Introduction
Traits caused by a combination of hereditary, environmental, and unpredictable influences are referred to as multifactorial inheritance. These features are different from a polygenic inheritance, which refers to traits that are the consequence of many genes acting together. Within families, multifactorial traits segregate, but there is no uniform or recognised inheritance pattern.
Multiple genes are involved in the expression of several characteristics. Each gene contributes or subtracts from the trait in a way unaffected by other genes. Many characteristics follow a bell-shaped distribution. Because people are unlikely to inherit numerous factors acting in the same direction, fewer people are at the extremes, and many more are in the middle.
Table of Contents
- What is Multifactorial Inheritance?
- Multifactorial Disease Characteristics
- Different Kinds of Multifactorial Traits and Disorders
- Multifactorial versus Polygenic Inheritance
- Frequently Asked Questions (FAQs)
What is Multifactorial Inheritance?
The term “multifactorial inheritance” refers to the notion that a congenital disability is caused by “many factors.” The traits or conditions are frequently caused by a combination of genes from both parents and unknown environmental variables. Environmental factors playing a vital role include the following:
- Alcohol and tobacco
- Nutrition
- An illness
- Lifestyle
- Pollution
- Some medicines
In multifactorial traits, one gender (either male or female) is typically influenced more than the other. There seems to be a different “threshold of expression” for each gender, implying that one gender is more likely than the other to exhibit the condition. Hip dysplasia, for example, is nine times more frequent in women than in men.
The most common type of diabetes, type 2, is multifactorial. It’s caused by the inheritance of susceptibility genes (genes that make you more likely to get diabetes) as well as environmental variables like obesity. Obesity, on the other hand, is certainly multifactorial in nature.
Also read:
What is Polygenic Inheritance?
Multifactorial Disease Characteristics
A multifactorial disease has a number of distinguishing traits that distinguish it from Mendelian or sex-limited diseases. The following are some of these characteristics:
- Affected children born to unaffected parents can develop the condition in isolation. There is no apparent Mendelian pattern of inheritance, despite the fact that familial aggregation is widespread (i.e. numerous cases may exist in the same family).
- Environmental factors might either enhance or decrease the disease’s risk.
- The sickness affects one gender more than the other, although it is not a gender-specific feature. Furthermore, first-degree relatives of persons from the less commonly affected gender are at a higher risk of contracting the condition.
- Mendelian proportions are contradicted by the concordance rates in monozygotic and dizygotic twins. A concordance rate is a measurement of how often both twins have the same condition.
- A particular ethnic group is more susceptible to the disease.
Different Kinds of Multifactorial Traits and Disorders
The following are some of the health issues that are caused by both genes and external factors:
- Diabetes
- Schizophrenia
- Alzheimer disease
- Bipolar disorder
- Arthritis
- Osteoporosis
- Allergies and asthma
- High cholesterol and blood pressure
- Ovarian, breast, bowel, prostate, and skin cancers
- Skin conditions including psoriasis, moles, and eczema
- Other autoimmune disorders, including Multiple sclerosis
- Neural tube abnormalities and cleft palate are examples of congenital disabilities
Multifactorial versus Polygenic Inheritance
The primary difference between multifactorial inheritance and polygenic inheritance is that multifactorial traits are influenced by various genes and environmental factors, whereas several genes influence polygenic traits.
The environment strongly controls multifactorial traits. Whereas, polygenic traits may or may not be influenced by the environment.
Multifactorial traits might be continuous or discontinuous, whereas polygenic traits are always continuous.
Related Links:
- Mendel’s Laws of Inheritance
- Heredity
- How Chromosomes Are Involved in the Process of Inheritance?
- What Is Biological Inheritance?
- How Does Multiple Alleles Affect Inheritance?
Frequently Asked Questions
Define Mendelian Inheritance.
Specific patterns of how traits are passed from parents to offspring are referred to as Mendelian inheritance. Gregor Mendel, an Austrian monk who did thousands of tests with pea plants in the 19th century, developed these general patterns.
Mendel proposed the law of inheritance from the first to the second generation. The three laws that make up the law of inheritance are the law of dominance, the law of segregation, and the law of independent assortment.
Is eye colour multifactorial?
Eye colour was once assumed to be a simple Mendelian feature, meaning that it was determined by a single gene, with brown being dominant and blue being recessive. Eye colour is now known to be a polygenic trait, meaning that it is determined by numerous genes.
What are the risks that run in the family due to Multifactorial Inheritance?
Multifactorial disorders are more likely to run in families. This is due to the fact that genes have a role in their development. Your chance of developing a multifactorial trait or condition is proportional to how closely you are related to someone who has the trait or condition.
If your sibling has a trait or disorder, you’re more prone to acquire it. If a cousin has it, you’re at a reduced risk. Depending on their position in the family tree, family members share a part of their genes. About half of our genes are shared by our parents, siblings, and children. However, since multifactorial disorders are caused by multiple factors, determining a person’s true risk of acquiring a disorder or passing it on can be difficult.
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