Familial pityriasis rubra pilaris

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Familial pityriasis rubra pilaris is a rare genetic condition that affects the skin. The name of the condition reflects its major features: The term "pityriasis" refers to scaling; "rubra" means redness; and "pilaris" suggests the involvement of hair follicles in this disorder. Affected individuals have a salmon-colored skin rash covered in fine scales. This rash occurs in patches all over the body, with distinct areas of unaffected skin between the patches. Affected individuals also develop bumps called follicular keratoses that occur around hair follicles. The skin on the palms of the hands and soles of the feet often becomes thick, hard, and callused, a condition known as palmoplantar keratoderma.

Researchers have distinguished six types of pityriasis rubra pilaris based on the features of the disorder and the age at which signs and symptoms appear. The familial form is usually considered part of type V, which is also known as the atypical juvenile type. People with familial pityriasis rubra pilaris typically have skin abnormalities from birth or early childhood, and these skin problems persist throughout life.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

In most cases of pityriasis rubra pilaris, the cause of the condition is unknown. However, mutations in the CARD14 gene have been found to cause the familial form of the disorder in a few affected families. The CARD14 gene provides instructions for making a protein that turns on (activates) a group of interacting proteins known as nuclear factor-kappa-B (NF-κB). NF-κB regulates the activity of multiple genes, including genes that control the body's immune responses and inflammatory reactions. It also protects cells from certain signals that would otherwise cause them to self-destruct (undergo apoptosis).

The CARD14 protein is found in many of the body's tissues, but it is particularly abundant in the skin. NF-κB signaling appears to play an important role in regulating inflammation in the skin. Mutations in the CARD14 gene lead to overactivation of NF-κB signaling, which triggers an abnormal inflammatory response. Researchers are working to determine how these changes lead to the specific features of familial pityriasis rubra pilaris.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

Familial pityriasis rubra pilaris usually has an autosomal dominant inheritance pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. Affected individuals usually inherit the condition from one affected parent. However, the condition is said to have incomplete penetrance because not everyone who inherits the altered gene from a parent develops the condition's characteristic skin abnormalities.

The other types of pityriasis rubra pilaris are sporadic, which means they occur in people with no history of the disorder in their family.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

Familial pityriasis rubra pilaris is a rare condition. Its incidence is unknown, although the familial form appears to be the least common type of pityriasis rubra pilaris.

Understanding terms used in the source

These definitions explain medical words used above. A definition is not evidence that another condition is present, and it does not predict how a symptom will develop. Ask the clinician which terms apply to the actual examination or test result.

Abnormal inflammatory response

Any anomaly of the inflammatory response, a response to injury or infection characterized by local vasodilation, extravasation of plasma into intercellular spaces and accumulation of white blood cells and macrophages.

Autosomal dominant inheritance

A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in heterozygotes. In the context of medical genetics, an autosomal dominant disorder is caused when a single copy of the mutant allele is present. Males and females are affected equally, and can both transmit the disorder with a risk of 50% for each child of inheriting the mutant allele.

Palmoplantar keratoderma

Abnormal thickening of the skin of the palms of the hands and the soles of the feet.

Unaffected

This term applies to a family member in whom the diagnosis that is the primary focus of investigation is excluded.

Affected

This term applies to a family member who is diagnosed with the same condition as the individual who is the primary focus of investigation (the proband).

Which doctor should you see?

The suggested department for discussing Familial pityriasis rubra pilaris is Clinical Genetics, with a clinical geneticist as the relevant type of clinician. Paediatrician (children) or physician (adults), with clinical geneticist referral.

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.

• Does the exact genetic or chromosome finding explain the observed features?
• Would a genetic counsellor help the family understand the result?
• Which organ-specific assessments are appropriate for this particular diagnosis?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Familial pityriasis rubra pilaris. 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.