Genetic diseases are passed down through various inheritance patterns, primarily involving gene mutations transmitted from parents to offspring.
Here's a breakdown of how genetic diseases are passed down:
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Inheritance from Affected Parents: In some cases, a person inherits a genetic disease directly from one or both parents who also have the condition. This occurs when the parent(s) carry a gene mutation that causes the disease.
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New Gene Variants (Mutations): A genetic disease can also arise from a de novo or new mutation in a gene. This means the gene change occurred spontaneously in the egg or sperm or shortly after fertilization. In these instances, there's no family history of the disorder.
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Autosomal Recessive Inheritance: This occurs when both copies of a gene in each cell have a variant (mutation). Individuals with only one copy of the mutated gene are carriers and usually do not exhibit symptoms of the disease. The affected person inherits one mutated copy from each parent.
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Autosomal Dominant Inheritance: This occurs when only one copy of the mutated gene is enough to cause the disorder. If one parent has the disorder, there is a 50% chance that the child will inherit the mutated gene and, therefore, the disorder.
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X-linked Inheritance: These are passed down through the X chromosome. Because males have only one X chromosome, they will express the disease if they inherit one copy of the mutated gene. Females have two X chromosomes, so they are typically carriers if they inherit one copy of the mutated gene, but can express the disease if they inherit two copies.
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Mitochondrial Inheritance: This inheritance pattern involves mutations in mitochondrial DNA. Mitochondria are organelles that generate energy for the cell. Mitochondrial DNA is passed down from the mother to all her children.
| Inheritance Pattern | Description | Example |
|---|---|---|
| Autosomal Dominant | Only one copy of the mutated gene is needed to cause the disorder. | Huntington's Disease |
| Autosomal Recessive | Two copies of the mutated gene are needed to cause the disorder. | Cystic Fibrosis |
| X-linked Dominant | One copy of the mutated gene on the X chromosome is needed to cause the disorder. | Fragile X Syndrome |
| X-linked Recessive | Two copies of the mutated gene on the X chromosome are needed to cause the disorder in females; one in males. | Hemophilia |
| Mitochondrial Inheritance | Passed down from the mother to all her children. | Mitochondrial Myopathy |
Genetic diseases are passed down through specific inheritance patterns determined by the location and nature of the gene mutations involved. Understanding these patterns is crucial for genetic counseling and family planning.
