Download Free Medical Basic Medical Genetics Concepts PowerPoint Presentation

Basic Medical Genetics Concepts PowerPoint Presentation

DOWNLOAD MEDICAL POWERPOINT PRESENTATION

About This Presentation

Description : Check out this medical titled "BASIC MEDICAL GENETICS CONCEPTS”.

This medical is about the basic concepts in medical genetics.

Medical genetics is the branch of medicine that studies the role of genetics in health and disease. Here are some basic concepts in medical genetics:

DNA: DNA, or deoxyribonucleic acid, is the molecule that carries genetic information in all living organisms. It is composed of four nucleotide bases: adenine (A), thymine (T), guanine (G), and cytosine (C).

Genes: Genes are segments of DNA that encode instructions for making proteins. Proteins are the building blocks of cells and perform a variety of functions in the body.

Chromosomes: Chromosomes are structures in the cell nucleus that carry genes. Humans have 23 pairs of chromosomes, for a total of 46.

Alleles: Alleles are different versions of a gene. For example, there are different alleles for eye color, such as brown, blue, and green.

Genotype: An individuals genotype refers to the specific combination of alleles they have for a given gene.

Phenotype: An individuals phenotype refers to the observable characteristics that result from their genotype and interactions with the environment. For example, eye color is a phenotype that is influenced by genetics and other factors such as light exposure.

Inheritance patterns: Different genetic conditions are inherited in different ways. For example, autosomal dominant conditions are caused by a single copy of a mutated gene, while autosomal recessive conditions require two copies of the mutated gene (one from each parent).

Genetic testing: Genetic testing involves analyzing an individuals DNA to look for specific mutations or variations that may be associated with a particular condition.

Genetic counseling: Genetic counseling involves working with a healthcare professional who specializes in medical genetics to discuss the risks and implications of genetic testing and to help individuals make informed decisions about their healthcare.

Tags : medical genetics, DNA, deoxyribonucleic acid, Genes, Chromosomes, Alleles, Genotype, Phenotype, Inheritance patterns, Genetic testing, Genetic counseling, Medical Genetics, Medical Genetics

Published on : Jun 01, 2023 | Views : 1300 | Downloads : 1

Shareable Url :

Embed Code :

Comment

Transcript

Slide 1-

BASIC MEDICAL GENETICS CONCEPTS
Slide 2-

mutation effect on protein function phenotypic expression classes of genetic disease
Slide 3-

Mutations result in different alleles alleles are classified as “dominant” or “recessive” dominant phenotypes – observable in heterozygotes recessive phenotypes – observable only in homozygotes
Slide 4-

loss-of-function (most common) e.g. Decreased amount normal protein: Inborn errors of metabolism as in Tay-Sachs [recessive] Haploinsufficiency as in FH [dominant] gain-of-function e.g. Gene dosage effects as in trisomy 21 [dominant]; Dominant-negative effect as in OI [dominant] Abnormal protein properties as in HD [dominant] novel property e.g. HbS [recessive] inappropriate expression e.g. Oncogenes in cancer Mutations are classified by effect on protein function
Slide 5-

complementation as in XP, profound hearing loss penetrance (100% - achondroplasia - unusual) variable expression Variations in phenotypic manifestation of mutant alleles are due to:
Slide 6-

allelic heterogeneity: hemophilia variants locus heterogeneity: hyperphenylalanemias modifier loci: Waardenburg syndrome (methylation); Alzheimer’s (multiple genes); SNPs environment (XP, α-1 antitrypsin deficiency) Causes of variable expression:
Slide 7-

Common classes of genetic disease: enzyme defects (PKU; Lesch-Nyhan; Tay-Sachs; I-cell disease; XP) Almost always recessive. Pathophysiology due to substrate accumulation,product deficiency, or both. When substrate is diffusible, the pathophysiology is unpredictable; when substrate can’t diffuse, the cell in which it accumulates is damaged. Several enzyme functions can be affected.
Slide 8-

Defects in receptor proteins (Familial hypercholesterolemia) Transport defects (Cystic fibrosis) Disorders of structural proteins (Duchenne muscular dystrophy; Osteogenesis imperfecta) Neurodegenerative disorders (Alzheimer’s disease; triplet repeat disorders) Mitochondrial diseases (MELAS, MERRF) Pharmacogenetic diseases (malignant hyperthermia; G6DP) Common classes of genetic disease (cont.):
Slide 9-

Triplet Repeat Disorders Dynamic expansion of DNA triplet repeats Normal alleles polymorphic Inheritance dominant or recessive Presymptomatic, symptomatic expansion size varies Base sequence, location of repeat varies Parent-of-origin effects on repeat expansion varies (anticipation) Stability during meiosis and mitosis varies (variable expression)
Slide 10-

