xeroderma pigmentosum group C

Xeroderma pigmentosum group C (XPC) is a DNA damage recognition protein that plays a crucial role in the initiation of global-genomic nucleotide excision repair (NER). This process helps to correct DNA damage caused by ultraviolet (UV) radiation, which can lead to mutations and cancer.

According to research [6], XPC is essential for the early recognition of NER, binding to damaged DNA and recruiting other proteins to facilitate repair. Mutations in the XPC gene have been associated with xeroderma pigmentosum, a rare autosomal recessive disorder characterized by increased sensitivity to sunlight and a predisposition to skin cancers [8].

Studies have shown that XPC is involved in the recognition of UV-induced DNA damage, including cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts (6-4PPs) [9]. The protein's ability to bind to these damaged regions allows for the recruitment of other proteins necessary for NER.

In individuals with xeroderma pigmentosum, mutations in the XPC gene lead to impaired DNA repair mechanisms, resulting in increased sensitivity to UV radiation and a higher risk of skin cancers. This condition is often characterized by severe photosensitivity, skin pigmentary changes, and malignant tumor development [11].

Overall, XPC plays a vital role in maintaining genome stability by facilitating the repair of UV-induced DNA damage. Its dysfunction has significant implications for human health, particularly in the context of xeroderma pigmentosum.

References: [6] NA Nasrallah · 2022 · Cited by 14 — Xeroderma pigmentosum complementation group C (XPC) is a DNA damage recognition protein essential for initiation of global-genomic nucleotide excision repair ( ... [8] Xeroderma pigmentosum (XP) is a rare autosomal recessive disorder of DNA repair primarily characterized by photosensitivity and predisposition to skin cancers. [9] by LC YANG · 2015 · Cited by 5 — Xeroderma pigmentosum group C (XPC) is a DNA damage recognition protein that functions in the early recognition of nucleotide excision repair (NER) and binds to ... [11] Xeroderma pigmentosum is a rare autosomal recessive genodermatosis that results due to mutations in nucleotide excision repair. The condition is characterized by severe photosensitivity, skin pigmentary changes, malignant tumor development, and occasionally progressive neurologic degeneration.

Common Signs and Symptoms of Xeroderma Pigmentosum Group C

Xeroderma pigmentosum (XP) group C is a rare genetic disorder characterized by severe sensitivity to ultraviolet (UV) light. The signs and symptoms of XP group C typically appear in infancy or early childhood and can vary from person to person.

Common Symptoms:

• Severe sunburn: People with XP group C experience severe sunburn after minimal exposure to UV light, often within a few minutes.
• Freckling: Freckles or freckle-like lesions (lentigines) appear in sun-exposed areas, such as the face, hands, and arms.
• Dry skin: Dryness and changes in skin pigmentation are common symptoms of XP group C.
• Eye problems: Eye symptoms, including dry eye, eyelid degeneration (atrophy), and photophobia, can occur.

Other Possible Symptoms:

• Nervous system problems: Some people with XP group C may experience progressive neurological degeneration, which can lead to symptoms such as:
  • Hearing loss
  • Muscle tightness
  • Lower tendon reflexes
  • Seizures

Early Warning Signs:

• A tendency to sunburn is often the earliest sign of XP group C.
• Freckling in sun-exposed areas may also be an early warning sign.

It's essential to note that these symptoms can vary in severity and may not appear at all in some cases. If you suspect someone has XP group C, it's crucial to consult a dermatologist or geneticist for proper diagnosis and treatment.

References:

• [1] Xeroderma pigmentosum eye symptoms.
• [2] Xeroderma pigmentosum (XP) is characterized by: Acute sun sensitivity (severe sunburn with blistering, persistent erythema on minimal sun exposure) with marked freckle-like pigmentation of the face before age two years; Sunlight-induced ocular involvement (photophobia, severe keratitis, atrophy of the skin of the lids, ocular surface neoplasms);
• [3] The signs of xeroderma pigmentosum usually appear in infancy or early childhood. About half of affected children develop a severe sunburn after spending just a few minutes in the sun.
• [11] Xeroderma Pigmentosum Symptoms . From a very young age, people with XP experience serious damage from even minor sun exposure. ... About 25% of patients may also develop neurological signs, possibly from a loss of nerve cells in the brain. These symptoms may involve progressive hearing loss, muscle tightness, lower tendon reflexes, seizures

Diagnostic Tests for Xeroderma Pigmentosum Group C (XPC)

Xeroderma pigmentosum group C (XPC) is a rare inherited disorder characterized by extreme sensitivity to ultraviolet radiation exposure. Diagnosing XPC requires a combination of clinical findings, family history, and specialized DNA repair tests.

Specialized DNA Repair Tests

The diagnosis of XPC is established through the following DNA repair tests:

• Unscheduled DNA Synthesis (UDS) test: This test measures the rate of DNA synthesis in cells exposed to UV radiation. A deficiency in UDS indicates a problem with nucleotide excision repair, which is characteristic of XPC.
• UV Survival assay: This test assesses the ability of cells to survive exposure to UV radiation. Cells with impaired nucleotide excision repair are more sensitive to UV radiation and may not survive as well as normal cells.
• Recovery of post-UV DNA/RNA synthesis (RRS, RDS) analysis: This test evaluates the recovery of DNA and RNA synthesis in cells after exposure to UV radiation. A deficiency in this process indicates a problem with nucleotide excision repair.

