Xeroderma pigmentosum

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Xeroderma pigmentosum, commonly known as XP, is an inherited condition characterized by an extreme sensitivity to ultraviolet radiation (UVR), which is present in sunlight and may also be found in some types of artificial lighting. This condition mostly affects the eyes and areas of skin exposed to the sun. Xeroderma pigmentosum is associated with an increased risk of UVR-induced cancers. People with this condition often experience premature aging. Some affected individuals also have problems involving the nervous system.

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. The sunburn causes redness and blistering that can last for weeks. However, some children with xeroderma pigmentosum can tan normally.

By age 2, almost all children with xeroderma pigmentosum develop freckling of the skin in sun-exposed areas (such as the face, arms, and lips); this type of freckling rarely occurs in young children without the disorder. In affected individuals, exposure to sunlight often causes dry skin (xeroderma) and changes in skin coloring (pigmentation). This combination of features gives the condition its name.

People with xeroderma pigmentosum are 10,000 times more likely to develop non-melanoma skin cancer and up to 2,000 times more likely to develop melanoma skin cancer compared to individuals without this condition. The types of skin cancer that can develop include basal cell carcinoma, squamous cell carcinoma, and melanoma. Most commonly, the first skin cancer appears in affected individuals before age 10.

Without protection from the sun and other sources of UVR, most people with xeroderma pigmentosum develop multiple skin cancers during their lifetime. These cancers occur most often on portions of the body that are exposed to the sun, including the face, the lips, the eyelids, the surface of the eyes, the scalp, and the tip of the tongue. Studies suggest that people with xeroderma pigmentosum may also have an increased risk of some internal cancers, including brain tumors, thyroid cancer, and blood cancers. Additionally, affected individuals who smoke cigarettes have a significantly increased risk of lung cancer.

The eyes of people with xeroderma pigmentosum may be painfully sensitive to UVR (photophobia). If the eyes are not protected from UVR, they may become bloodshot and irritated, and the clear front covering of the eyes (the cornea) may become cloudy. In some people, the eyelashes fall out and the eyelids may be thin and turn abnormally inward or outward. In addition to an increased risk of cancer on the surface of the eye, xeroderma pigmentosum is associated with noncancerous growths on the eye. Many of these eye abnormalities can impair vision.

About 30 percent of people with xeroderma pigmentosum develop progressive neurological abnormalities in addition to problems involving the skin and eyes. These abnormalities can include hearing loss, poor coordination, difficulty walking, movement problems, loss of intellectual function, difficulty swallowing and talking, and seizures. When these neurological problems occur, they tend to worsen with time.

Individuals with xeroderma pigmentosum may experience early menopause.

Researchers have identified at least eight genetic forms of xeroderma pigmentosum: complementation group A (XP-A) through complementation group G (XP-G), plus a variant type (XP-V). The types are distinguished by their genetic cause. All of the types increase the risk of skin cancer, although some are more likely than others to be associated with neurological abnormalities.

ORPHANET DEFINITION Xeroderma pigmentosum (XP) is a rare genodermatosis characterized by extreme sensitivity to ultraviolet (UV)-induced changes in the skin and eyes, and multiple skin cancers. It is subdivided into 8 complementation groups, according to the affected gene: classical XP (XPA to XPG) and XP variant (XPV).

Inheritance

From: MedlinePlus Genetics, National Library of Medicine

Autosomal recessive

Frequency in the source

From: MedlinePlus Genetics, National Library of Medicine

Point prevalence: 1-9 / 1 000 000; United States; Value and class. Point prevalence: 1-9 / 100 000; Japan; Value and class. Prevalence at birth: 1-9 / 1 000 000; United Kingdom; Value and class. Prevalence at birth: 1-9 / 1 000 000; Netherlands; Value and class.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Abnormality of the dentition · Very frequent (99-80%)

Any abnormality of the teeth.

Arthralgia · Very frequent (99-80%)

Joint pain.

Cognitive impairment · Very frequent (99-80%)

Abnormal cognition is characterized by deficits in thinking, reasoning, or remembering.

Conjunctival telangiectasia · Very frequent (99-80%)

The presence of small (ca. 0.5-1.0 mm) dilated blood vessels near the surface of the mucous membranes of the conjunctiva.

Cutaneous photosensitivity · Very frequent (99-80%)

An increased sensitivity of the skin to light. Photosensitivity may result in a rash upon exposure to the sun (which is known as photodermatosis). Photosensitivity can be diagnosed by phototests in which light is shone on small areas of skin.

Developmental regression · Very frequent (99-80%)

Loss of developmental skills, as manifested by loss of developmental milestones.

Dry skin · Very frequent (99-80%)

Skin characterized by the lack of natural or normal moisture.

EEG abnormality · Very frequent (99-80%)

Abnormality observed by electroencephalogram (EEG), which is used to record of the brain's spontaneous electrical activity from multiple electrodes placed on the scalp.

Other findings in the same source

From: Orphanet

Additional reported features include Failure to thrive (Very frequent (99-80%)); Fatigue (Very frequent (99-80%)); Fever (Very frequent (99-80%)); Freckling (Very frequent (99-80%)); Hypogonadism (Very frequent (99-80%)); Optic atrophy (Very frequent (99-80%)); Poikiloderma (Very frequent (99-80%)); Telangiectasia (Very frequent (99-80%)); Telangiectasia of the skin (Very frequent (99-80%)); Thickened skin (Very frequent (99-80%)). This is a selected summary, not a complete description of the condition.

When it may begin

From: MedlinePlus Genetics, National Library of Medicine

All ages

Inheritance in the source

From: MedlinePlus Genetics, National Library of Medicine

Autosomal recessive

Frequency and the population described

From: MedlinePlus Genetics, National Library of Medicine

Point prevalence: 1-9 / 1 000 000; United States; Value and class. Point prevalence: 1-9 / 100 000; Japan; Value and class. Prevalence at birth: 1-9 / 1 000 000; United Kingdom; Value and class. Prevalence at birth: 1-9 / 1 000 000; Netherlands; Value and class.

Understanding the inheritance label

From: MedlinePlus Genetics

An autosomal recessive pattern usually involves disease-causing changes in both copies of a gene. Parents may each carry one altered copy without having the condition themselves. A genetic counsellor can explain carrier testing and reproductive implications using the actual laboratory findings, rather than the condition name alone.

Which doctor should you see?

The suggested department for discussing Xeroderma pigmentosum is Dermatology, with a dermatologist as the relevant type of clinician. Dermatologist; paediatric services for children as appropriate.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Which features of the skin, hair or nails distinguish the possibilities?
• Would photographs over time help document the changes?
• What should be expected from treatment, and how will irritation or other adverse effects be managed?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Xeroderma pigmentosum. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.