What Is Gorlin Syndrome

There is a helpful mnemonic to help understand the primary features of Gorlin Syndrome: 

• Genes went awry, causing various issues
• Overactive cell growth and development
• Risk of skin cancer
• Large forehead and wide-set eyes
• Increased sensitivity to light, protect that skin!
• Numerous skeletal abnormalities

Overview

Gorlin syndrome (GS) is a rare genetic condition that predominantly affects the skin and bones and several other organs and bodily systems. Those with Gorlin syndrome have an increased risk of developing skin cancers as well as other tumours. It is caused by a mutation in a tumour suppressor gene; tumour suppressor genes encode proteins that prevent and fight against the development of tumours and cancers.1 GS is an incurable genetic disease, but accurate information and management can help in minimising its impact and protecting against the development of cancers.

GS has also been referred to as Gorlin-Goltz syndrome, basal cell nevus syndrome (BCNS), or nevoid basal cell carcinoma syndrome. It is an autosomal dominant disorder, meaning that if the patient inherits just one copy of the faulty gene, they will have the syndrome even if the other copy is healthy.1 GS is characterised by numerous basal cell carcinomas (BCCs) and anomalies in the skeleton, eyes, and nervous system.1 Beginning in early childhood, neoplasms (new and abnormal growths often associated with cancer) will begin to develop.¹ The most common form of cancer found in those with GS is BCC, which is also the most common type of skin cancer. Basal cell carcinomas often start to appear in people with this syndrome in adolescence. Usually, these tumours develop on the back, chest, and face.² 

Each affected individual has a different lifetime risk of developing basal cell carcinomas. While some individuals with the disease may acquire many basal cell carcinomas, others may never develop any. People with lighter skin are more prone to acquiring basal cell carcinomas than those with a darker complexion.² There are treatments available that attempt to lower the number of carcinomas. Most GS sufferers also grow keratocystic odontogenic tumours (KCOTs) which are considered benign (noncancerous) tumours.1,2 Most KCOTs develop throughout adolescence, and new tumours continue to develop until patients are aged 30; they rarely manifest in adults.² These benign growths may result in uncomfortable face swelling and tooth displacement without treatment.^1,2

GS was first recorded in 1894 but was not fully recognised until 1960 by Gorlin and Goltz.² A collection of discoveries consistent with the syndrome in mummies dating as far back as 1,000 BC indicates this syndrome was present in Dynastic Egyptian times. The prevalence is thought to be 1 in 40,000-60,000 but varies significantly by region.^1,2 

According to research, the condition affects one in 55,600 persons in England's North West. Italy appears to have a lower incidence of the disease than Australia (1/164,000) and the United Kingdom (1/256,000).^2,3 

Causes of gorlin syndrome

GS results from mutations in a gene called PTCH1, which encodes a protein called patched-1.² The patched-1 protein is a receptor and other proteins, known as ligands, fit into specific locations on receptor proteins like keys into locks. Once ligands bind to the receptor, signals are produced that affect how cells develop and function. The ligand for the patched-1 receptor is a protein named Sonic Hedgehog (SHH).² Unless SHH is attached, Patched-1 inhibits cell division and development (proliferation).² As a tumour suppressor gene, PTCH1 prevents uncontrollable or excessively rapid cell proliferation. If the gene is mutated, then fully functional patched-1 proteins cannot be produced, and cell proliferation is uninhibited, increasing the likelihood of tumour formation. 

It is impossible to successfully inhibit cell growth and division with a damaged or absent patched-1 receptor. As a result, cells multiply uncontrollably to produce the tumours distinctive to GS.

80% of patients who present with a KCOT were found to have biallelic somatic PTCH1 mutations.³ Two rare related genes, SUFU and PTCH2, have also been implicated in GS.3 SUFU inhibits the Hedgehog (Hh) signalling pathway, and this loss of function causes the Hh signalling pathway to be permanently activated. PTCH2 is closely related to PTCH1.3 Patients with the PTCH2 mutation are more likely to have milder symptoms than those with the PTCH1 mutation.³

Signs and symptoms of gorlin syndrome

The following are the most common clinical manifestations of GS: REF

• Odontogenic keratocyst
• Basal cell carcinoma (affects the hands, neck, and face)
• Tiny indentations on the palm and sole of the feet (Palmar and plantar pits)⁴
• Skeletal issues with the ribs, spine, or skull¹

Less frequent symptoms include:

• Abnormally large head (macrocephaly)^3,4
• Cleft palate or lip^1,3
• Wide eyes (hypertelorism)¹ 
• Crossed eyes (strabismus)²
• Multiple melanocytic nevi¹
• Large forehead (frontal bossing)⁴
• Smaller shoulder blades (Sprengel deformity)¹
• Abnormality in the chest wall's structure or form (pectus deformity)¹
• Brain tumours, such as medulloblastoma or meningioma²
• Webbed fingers or toes
• Growths in the ovaries (fibromas)³

Management and treatment

• Patients with GS need comprehensive treatment due to the wide range of symptoms. Basal cell carcinoma (BCC) is the most frequently seen condition resulting from GS. There are three categories of therapeutic techniques for treating BCC in GS: surgical, non-surgical, and molecular pathogenesis-based treatments.