Other Diagnostic Tests

In addition to these specialized DNA repair tests, other diagnostic tests may be used to confirm the diagnosis of XPC, including:

• Skin biopsy: This involves studying skin cells in the laboratory to look for signs of impaired nucleotide excision repair.
• DNA testing: This can involve sequencing the genes involved in nucleotide excision repair to identify mutations that may contribute to XPC.

References

• [11] Diagnostic Tests. The diagnosis of XP is made by DNA repair tests such as the measurement of UV-induced DNA repair synthesis (unscheduled DNA synthesis, UDS), UV survival and the analysis of the recovery of post-UV DNA/RNA synthesis (RRS, RDS). The DNA repair parameters are listed in Table 1.
• [12] Xeroderma pigmentosum (XP) is a group of rare inherited human neurocutaneous diseases, and the group C (XPC) is the major group of patients with XP in Europe, North America, and South America. Current molecular diagnostic methods for XP require specialized, expensive, and time-consuming UV sensitivity and DNA repair assays followed by gene ...

Treatment Options for Xeroderma Pigmentosum Group C (XPC)

Individuals with xeroderma pigmentosum group C (XPC) have a rare genetic disorder that makes them extremely sensitive to ultraviolet radiation, leading to an increased risk of skin cancer. While there is no cure for this condition, various treatment options are available to manage its symptoms and prevent further complications.

• Antioxidant drugs: These medications can help reduce the damage caused by UV radiation and may be prescribed to individuals with XPC.
• Retinoic acid derivatives: Derivatives of vitamin A, such as isotretinoin, have been used to treat skin growths and prevent additional ones from forming.
• Imiquimod 5% cream: This topical cream has been applied in combination with oral acitretin (20 mg/d) for 4-6 weeks to treat skin lesions.
• Acitretin: A high dose of this special form of vitamin A may be prescribed to prevent additional skin growths from forming.
• 5-fluorouracil: This medication has been used to treat skin tumors in individuals with XPC.

Other Treatment Options

In addition to these medications, other treatment options are available for individuals with XPC. These include:

• Surgical removal of skin growths: Individuals may be regularly seen by dermatologists to remove skin growths.
• Palliative therapeutics: While not a cure, palliative therapeutics can help limit the progression and development of skin cancer.

Important Considerations

It is essential for individuals with XPC to avoid exposure to UV radiation as much as possible. This includes:

• Avoiding direct sunlight: Individuals should take precautions to avoid direct sunlight, especially during peak hours.
• Wearing protective clothing: Wearing protective clothing and applying sunscreen can help reduce the risk of skin damage.

References

[8] Xeroderma pigmentosum, commonly known as XP, is an inherited condition characterized by an extreme sensitivity to ultraviolet radiation (UVR). [9] Numerous studies have demonstrated that the administration of topical 5-FU to XP patients has roles in cancer prevention and progression. [10] Though the therapeutic strategies have roles in cancer prevention and progression, they cannot overcome the incapacity of the nucleotide excision repair system to remove DNA lesions in XP patients.

Note: The references provided are based on the search results within the context.

Based on the provided context, here are some conditions that may be considered in the differential diagnosis for xeroderma pigmentosum group C (XPC):

• Acanthosis Nigricans: This is a skin condition characterized by dark, velvety skin patches, particularly in the folds and creases of the body. While it can appear similar to some symptoms of XPC, such as skin changes, it is not directly related to DNA repair defects.
• Acute Cutaneous Lupus Erythematosus (ACLE): This is a type of lupus that affects the skin, causing inflammation and lesions. Like acanthosis nigricans, it may present with similar symptoms to XPC but is not caused by DNA repair defects.
• Basal cell nevus syndrome: Also known as Gorlin syndrome, this is a rare genetic disorder characterized by multiple basal cell carcinomas, jaw cysts, and other skeletal abnormalities. While it shares some similarities with XPC in terms of skin cancer risk, it is caused by mutations in the PTCH1 gene.
• Bloom Syndrome: This is a rare autosomal recessive disorder characterized by short stature, facial features, and an increased risk of various cancers, including skin cancer. Like XPC, it involves defects in DNA repair mechanisms but is caused by mutations in the BLM gene.

It's essential to note that these conditions may present with overlapping symptoms, making differential diagnosis challenging. A comprehensive evaluation, including genetic testing and clinical assessment, is necessary to accurately diagnose xeroderma pigmentosum group C (XPC).

References:

• [1] Review by Li et al., 1993: This study discusses the genetic heterogeneity of xeroderma pigmentosum and mentions XPC as a common form in the white population.
• [2] Dec 15, 2019 - Differential Diagnoses: This search result provides a list of conditions that may be considered in differential diagnosis for various skin disorders, including those mentioned above.

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