Related Subjects:
|DNA replication
|DNA structure in Nucleus
|Cell Cycle
|Mitosis and Meiosis
|Ribosomes
|Microtubules
|Mitochondria
|Smooth and Rough Endoplasmic Reticulum
Genetic Definitions
- Gene:A region of DNA that encodes a protein.
- Genome:The complete set of genes of an organism, including intervening DNA sequences.
- Locus:The specific location of a gene on a chromosome.
- Chromosome:Self-replicating genetic structure in cells containing DNA; holds a linear sequence of genes. Typically found in pairs; humans have 23 pairs (22 autosomes + 1 sex chromosome).
- Alleles:Alternative forms of a gene at the same locus on a chromosome; each parent contributes one allele per locus.
- Haploid:A single set of chromosomes (half the full set), present in gametes (egg or sperm), containing 23 chromosomes.
- Codon:A sequence of three nucleotides encoding a specific amino acid.
- Karyotype:The number and appearance of chromosomes in the nucleus; humans have 44 autosomes + 2 sex chromosomes.
- Autosome:Any chromosome other than the sex chromosomes; humans have 22 pairs of autosomes.
Genetic Inheritance Patterns: Autosomal recessive conditions are typically metabolic (exceptions: inherited ataxias). Autosomal dominant conditions are generally structural (exceptions: hyperlipidemia type II, hypokalemic periodic paralysis).
Autosomal Recessive Conditions (Metabolic)
These are usually metabolic disorders, except for inherited ataxias:
- Albinism
- Ataxia telangiectasia
- Charcot-Marie Tooth 4
- Hemochromatosis
- Cystic fibrosis
- Cystinosis
- Fanconi anaemia
- Familial Mediterranean fever
- Homocystinuria
- Sickle cell disease
- Thalassemia
- Phenylketonuria
- Refsum's disease
- Lipid storage diseases (e.g., Tay-Sachs, Gaucher's, Niemann-Pick)
- Mucopolysaccharidoses (e.g., Hurler's syndrome)
- Retinitis pigmentosa (autosomal recessive)
- Wilson's disease
Autosomal Dominant Conditions (Structural)
Typically structural conditions, except for Gilbert's syndrome and familial hypercholesterolemia:
- Achondroplasia
- Aniridia
- Tuberous sclerosis
- Charcot-Marie Tooth 1 & 2
- Myotonic dystrophy
- Gilbert's syndrome
- Hyperlipidemia Type 2
- Ehlers-Danlos syndrome
- Facioscapulohumeral muscular dystrophy
- Familial hypercholesterolemia
- Marfan syndrome
- Multiple Endocrine Neoplasia (MEN) syndromes
- Neurofibromatosis 1 and 2
- Polycystic kidney disease
- Retinitis pigmentosa (autosomal dominant)
- Retinoblastoma
- Von Willebrand's disease
X-Linked Recessive Conditions
These conditions typically affect males due to the single X chromosome; females are affected if they have Turner syndrome (only one X chromosome).
- G6PD deficiency
- Hunter syndrome (a type of mucopolysaccharidosis; primarily affects males)
- Hemophilia A and B
- Fabry disease
- Becker and Duchenne muscular dystrophy
- Androgen insensitivity syndrome
- Color blindness
- Lesch-Nyhan syndrome
- Nephrogenic diabetes insipidus
- Ocular albinism
- Retinitis pigmentosa
- Severe combined immunodeficiency
- Wiskott-Aldrich syndrome
X-Linked Dominant Conditions
- Vitamin D-resistant rickets (affects both genders, more severe in males)
- Alport syndrome (85% X-linked dominant)
- Rett syndrome