The transfer of genetic traits from parents to children either through sexual or asexual reproduction is referred to as inheritance. All the genetic material for the offspring comes from the parents. Children inherit genes from their parents (characteristics), which is why they resemble their parents. Typically, parents pass on their blood type, eye color, hair color, facial shape, and eye color to their children. This also includes parents’ diseases being passed on to their children.
Autosomal Dominant Meaning
The human chromosome is basically divided into 2 types i.e., Autosomes and Allosomes. Autosomes are chromosomes, not sex chromosomes. Dominant is that gene trait that masks the recessive trait gene expression.
Autosomal Dominant are those genes that are present on the autosome chromosome and are dominant in nature which masks the gene of a recessive trait. These genes express themself in both the Homozygous and Heterozygous conditions.
In the Autosomal Dominant Inheritance method, a child receives the traits from that his or her parents. Heredity, another name for inheritance, is the link between organisms and evolution. The shared inheritance is usually passed down to the offspring through sexual reproduction. When different organisms of the same species mate, 50% of their genes are transferred to the new person. This leads to genetic mixing and variety in an individual. The accumulation of changes over time and over generations is what causes species’ evolution. Genetic inheritance or epigenetic inheritance are the two main general mechanisms through which inheritance can occur. Epigenetic inheritance refers to the transmission of secondary modifications of the genome or chromatin, such as DNA methylation. Genetic inheritance refers to the transmission of the genomic sequence that serves as the basis for DNA replication.
Types of Inheritance
Autosomal Dominant
The term “autosomal dominant” refers to a condition, where a disorder can be brought on by inheriting just one copy of a certain gene variation. A child in this condition has a 50% chance of acquiring the gene mutation from one parent and developing the disease. In autosomal dominant, Only one parent with the altered gene is sufficient to deliver the disorder to the offspring.
Autosomal Recessive
In autosomal recessive inheritance, in order to acquire a particular health condition, a child needs to inherit two copies of the altered gene one from each parent that causes the disorder. The children have a 25% chance of getting an autosomal recessive gene if both parents have it.
X-linked Dominant
The altered gene variant present on the X chromosome which determines sex is responsible for this condition. Since males only have one X chromosome, the disorder is brought on by inheriting one copy of the mutant gene. The symptoms in females, who have two X chromosomes, could be less severe. X-linked disorders can only be inherited by females.
X-linked Recessive
It is a genetic condition where the mutation of the gene is related to the X chromosome. Here, only one recessive allele of the gene is inherited, yet it is expressed. Carrier females transmit the disorder to their sons. Usually, the male-to-male transmission of the disorder is not possible.
Mitochondrial Inheritance
The mitochondrion is a part of the cell that provides energy, they hold a small amount of DNA. A gene variation from mitochondria can be transmitted by a female parent but not a male parent. If a male has the trait and his spouse doesn’t, their offspring won’t have the trait because the condition is passed down from the mother to her offspring.
Many heritable in humans are monogenic as they can be attributed to the variation of a single gene or locus and they isolate in a mendelian inheritance pattern, i.e. Autosomal dominant, autosomal recessive, and sex-linked. Genotype determines the status of a given pair of alleles of genes in an individual, whether it is normal or a variant. Females have 23 pairs of homologous chromosomes (22 pairs of autosomes and one pair of x chromosomes). On the other hand, males have 22 pairs of autosomes, and only one X and one Y chromosome. In females, the status of all genes is either homozygous normal, homozygous variant, heterozygous, or compound heterozygous. In males, genes on the X chromosome, are either hemizygous normal or hemizygous variant, the fact that they have only one X chromosome. The genes present on the Y chromosome are alleles of genes on the X chromosome, and they are termed pseudo-autosomal genes of X and Y.
Autosomal Dominant Inheritance
Autosomal dominant inheritance is a genetic inheritance, which explains how a gene mutation is carried from parent to offspring. In this case, the related rare disease or genetic condition can be caused by just one copy of the gene mutation. Only one mutated copy of the gene is required for a dominant trait to show in a heterozygote, and this trait is often passed down from one generation to the next. A parent with an autosomal dominant trait has a 50% chance of passing that trait on to each of their children. The human body contains 22 pairs of autosomes (non-sex chromosomes) out of a total of 23 pairs of chromosomes, the autosomes, contain the genes responsible for autosomal inheritance. This indicates that prevalence is the same for both males and females.
Autosomal dominant inheritance is the pattern that results from a disorder where the mutated gene is located on an autosome (i.e. not a sex chromosome). The resulting phenotype of the heterozygote and the homozygous variant of the genotype is abnormal. If a parent is heterozygous, the variant is present in only one of the two alleles, and there is a 50% chance of transmission to each offspring. Autosomal dominant inheritance can be recognized by the vertical transmission of the trait (i.e. from parent to children). Formally a trait is called autosomal dominant only when the phenotype of the heterozygote is the same as the homozygous variant. For other dominant traits, the phenotype of the heterozygote is intermediate in severity between that of the two homozygous states (normal and variant). The formal term for this is semi-dominant (or incompletely dominant). Commonly, all human traits that follow either the “true” autosomal dominant or the semi-dominant patterns are called autosomal dominant.