Huntington Disease (autosomal dominant) Spinobulbar muscular atrophy (X-linked recessive; androgen receptor) CAG repeat Anticipation: expansion occurs preferentially during male gametogenesis Variable expression: mitotic instability low (limited mosaicism) Protein aggregation, not loss-of-function Polyglutamine disorders
Slide 11-

Fragile X Syndrome X-linked recessive CGG repeat in 5’ untranslated region of FRA gene (posttranscriptional regulator; methylation effects) Most common form of hereditary mental retardation Anticipation: expansion occurs preferentially in female gametogenesis Variable expression: Mitotic instability high Disease caused by loss of function; very large expansions needed
Slide 12-

Myotonic Dystrophy Autosomal dominant CTG repeat in 3’ untranslated region of protein kinase gene; mechanism of pathophysiology unknown. Anticipation: either parent can transmit amplified copy; massive expansion occurs only in maternal gametogenesis Variable expression: mitotic instability high Abnormal transcript processing, not deletions, point mutations, etc.
Slide 13-

Freidreich ataxia Autosomal recessive GAA repeat in intron of mitochondrial gene frataxin (involved in iron metabolism). Anticipation: no parent of origin effects Variable expression: mitotic instability low Loss of function 4% are compound heterozygotes (expansion/point mutation)
Slide 14-

Mitochondrial Disorders 3 types of mutations missense mutations in coding regions of genes that alter activity of OXPHOS proteins (Leigh disease-ATPase) point mutations in tRNA or rRNA genes that impair mitochondrial protein synthesis (MELAS; MERRF) rearrangements that generate deletions/duplications in mtDNA ( not usually transmitted from affected mother to offspring; disorders occur as sporadic new cases-Kearns-Sayre syndrome) Maternal inheritance Usually heteroplasmic (phenotypic expression: reduced penetrance, variable expression, pleiotropy)
Slide 15-

Pharmacogenetic Diseases Unanticipated reactions to medications largely/entirely genetic (6.7% incidence in American hospitals; 0.3% fatal). Single gene defects or multifactorial Examples: Malignant hyperthermia (autosomal dominant-Ca+ release channel; other loci) Acute Intermittent Porphyria (autosomal dominant disease: drug-related alteration in gene expression of heme biosynthetic enzyme) G6PD (X-linked recessive; more than 400 variants; most common disease-producing single gene enzyme defect of humans) Acetylation polymorphism (slow or rapid drug inactivation)
Slide 16-

PRINCIPLES OF CLINICAL CYTOGENETICS
Slide 17-

Common chromosome structural disorders Chromosome banding Aneuploidies: nondisjunction Chromosome breakage syndromes; translocation Faulty DNA metabolism chromosome syndromes Genomic imprinting; UDP Sex reversal
Slide 18-

ppt slide no 18 content not found
Slide 19-

Banding
Slide 20-

Banding
Slide 21-

Sister chromatid exchanges in Bloom syndrome
Slide 22-

Banding (FISH)
Slide 23-

Aneuploidy: Nondisjunction
Slide 24-

The phenotypes associated with sex chromosome trisomies are less severe than those associated with autosomal trisomies.
Slide 25-

Clinical phenotype of Turner syndrome is due to haploinsufficiency.
Slide 26-

Structural chromosome abnormalities arising from chromosome breakage: Deletions Ring chromosomes Isochromosomes Translocation
Slide 27-

Cri du chat, 5p- Deletions
Slide 28-

Ring Chromosomes; Isochromosomes
Slide 29-

Translocation examples and consequences
Slide 30-

Translocation Reciprocal translocation Robertsonian translocation
Slide 31-

ppt slide no 31 content not found
Slide 32-

46,XY,t(11;16)(q24;q23)
Slide 33-

Translocation PAIRING AT MEIOSIS
Slide 34-

ppt slide no 34 content not found
Slide 35-

Translocation: non-random X-inactivation
Slide 36-

Structural chromosomal abnormalities arising from faulty DNA metabolism: Slipped mispairing during DNA replication Nonreciprocal recombination
Slide 37-

Slipped mispairing during DNA replication
Slide 38-

N = normal P = unmethylated premutation MN/P = methylated normal or premutation F = methylated full mutation EclXI: methylation sensitive MN/P
Slide 39-

Non-reciprocal recombination
Slide 40-

Non-reciprocal recombination
Slide 41-

Genomic Imprinting: mechanism distribution consequences
Slide 42-

Map of Imprinted Regions in Human Genome Maternally inherited homolog (left) Paternally inherited homolog (right)
Slide 43-

gene A
Slide 44-

Genomic Imprinting
Slide 45-

ppt slide no 45 content not found
Slide 46-

ppt slide no 46 content not found
Slide 47-

Sex Reversal: Role of the sry gene
Slide 48-

ppt slide no 48 content not found
Slide 49-

ppt slide no 49 content not found
Slide 50-

Sex reversal due to translocation of SRY from Y to X