Genetics and Genetic Counselling Flashcards
Study of the way such disorder occur
Genetics
Study of chromosomes by light microscopy and the method by which chromosomal aberrations are identified
Cytogenetics
Basic units of heredity that determine both the physical and cognitive characteristics of people
Genes
Composed of segments of DNA (Deoxyribonucleic acid) that are woven into strands in the nucleus of all body cells
Chromosomes
Refers to his or her outward appearance or the expressions of genes
Phenotype
Refers to his or her actual gene composition
Genotype
The complete set of genes
Genome
What is the numerical value of a complete set of genes?
50,000 - 100,000
A person who has two like genes for a trait – two healthy genes, for example (one from the mother and one from the father)
Homozygous
The genes differ (a healthy gene from the mother and an unhealthy gene from the father, and vice versa)
Heterozygous
Either a person has two unhealthy genes (is homozygous dominant) or is heterozygous – with the gene causing the disease stronger than the corresponding healthy recessive gene for the same trait
Autosomal Dominant Disorders
Tend to be biochemical or enzymatic
Autosomal Recessive Inheritance
The disease does not occur unless two genes for the disease are present (homozygous recessive pattern)
Autosomal Recessive Inheritance
Some genes for disorders are located on, and therefore transmitted only by, the female sex chromosome (the X-chromosome)
X-Linked Dominant Inheritance
If the affected gene is dominant, only one X-chromosome with the trait need to be present for symptoms of the disorder to be manifested
X-Linked Dominant Inheritance
The majority of X-linked inherited disorders are not dominant but recessive
X-Linked Recessive Inheritance
When the inheritance of a recessive gene comes from both parents (homozygous recessive), it appears to be incompatible with life
X-Linked Recessive Inheritance
A progressive neurologic disorder, characterized by loss of motor control and intellectual deterioration that is heterozygous inherited autosomal dominant disorder
Huntington disease
Disorder results in muscle weakness
Facioscapulohumeral Muscular Dystrophy
Disorder in which bones are exceedingly brittle
Osteogenesis Imperfecta
Disorder of connective tissue that results in an individual being thinner and taller that usual and perhaps with associated heard disorder
Marfan Syndrome
Accounts for 5% - 10% of breast cancer in women
Breast and Breast/Ovarian Cancer Syndrome
Extra chromosome 13 and is severely cognitively challenged
Trisomy 13 - Patau Syndrome
Has 3 copies of chromosome 18
Trisomy 18 - Edwards Syndrome
The result of a missing portion of chromosome 5
Abnormal cry which sounds like a cat
Cri-Du-Chat Syndrome
Has only one functional X-chromosome
Turner Syndrome
Has two X-chromosomes and a Y-chromosome
Klinefelter Syndrome
The most common cause cause of cognitive challenge in biologic males
Fragile X-Syndrome