Autosomal dominant traits can exhibit a variety of expressions, reduced heritability, and sex limitation. Dominant trait expression requires a careful physical examination to detect the minute signs that a parent has the gene. Unfortunately, a parent with minor signs of a dominant trait can have a severely affected child. Under certain circumstances, a person who must carry the gene for an autosomal dominant condition fails to show any signs of the condition, such type of gene is said to be ‘non-penetrant’ in that particular individual.
Autosomal Dominant Inheritance Examples
- Huntington’s Disease – This disease is an example of an autosomal dominant disorder. This genetic condition leads to the degeneration of the body’s brain and nerve cells. The mutant huntingtin proteins in homozygotes have not lost their normal function, allowing normal growth and development until the gain of function causes early neuronal death. It affects mainly older adults and leads to the deterioration of their mental and physical abilities. Early symptoms shown during this genetic disorder include memory lapses, stumbling, depression, and mood swings. A cure for this disorder is currently unavailable, and it is usually fatal within 10-25 years of the first onset of symptoms.
- Marfan syndrome – It is an autosomal dominant disorder. Patients affected by this syndrome exhibit some of the cardiovascular and skeletal manifestations, but lack ocular abnormalities. It affects the body’s connective tissue, and one of its main symptoms is over-flexible joints. The affected individuals usually resemble a tall and thin stature. Marfan syndrome is also not usually diagnosed until later in adulthood. A mutation in the FBN1 gene is the main reason causing the syndrome.
- Autosomal dominant polycystic kidney disease (ADPKD) – It is an inherited disease in which the kidneys are the primary site of clusters of cysts, which over time causes the kidneys to get bigger and lose function. Cysts are fluid-filled, spherical, non-cancerous sacs. The cysts can get very large and come in various sizes. The kidneys can be damaged if they have a lot of cysts or big cysts. The liver and other organs can also develop cysts due to polycystic kidney disease. High blood pressure and kidney failure are significant problems that can result from this disorder. The severity of PKD varies greatly, and some consequences can be avoided. Treatments and a change in lifestyle may be able to reduce complications to the kidneys. Polycystic kidney disease is typically caused by abnormal genes, and it runs in families. In a few cases, a genetic mutation can eventually appear on its own (spontaneously).
- Osteogenesis Imperfecta (OI) – It is a group of genetic disorders that mainly affect the development of the bones. People with this condition have very weak bones that break easily, due to a little trauma. However, the severity differs from person to person. Multiple fractures are common, and in severe cases, can even occur before birth. Milder cases involve only a few fractures over a person’s lifetime. Some people may also have dental disease and hearing loss due to this disease. Other symptoms include muscle weakness, loose joints, and skeletal malformations. On the basis of their features and genetic causes, Osteogenesis imperfecta are distinguished into various recognized forms. Depending on the genetic cause, it can be inherited in an autosomal dominant or autosomal recessive pattern.
Autosomal Dominant Pedigree Pattern
- If one of the parents has the autosomal dominant gene then there is a 50% chance that children are affected by the disease.
- If both the parent are hemizygous for the disease then the child is unaffected (get recessive traits from both the parent)
- Progeny has affected genes then the genes pass on to the next generation.
- In pedigree, if the children are affected then their parents are also affected (at least one parent)
- There is a possibility that only one sibling is affected by the disease and not the other sibling.
FAQs on Autosomal Dominant Inheritance
Question 1: What is Autosomal Dominant Inheritance?
Answer:
“Autosomal” in the context of autosomal dominant inheritance refers to a gene located on an autosome. “Dominant” denotes the ability of a single copy of the gene to develop a specific trait.
Question 2: State some examples of Autosomal Dominant Inheritance Disease.
Answer:
Myotonia congenita (Thomsen disease), Myotonic chondrodystrophy (Schwartz-Jampel disease), Paramyotonia congenita, myotonic dystrophy, and Muscle Hypertrophy are some examples of Autosomal dominant disorders.
Question 3: What is the difference between autosomal recessive inheritance and autosomal dominant inheritance?
Answer:
- In autosomal recessive inheritance, in order to pass the trait on to their children, both parents need to carry the trait. Both parents need to pass an altered gene onto their child for their child to inherit the genetic condition.
- In autosomal dominant inheritance, in order to pass the trait to their children, only one parent needs to have an altered gene to pass it on. Half of the children of a parent with an autosomal dominant trait will get that trait.
Question 4: What does Autosomal mean?
Answer:
When a specific gene is not a sex chromosome and is a numbered chromosome it is termed autosomal. Humans have 46 total chromosomes, i.e. 23 chromosomes from each parent. There are two sex chromosomes and 22 numbered chromosomes. The numbered chromosome uses autosomal inheritance.
Question 5: Explain the inheritance pattern of Autosomal Dominant.
Answer:
The infected parent with an autosomal dominant disease has than the disease transferred to the offspring, and the chance transfer of is 50%. But if they parents are not infected then none of the progeny are infected with the disease.
Question 6: Chances of the Autosomal Dominant Inheritance transferring from parent to offspring?
Answer:
There are 50 % chance that the autosomal dominant gene will transfer to the children during the segregation of the gametes.