One would be reasonable to think that with so much information stored on the DNA that errors must happen pretty often. However, the DNA is usually very accurate and almost error-free. When errors occur; even small ones, disease may be the result. Here is an outline of what to expect. 

Autosomal Dominant Disorders

Disorders of the autosomal chromosomes caused by a dominant defective trait on a heterozygous allele. Conditions include:

  • Polydactyly: Having extra fingers
  • Achondoplasia: Dwarfism
  • Marfan syndrome: Defective connective tissue affecting eyes, heart, blood vessels and bones. People with this disease are generally tall and thin with long arms, fingers and toes. Scoliosis is also associated with this disease 
  • Familial hypercholesterolemia: Inefficient removal of cholesterol from the blood

Autosomal Recessive Disorders

Disorders of the autosomal chromosomes caused by two recessive defective traits on a homozygous allele. Conditions include:

  • Cystic fibrosis: Overproduction of thick mucous that clogs the lungs
  • Hemochromatosis: Too much iron absorption. This disease is associated with darker skin pigmentation and irregular hear rhythm
  • Phenylketanuria: Inability to metabolize phenylalanine; an essential amino acid
  • Galactosemia: Inability to metabolize galactose. This may lead to impair mental development and liver damage
  • Sickle cell anemia: Production of deformed red blood cells that have the shape of a sickle. Sickled blood cells are not able to properly transport oxygen
  • Tay-Sachs: Disease that destroys nerve cells in the brain and spinal cord 
  • Albinism: Absence of skin pigmentation resulting in colorless white skin

Sex-Linked Inheritance Diseases

Diseases caused by a defective gene on the sex chromosome. Conditions include:

Abnormal Chromosomal Diseases

Diseases caused by defects on the chromosomes; either the number or structure. Conditions include:

  • Down Syndrome: Disorder caused by trisomy on number 21 chromosome. This result in some mental impairment and may also be associated with respiratory problems, heart disease and leukemia

Sex Anomalies

  • Turner’s Syndrome: Disorder caused by females having only one X chromosome. This condition leads to short stature, delayed puberty, infertility, heart defects, and certain learning disabilities.
  • Klinefelter’s Syndrome: Disorder in males caused by having an extra X chromosome. This results in some feminine features including enlarged breast and reduced facial hair. Testes are small and testosterone production is low leading to infertility
  • Hermaphroditism: Chromosomal sex is different from anatomical sex or in very rare causes having both sex organs
Courtney Simons
Courtney Simons is a food science professor. He holds a BS degree in food science and a Ph.D. in cereal science from North Dakota State University.
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