Surgical procedure

In GS, Mohs micrographic surgery is advised, especially for high-risk recurrent tumours in the face or other high-risk areas.¹ This method has a 99% initial BCC cure rate and a 99.4% recurrent BCC cure rate.⁵ In some instances of small, primary, non-aggressive BCCs located in low-risk recurrence locations, such as the trunk or limbs, curettage, electrocoagulation, and cryotherapy have been advised.^1,5 Ablative CO2 laser treatment is an additional option for superficial BCC.⁵

Non-surgical therapy

A popular and well-known treatment for BCC is photodynamic therapy (PDT).^5,6 Aminolevulinic acid and methyl aminolevulinate are both utilised as photosensitisers in Europe.⁵ In individuals with GS, PDT with methyl aminolevulinate is regarded as efficient and secure, and the procedure can be utilised to treat multiple BCCs dispersed over broad body areas. Treating superficial BCCs with immunotherapy with imiquimod 5% cream is also approved.⁵ 

Topical chemotherapy with 5-fluorouracil (5 FU) 5% can be used for BCC in facial, thin, low-risk tumours.⁵ Tretinoin 0.1% cream or ingenol mebutate can be utilised to treat severely afflicted areas that have been ineffective to prior treatments.⁵

Molecular pathogenesis-driven treatment

Vismodegib has received U.S. Food and Drug Administration (FDA) approval for the therapeutic care of locally or regionally advanced BCCs for patients not suited for radiation or surgery.⁵ Itraconazole and arsenic trioxide have been shown to block the SHH system and reduce tumour growth in animal models of medulloblastoma and BCC.⁵

Diagnosis

The diagnostic methods typically include the following:

• Family history and clinical examination: Where the patient's family has a history of the illness, a thorough examination should be performed at birth or soon after to check for any abnormalities such as a large head, frontal and temporal bossing, cleft palate, eye anomalies, bifid ribs, or vertebral anomalies. A neurological examination is encouraged every six months to check for impairments brought on by medulloblastomas.  
• Genetic testing: DNA tests, which directly examine the gene mutation, may confirm that the patient has GS. Families are encouraged to participate in routine screening.¹ DNA tests can identify whether or not someone in a family has inherited the illness by tracking chromosome 9, which includes the damaged gene, or by conducting a direct study of the mutation that causes the condition in a particular family.¹ 
• Radiographic examination: Depending on the circumstances, imaging studies may include X-ray, echocardiography, abdominal ultrasonography, dental radiography, and skeletal survey.⁴
• Laboratory tests: Patients with suspected GS should have a biopsy with samples taken from numerous suspect skin lesions²
• Antenatal diagnosis: Antenatal diagnosis can avert future complications. Even though developmental problems are not prevalent, prenatal ultrasound scans can help detect them.²

FAQs

How can I prevent gorlin syndrome?

Since GS is a genetic illness, prevention is not possible. Inherited genetic mutations are the root cause. Patients with GS should adjust their lifestyles and receive medical care as preventive measures. The use of sunscreen consistently, vitamin D supplements, and avoiding exposure to ionising radiation are all recommended to patients. A dermatologist should examine your skin annually to look for any symptoms of skin cancer. However, genetic counselling can assist in determining your risk and offer advice on family planning alternatives if you have a history of GS in your family.⁵

How common is gorlin syndrome?

According to estimates, GS affects between 1 in 30,000 and 1 in 256,000 people.

Who is at risk of GS?

The main risk factor for developing this syndrome is having a parent who has the condition because it is a genetic disorder. A 50% possibility exists for each child to inherit the faulty gene and develop GS if one parent has the condition.

When should I see a doctor?

You should get medical advice from a dermatologist or genetic counsellor if you have a family history of GS or exhibit symptoms of basal cell carcinomas, jaw cysts, or skeletal abnormalities. 

Summary

GS is an inherited genetic disease caused by a mutated tumour suppressor gene, resulting in an increased risk of developing tumours, particularly BCCs. GS patients may also exhibit various skeletal and neurologic abnormalities. GS is primarily diagnosed through genetic testing to identify the mutated gene. Radiography and laboratory tests are used to support the diagnosis and assess the severity of symptoms. Patients with GS must avoid UV radiation and wear high-factor suncream to reduce the risk of BCCs. There have yet to be any significant clinical trials on how to treat these patients because the syndrome is so uncommon. However, many persons with this disease have a high quality of life by adhering to medical advice.