Introduction:
The human body is marvelous; if one ponders how each system is maintained and run, one is left dumbfounded. Genetic studies, genes, and heredity explain how a feature is passed on to the next generation from the ancestors. Genes determine skin, functioning, maintenance, disorders, and other physiological and anatomical factors of the body.
What Skin Conditions Are Caused Due to Genetic Mutation?
Certain skin disorders occur due to mutations in specific genes. These mutations can be recessive or dominant.
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Recessive Disorders: These mutations are passed on only if both genes in the chromosome are faulty.
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Dominant Disorders: These mutations are inherited even if one gene is faulty.
Some of the skin conditions that are caused due to genetic mutations are:
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Epidermolysis Hyperkeratosis:
The fragility of keratinocytes (cells in the outer layers of the skin) characterizes epidermolysis hyperkeratosis. This leads to the blistering of the skin. The keratinocyte is the cell responsible for producing keratin. Mutation of the gene KRT14 is responsible for the disorder.
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Junctional Epidermolysis Bullosa:
This condition is characterized by blistering and erosion of the skin and mucous membranes. The mutation of the gene LAMA5 causes this.
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Epidermolysis Palmoplantar Keratoderma (EPPK):
EPPK is a dominant skin disorder that presents as a hyperkeratosis on the palms and soles. It has been recently found that the KKT9 gene is responsible for the expression of this condition.
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Hailey-Hailey Disease:
Hailey-Hailey disease is a skin disorder in which the cellular adhesion between the epidermal cells is lost. The gene ATP2C1 is responsible for encoding the calcium pump, which is required for the integrity of the average calcium gradient in the epidermis. Fault in this gene results in the loss of cellular adhesion, which causes plaques, blistering, and erosions.
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Darier's Disease:
Darier's disease is also an autosomal dominant disorder characterized by acantholysis. Acantholysis is the cell separation of the suprabasal epidermal cells, which results in plaques, nail abnormalities, and warty papules.
The ATP2A2 gene, which encodes for ATP-ase of the endoplasmic reticulum, is responsible for cell-to-cell adhesion and keratinization. If this gene is faulty, it can result in
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Dystrophic Epidermolysis Bullosa:
Caused by defects in the anchoring fibrils beneath the basement membrane in the papillary dermis. There are both dominant and recessive forms of dystrophic epidermolysis bullosa. In the dominant form, the anchoring fibrils are scarce, and in the recessive form, they are absent.
COL7A1 has been identified as the mutated gene responsible for the condition; This is because type VII collagen is the main factor in anchoring fibrils, and any defect in the protein can lead to the dermis separating from the epidermis at the level of anchoring fibrils.
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Localized Autosomal Recessive Hypotrichosis:
A desmoglein of the skin and hair follicle that is controlled by the DSG4 gene. The mutation of this gene is responsible for the disorder localized autosomal recessive hypotrichosis.
Certain skin disorders or syndromes such as Werner's syndrome, Cockayne syndrome, Hutchinson-Gilford syndrome, and Rothmund-Thomson syndrome have been found to have associated gene mutations and autosomal recessive inheritance patterns. The defect is mainly found in DNA recombination, replication, repair, and transcription.
How Is Skin Aging Related to Genetics?
The desire to stay young is not a novel concept; from prehistoric times and in ancient civilizations such as Egyptian civilization and in Indian literature dating centuries back, there have been attempts to reverse or stop aging. Skin is the largest organ of the body, the one exposed to rough terrains and harsh environments, and the one that is the first to show signs of aging. Modern medicine, too, has attempted to fight age and, in the process, has found the importance of genetics in skin aging.
Several studies have been conducted to identify the mechanism of aging, improve skin repair, and find anti-aging benefits. Some of these have shown genes are responsible for the following:
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Epidermal differentiation.
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Lipid synthesis.
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Inflammatory response.
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Wound healing; in the molecular function of protease activity, cytokine activity
Hormones are also important in aging, and current practices have found a correlation between genes and hormonal expression. It has been found that specific genes are less expressed in hormone levels found in older populations than in younger ones. Some hormonal irregularities, such as that of growth hormone and pituitary hormone, can present early signs of skin aging, such as wrinkled and dry, thin skin. Obesity, reduced body lean mass, osteopenia (reduction in bone mineral density), rise in cholesterol levels, and premature mortality have also been linked to irregularity between hormones and genes.
Studies in fibroblasts have found that genetic defects can lead to the misregulation of metabolic genes associated with aging. Gender, too, can play a role in skin aging. Males have thicker epidermis, which means a higher number of sebaceous glands. Further, gonadectomy (removal of primary reproductive organs) too can result in the reduction of the thickness of the epidermis.
Studies have found that more and more individuals are spending money on products to reduce skin aging. But skin aging is determined by several factors such as genes, environmental factors, and exposure to the sun, among others. It has been found that 60 % of skin aging variation can be attributed to genetic factors and the remaining 40 % to non-genetic factors.
How Is Skin Cancer Related to Genetics?
About 100 types of tumors have been found associated with the skin; many have been associated with inherited or familial risk factors such as basal cell carcinoma and squamous cell carcinoma, the two most common skin cancers linked to hereditary factors. About 5 to 10% of melanomas (skin cancer) have an autosomal dominant inheritance pattern.
Conclusion:
Skin, the largest organ constantly exposed to varying environmental factors, is mainly affected by genetic factors. Familial tendencies can affect aging, metabolism, certain skin conditions, and even cancers. Gene mapping and genetic studies have helped find the location of gene mutations. This can be revolutionary in genetic counseling for families with a history of certain genetic disorders.
