1. Honors Biology Final Project
Some Common Genetic Disorders That Affect Human Body Systems

2. The Human Genome is made of DNA
The human genome is a book.
This book has 23 chapters, called chromosomes.
Each chapter contains several thousand stories, called genes.
Each paragraph is made up of words, called codons.
Each word is written in letters, called bases.

3. Changes in the Stories are Mutations
We inherit from our parents, a gigantic list of recipes (genes) for making proteins and protein-making machines.
Proteins do almost every chemical, structural and regulatory thing that is done in the body.
Mistakes in writing, copying or reading the recipes lead to abnormal proteins.

4. Types of Mutations in Human Genetic Disease
Substitutions
Frameshifts-deletions, insertions
RNA processing mutations
Regulatory mutations
Expansion of trinucleotide repeat sequences

5. Classification of Genetic Disorders
Single-gene disorders
Chromosome disorders
Multifactorial Disorders

6. Single Gene Disorders: Autosomal Dominant
Marfan Syndrome
Achondroplasia
Huntington Disease
Polycystic Kidney

7. Characteristics of Autosomal Dominant Inheritance
Every affected person in a pedigree has an affected parent, who also has an affected parent, and so on as far back as the disorder can be traced or until the occurrence of the original mutation.

8. Marfan Syndrome
Marfan Syndrome is a connective tissue disorder. One sign is arachnodactyly,long spidery fingers. Premature death is cardiac related.

9. Achondroplasia
Note small stature, short limbs, large head, prominent forehead, low nasal bridge, and lumbar lordosis.

10. Huntington Disease
This is part of a single large Venezuelan pedigree that lead to the discovery of a genetic marker for Huntington Disease.

11. Polycystic Kidney
This photograph shows a cross section of a polycystic kidney. Patients present with multiple symptoms related to their urinary tract.

12. Single Gene Disorders: Autosomal Recessive
Cystic Fibrosis
Phenylketonuria
Sickle Cell Anemia
Tay-Sachs Disease

13. Characteristics of Autosomal Recessive Inheritance
Males and females are equally affected
Disorder seen in other siblings but not in parents or other relatives
Parents are asymptomatic carriers of mutant alleles
Parents may be consanguineous (related to a close common ancestor) especially for rare disorders
Recurrence risk is ¼ siblings

14. Cystic Fibrosis
This cross section of the lung of a cystic fibrosis patient exhibits mucus plugs and purulent secretions within the airways.

15. Phenylketonuria
A classic “inborn error of metabolism” disorder in which the lack of PAH prevents the breakdown of the amino acid, phenylalanine.

16. Sickle Cell Anemia
A scanning electron micrograph of red cells from a patient with sickle cell disease- the classic sickle shape is seen only when cells are in the deoxygenated state.

17. Tay-Sachs Disease
This disorder was named after Warren Tay, a British ophthalmologist who noted the cherry red spot in children suffering from Tay-Sachs. Bernard Sachs was a neurologist also studying this disorder.

18. Single Gene Disorders: X Linked
Duchenne Muscular Dystrophy
Hemophilia

19. Charcteristics of X-Linked Recessive Inheritance
Incidence of trait much higher in males than in females
Heterozygous females are usually unaffected
The responsible gene is transmitted from an affected man through all his daughters
Any of the daughter’s sons has a 50% chance of inheriting the condition
A significant proportion of isolated cases are due to new mutation

20. Duchenne Muscular Dystrophy
This classic
“Gowers maneuver” is used by people with muscular dystrophy to rise from the ground.

21. Hemophilia
Subcutaneous hematoma of the forehead of a young boy with hemophilia.

22. Chromosome Disorders: Aneuploidy
Down Syndrome

23. Chromosome Disorders
These disorders are not due to a single mistake in the genetic blueprint but to an excess or deficiency of the genes contained in whole chromosomes or chromosome segments.
These are quite common, affecting 7/1000 liveborn infants and accounting for about half of all spontaneous first-trimester abortions.

24. Normal Male Karyotype
A normal human genome consists of 23 pairs of chromosomes, one from Mom and one from Dad.
Too many or too few chromosomes is called aneuploidy.

25. Down Syndrome
Note the classic facial features of a young child with Down Syndrome- the epicanthic folds, small jaw, and protruding tongue.

26. Multifactoral Inheritance: Genetic/Environmental
Insulin-Dependent Diabetes Mellitus

27. Multifactorial Inheritance
There appears to be no single error in the genetic information, but rather
a combination of small variations in genes that together can predispose or produce a serious defect, often in concert with environmental factors.
Multifactorial disorders tend to recur in families but do not show the charcteristic pedigree patterns of single-gene traits.

28. Genetic Disorders Affect Human Body Systems
Marfan Syndrome
Achondroplasia
Huntington Disease
Polycystic Kidney
Cystic Fibrosis
Phenylketonuria
Sickle Cell Anemia
Tay-Sachs
Muscular Dystrophy
Hemophilia
Down Syndrome
Diabetes
Cardiovascular/multiple
Skeletal
Nervous
Excretory
Respiratory
Digestive
Hemoglobin Formation
Muscular
Blood Clotting Mechanism
Endocrine