Gorlin syndrome

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Gorlin syndrome, also known as nevoid basal cell carcinoma syndrome, is a condition that affects many areas of the body and increases the risk of developing various cancerous and noncancerous tumors.

In people with Gorlin syndrome, the type of cancer diagnosed most often is basal cell carcinoma, which is the most common form of skin cancer. Individuals with Gorlin syndrome typically begin to develop basal cell carcinomas during adolescence or early adulthood. These cancers occur most often on the face, chest, and back. The number of basal cell carcinomas that develop during a person's lifetime varies among affected individuals. Some people with Gorlin syndrome never develop any basal cell carcinomas, while others may develop thousands of these cancers. Individuals with lighter skin are more likely to develop basal cell carcinomas than are people with darker skin. The number of carcinomas may be reduced with ongoing treatment.

Most people with Gorlin syndrome also develop noncancerous (benign) tumors of the jaw, called keratocystic odontogenic tumors. These tumors usually first appear during adolescence, and new tumors form until about age 30. Keratocystic odontogenic tumors rarely develop later in adulthood. If untreated, these tumors may cause painful facial swelling and tooth displacement.

Individuals with Gorlin syndrome have a higher risk than the general population of developing other tumors. A small proportion of affected individuals develop a brain tumor called medulloblastoma during childhood. A type of benign tumor called a fibroma can occur in the heart or in a woman's ovaries. Heart (cardiac) fibromas often do not cause any symptoms, but they may obstruct blood flow or cause irregular heartbeats (arrhythmia). Ovarian fibromas are not thought to affect a woman's ability to have children (fertility).

Other features of Gorlin syndrome include small depressions (pits) in the skin of the palms of the hands and soles of the feet; an unusually large head size (macrocephaly) with a prominent forehead; and skeletal abnormalities involving the spine, ribs, or skull. These signs and symptoms are typically apparent from birth or become evident in early childhood.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Mutations in the PTCH1 gene are the main cause Gorlin syndrome. This gene provides instructions for making a protein called patched-1, which functions as a receptor. Receptor proteins have specific sites into which certain other proteins, called ligands, fit like keys into locks. Together, ligands and their receptors trigger signals that affect cell development and function. A protein called Sonic Hedgehog is the ligand for the patched-1 receptor. Patched-1 blocks cell growth and division (proliferation) until Sonic Hedgehog is attached.

The PTCH1 gene is a tumor suppressor gene, which means it stops cells from proliferating too rapidly or in an uncontrolled way. Mutations in this gene prevent the production of patched-1 or lead to the production of an abnormal version of the receptor. An altered or missing patched-1 receptor cannot effectively suppress cell growth and division. As a result, cells proliferate uncontrollably to form the tumors that are characteristic of Gorlin syndrome. It is less clear how PTCH1 gene mutations cause the other signs and symptoms related to this condition.

The characteristic features of Gorlin syndrome can also be associated with a chromosomal change called a 9q22.3 microdeletion, in which a small piece of chromosome 9 is deleted in each cell. This deletion includes the segment of chromosome 9 that contains the PTCH1 gene, and as a result, people with a 9q22.3 microdeletion are missing one copy of this gene. Loss of this gene underlies the signs and symptoms of Gorlin syndrome in people with 9q22.3 microdeletions. Affected individuals also have features that are not typically associated with Gorlin syndrome, including delayed development, intellectual disability, overgrowth of the body (macrosomia), and other physical abnormalities. Researchers believe that these other signs and symptoms may result from the loss of additional genes in the deleted region of chromosome 9.

Mutations in the PTCH1 gene account for 50 to 85 percent of cases of Gorlin syndrome, while mutations in other genes, some known and some unidentified, are responsible for the remaining cases.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

Gorlin syndrome is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the condition. In most cases, an affected person inherits the mutation from one affected parent. Other cases result from new mutations in the gene and occur in people with no history of the disorder in their family.

Having one mutated copy of the PTCH1 gene in each cell is enough to cause the features of Gorlin syndrome that are present early in life, including macrocephaly and skeletal abnormalities. For basal cell carcinomas and other tumors to develop, a mutation in the second copy of the PTCH1 gene must also occur in certain cells during the person's lifetime. Most people who are born with one PTCH1 gene mutation eventually acquire a second mutation in some cells and consequently develop various types of tumors.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

Gorlin syndrome affects an estimated 1 in 31,000 people. While more than 1 million new cases of basal cell carcinoma are diagnosed each year in the United States, fewer than 1 percent of these skin cancers are related to Gorlin syndrome.

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.

Cerebral calcification · Very frequent (99-80%)

The presence of calcium deposition within the cerebrum.

Melanocytic nevus · Very frequent (99-80%)

A oval and round, colored (usually medium-to dark brown, reddish brown, or flesh colored) lesion. Typically, a melanocytic nevus is less than 6 mm in diameter, but may be much smaller or larger.

Neoplasm · Very frequent (99-80%)

An organ or organ-system abnormality that consists of uncontrolled autonomous cell-proliferation which can occur in any part of the body as a benign or malignant neoplasm (tumor).

Plantar pits · Very frequent (99-80%)

The presence of multiple pits (small, pinpoint-large indentations on the surface of the skin) located on the skin of sole of foot.

Palmar pits · Very frequent (99-80%)

Abnormal rib morphology · Frequent (79-30%)

An anomaly of the rib.

Abnormality of the neck · Frequent (79-30%)

An abnormality of the neck.

Anterior rib cupping · Frequent (79-30%)

Wide, concave anterior rib end.

Other findings in the same source

From: Orphanet

Additional reported features include Basal cell carcinoma (Frequent (79-30%)); Bifid ribs (Frequent (79-30%)); Brachydactyly (Frequent (79-30%)); Calcification of falx cerebri (Frequent (79-30%)); Macrocephaly (Frequent (79-30%)); Odontogenic keratocysts of the jaw (Frequent (79-30%)); Rib fusion (Frequent (79-30%)); Scoliosis (Frequent (79-30%)); Vertebral fusion (Frequent (79-30%)); Vertebral wedging (Frequent (79-30%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Gorlin syndrome 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

Where the source describes treatments, these are an overview of possible care, not a prescription for an individual. Ask which option applies to the confirmed diagnosis, what benefit is expected, what adverse effects to watch for and how progress will be assessed. Availability, approvals and local practice can differ from the country described in the source.

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.