Introduction to Medical Genetics Dr.Aida Fadhel Biawi , 2013

Genetics concerns the process of trait inheritance from parents to offspring, including the : 1- molecular structure and function of genes 2-gene behavior in the context of a cell or organism (e.g. dominancy) 3- gene distribution and variation and change in populations .

A brief history: 1-The observation of Arabs , ancient Greeks and Hebrews regard genetic phenomena. 2- The experiments of mendel in 1865 on pea. 3- 35 years later, Darwin formulated his theories of volution.

4- In 1900, the principles of Mendel rediscovered by three scientists in three different countries. 5- Also in 1900, Landsteiner discovered ABO blood groups. 6- In 1902 Garrod described alkaptonuria as a( first error inborn of metabolism )

7- In 1909 Johannsen use the term of gene to denote the basic unit of hereditary. 8- Next decades, Muller demonstrated the genetic consequences of ionizing radiation in the fruit fly. 9- In 1944, Avery showed that genes are composed from deoxyriboneuclic acids DNA.

10- In 1953 Waston and Crick they published their paper about physical structure f the DNA formed the basis of what is now known as molecular genetics . 11- The human genome project provide the complete human DNA sequence from 1990-2003.

The genome refers to all of the DNA or genetic material in an organism . What about gene ? Allele ?

Branches of Genetics Medical genetics Microbial genetics Molecular genetics Population genetics Archaeogenetic Psychiatric genetics Quantitative genetics

Medical genetics is the specialty of medicine that involves the diagnosis and management of hereditary disorders.

Microbial genetics is a subject area within microbiology and genetic engineering.

Molecular genetics is the field of biology and genetics that studies the structure and function of genes at a molecular level.

Population genetics is the study of allele frequency distribution and change under the influence of the four main evolutionary processes: natural selection, genetic drift, mutation and gene flow.

Archaeogenetics, a term refers to the application of the techniques of molecular population genetics to the study of the human past.

Psychiatric genetics, a subfield of behavioral neurogenetics, studies the role of genetics in psychological conditions such as alcoholism, schizophrenia, and autism.

Quantitative genetics is the study of the inheritance of continuously measured traits (such as height or weight) and their mechanisms.

What is Medical Genetics? Medical genetics involves any application of genetics to medical practice . .It thus includes : 1- studies of the inheritance of diseases in families 2- mapping of disease genes to specific locations on chromosomes 3- analyses of the molecular mechanisms through which genes cause diseases 4- diagnosis and treatment of genetic disease.

As a result of rapid progress in molecular genetics , gene therapy ( the insertion of the normal genes into patients in order to correct genetic disease ) is now possible . Medical genetics also includes genetic counseling , which involves the communication of information regarding risks , prognoses , and treatments to patients and their families.

Genetic disease A. What is genetic disorder? A genetic disorder is a disease that is caused by an abnormality in an individual’s DNA. Abnormalities can range from a small mutation in a single gene to the addition or subtraction of an entire chromosome or set of chromosomes.

Genetic disease B. Characteristics of genetic disorders 1. congenital 2. mode of inheritance 3. population distribution 4. familial

Genetic disease B. Characteristics of genetic disorders 1. congenital 2. mode of inheritance 3. population distribution 4. familial

Down syndrome albinism

Genetic disease B. Characteristics of genetic disorders 1. congenital 2. mode of inheritance 3. population distribution 4. familial

3 Pedigree of Genetic Disease

Genetic disease B. Characteristics of genetic disorders 1. congenital 2. mode of inheritance 3. population distribution 4. familial

x hemophilia （Blood clotting，to bleed）

Genetic disease B. Characteristics of genetic disorders 1. congenital 2. mode of inheritance 3. population distribution 4. familial

Family number of genetic disease.

Genetic disease B. Characteristics of genetic disorders 1. congenital 2. mode of inheritance 3. population distribution 4. familial

Genetic disease C. Classification of Genetic Disorders 1. single-gene disorders 2. chromosome disorders 3. multifactorial disorders 4. somatic cell genetic disorders 5. mitochondrial disorders

Genetic disease C. Classification of Genetic Disorders 1. single-gene disorders 2. chromosome disorders 3. multifactorial disorders 4. somatic cell genetic disorders 5. mitochondrial disorders

Genetic disease Single-gene disorders result when a mutation causes the protein product of a single gene to be altered or missing.

1-cystic fibrosis 2- fragile X syndrome 3- Sickle cell disease

In Cystic fibrosis: there is a three nucleotide deletion from the coding sequence. This will causes a deletion of Phenylalanine.

Genetic disease C. Classification of Genetic Disorders 1. single-gene disorders 2. chromosome disorders 3. multifactorial disorders 4. somatic cell genetic disorders 5. mitochondrial disorders

In chromosome disorders, entire chromosomes, or large segments of them, are missing, duplicated, or otherwise altered.

Patau syndrome   Trisomy 13 -- the presence of an extra (third) chromosome 13 in all of the cells.

Diagnosis &Treatment Diagnosis: chromosome analysis NO TREATMENT

Genetic disease C. Classification of Genetic Disorders 1. single-gene disorders 2. chromosome disorders 3. multifactorial disorders 4. somatic cell genetic disorders 5. mitochondrial disorders

Genetic disease Multifactorial disorders result from mutations in multiple genes, often coupled with environmental causes.

Influence of environment on some traits ???

Obesity How these genes interact with environmental factors ??

Fingerprints Fingerprints: a polygenic trait Dermatoglyphics: ridges on fingers, palm, toes, and feet Influenced by prenatal environment Nutrition of the mother Rate of finger formation and growth

Others :diabetes, hypertension (high blood pressure), heart-related problems, arthritis, Alzheimer’s disease or even different cancers (breast cancer).

Genetic disease C. Classification of Genetic Disorders 1. single-gene disorders 2. chromosome disorders 3. multifactorial disorders 4. somatic cell genetic disorders 5. mitochondrial disorders

Genetic disease Somatic cell genetic diseases: result from the altered genetic materials in somatic cells. Like cancer.

Genetic disease C. Classification of Genetic Disorders 1. single-gene disorders 2. chromosome disorders 3. multifactorial disorders 4. somatic cell genetic disorders 5. mitochondrial disorders

Genetic disease Mitochondrial genetic diseases: Due to the mutation of mitochondrial DNA. Like leber hereditary optic neuropathy LHON .(loss of central vision )

leber hereditary optic neuropathy LHON .