabetes).
Down's Syndrome (Trisomy 21)
- Results from an extra chromosome 21.
- Associated risk factors include maternal age.
- Individuals with Down syndrome typically exhibit a range of mental and physical characteristics, depending on the severity of the diagnosis.
- Severity based on IQ:
- Mild (80%): 50-70
- Moderate (10%): 35-50
- Severe (10%): 20-40
- Profound (<20)
Trisomy 13
- Incidence of 1 in 25,000.
- Characterized by growth retardation, abnormal eye development, malformed ears, cleft lip/palate, and various other physical abnormalities.
- Severe mental retardation common.
Sex Chromosome Disorders
-
Turner Syndrome (XO): Incidence 1 in 9600
- Characteristics: Short stature, ovarian dysfunction, neck webbing, broad chest, widely spaced nipples, higher risk of renal and cardiovascular abnormalities.
-
Klinefelter Syndrome (XXY): Incidence 1/4000
- Characteristics: Tall stature, narrow shoulders, learning disabilities, often not recognized until puberty, smaller testes and penis.
-
XYY Syndrome: Incidence 1/1000
- Characteristics: Tall stature, normal sexual development, frequently associated with behavioral problems and potential increased aggression, but often intelligence is normal.
Inheritance Patterns
- Autosomal dominant
- Autosomal recessive
- X-linked inheritance
- Multifactorial inheritance
Autosomal Dominant Inheritance
- Males and females are affected equally.
- No skipping of generations.
- Father-to-son transmission can happen.
- Affected individuals often pass the trait to half their children.
Marfan Syndrome
- A tall stature, disproportionately long arms/legs.
- Associated risks include decreased arm span to height, arachnodactyly, dolichocephaly, pectus deformities, and hyperflexible joints.
- Possible complications: mitral/aortic regurgitation, aortic aneurysm, lens dislocation
Neurofibromatosis
- One of the most common inherited disorders (1 in 4000).
- The typical characteristics include café-au-lait spots, neurofibromas, and Lisch nodules.
Achondroplasia
- Autosomal dominant trait (1 in 20,000 births).
- Short stature, short limbs, and lordosis (abnormal spinal curve) are common.
- Regular monitoring of head circumference, muscle tone, hearing, and weight control is essential.
Autosomal Recessive Inheritance
- Affected children inherit the trait from normal parents who are often both carriers.
- The chances of an affected child are increased when there is consanguinity.
- Males and females are affected equally.
Examples of Autosomal Recessive Disorders
- Albinism: Lack of pigment in skin, hair, and eyes.
- Thalassemia: Malformed red blood cells causing anemia.
X-linked Recessive Inheritance
- Affected males inherit the trait from their carrier mothers.
- Affected males transmit the trait to all their daughters, who are usually carriers.
- No father-to-son transmission.
Examples of X-linked Recessive Disorders
- Fragile X Syndrome: The most common form of inherited intellectual disability. Elongated parts of the body, prominent jaw, significant cognitive impairments, and possible behavioral problems.
- Hemophilia: Plasma coagulation factor deficiency. Spontaneous bleeding in joints/muscles/CNS is typical.
Multifactorial Inheritance
- Traits are influenced by multiple genes and also influenced by the environment.
- Is different from mutations at varying loci.
Teratogens
- External agents causing congenital malformations, though the proof that specific substances are teratogenic can be difficult.
Fetal Alcohol Syndrome
- Characterized by small size at birth and throughout childhood
- Often microcephaly, facial features with hypertelorism (wide-set eyes) and a flattened philtrum;
- Associated problems include heart problems and cognitive disabilities.
- Early intervention and monitoring for orthopedic issues are needed.
Prenatal Referrals
- Important for recurrent miscarriages risk.
- Crucial considerations for couples with consanguinity or known teratogenic exposure and risk factors.
- Important screening for reproductive conditions (e.g., sickle cell anemia) for individuals at risk.
The Genetic Revolution
- Discusses advantages and drawbacks of genetic testing.
- Consequences of negative and positive genetic test results.
- Ethical implications of genetic testing.
Future Considerations
- Continuing costs reduction for genome sequencing.
- Potential for genome sequencing to have a wider impact globally.
- The use of larger samples in research to better understand the impact of genetics and environment interactions.
- Impact of environmental factors.
Twin Studies
- Similar genes in identical twins can still vary due to different environments.
- Twin studies showcase how genes often interact with environmental factors to influence traits.
Genome-Wide Association Studies
- GWAS compares the DNA of individuals with different traits or illnesses.
- Data from GWAS helps researchers find correlations between genetic variations and certain traits/diseases, which is placed in large databanks for future research.
Questions
- Question #1: Assessing inheritance patterns from diagrams.
- Question #2: Determining if a child with developmental delays needs further genetic evaluation.
- Question #5: Addressing percentile and genetic concerns in pediatric evaluation.
- Question #4: Providing prenatal recommendations to a mother of a child with a cleft repair.
Conclusion
- Precision medicine, which involves treatment tailored to individual needs, has immense potential to improve healthcare.
- These advancements will transform how healthcare, research, education, and other related systems are conducted, funded, and perceived.
- Collaboration among health professionals is important to handle evolving patient-clinician relationships.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz provides an overview of clinical human genetics, touching on the history, definitions, and common syndromes associated with genetic disorders. It explores recent research in genetics and genomics while considering ethical issues, future implications, and the evolving focus in the field. Perfect for learners looking to grasp the essentials of human genetics.
