Chapter 2 Genes and Genetic Diseases Flashcards
Genetic diseases cause (3)
- Errors in duplication process
- Maternal age
- Environmental
Types of generic diseases (2)
- Numerical abnormalities
- Structural abnormalities
Numerical Abnormalities (3)
- Polyploidy
- Triploidy
- Aneuploidy
Polyploidy
Having three or even four times the number of chromosomes
Triploidy
Account for about 10% of miscarriages
Aneuploidy
Abnormal number of chromosomes, usual 45 chromosomes instead of 46
Structural Abnormalities (5)
- Deletions
- Duplications
- Translocations
- Inversions
- Rings
Deletion
Portion of the chromosome is missing or deleted
Duplication
Portion of the chromosome is duplicated, resulting in extra genetic material
Translocation
Portion of one chromosome is transferred to another chromosome
Inversion
Portion of the chromosome has broken off, turned upside down, and reattached
Rings
A portion of a chromosome has broken off and formed a circle or ring
Autosomal aneuploidy example
Down syndrome
Down syndrome implications (6)
- Intellectual disability
- Low nasal bridge
- Epicentral folds
- Protruding tongue
- Low-set ears
- Poor muscle tone
Diagnosis and management of down syndrome (3)
- Genetic testing
- Treat disorder such a heart abnormalities
- Average lifespan 49 years
Sex Chromosome Aneuploidy examples (2)
- Turner syndrome
- Klinefelter syndrome
Turner syndrome characteristics (6)
- Underdeveloped ovaries (sterile)
- Short stature
- Webbing of the neck
- Edema
- Underdeveloped breasts, wide nipples
- Learning difficulties
Klinefleter Syndrome Characteristics (6)
- 2 X’s and 1 Y chromosome
- Male appearance
- Develop female like breasts
- Small testes
- Sparse body hair
- Long limbs
Chromosome breakage
-Physiologic mechanisms will usually repair the break, but the breaks can heal in a way that alters the structure of the chromosome
Castogens
Agents that increase risk of breakage
Deletion
-Breakage or loss of DNA
Cri du chat syndrome
- Deletion of short arm of chromosome
- Low birth weight, severe intellectual disability, and microephaly
Signs and symptoms of cri du chat (5)
- Feeding problems because of difficulty swallowing and sucking
- Severe cognitive, speech, and motor delays
- Unusual facial features
- Behavioral problems
- Excessive drooling
Modes of inheritance of single-gene diseases (4)
- Autosomal dominant
- Autosomal recessive
- X-linked dominant
- X-linked recessive
Autosomal Dominant Inheritance (2)
- Affect offspring usually produced by union of normal parent with affected heterozygous parent
- Allele may be disease causing or normal
Autosomal Recessive Inheritance (2)
- Trait is expressed only when the individual has both abnormal genes from the parent
- Parents may be unaffected carriers yet transmit the trait of the disease to their offspring
- The likelihood that two carries will mate is increased
X-Linked Inheritance (2)
- Sex-linked: genetic conditions caused by mutations on sex chromosomes
- Usually expressed by males because females have another X chromosome to counteract the abnormal gene
X-linked inheritance characteristics of pedigrees (4)
- Most X-linked disorders are recessive
- Affect males cannot transmit the genes to sons, but they can to all daughters
- Females become carriers for the disease
- Sons of female carriers have a 50% risk of be affected
