Laryngo-onycho-cutaneous syndrome

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Laryngo-onycho-cutaneous (LOC) syndrome is a disorder that leads to abnormalities of the voicebox (laryngo-), finger- and toenails (onycho-), and skin (cutaneous). Many of the condition's signs and symptoms are related to the abnormal growth of granulation tissue in different parts of the body. This red, bumpy tissue is normally produced during wound healing and is usually replaced by skin cells as healing continues. However, in people with LOC syndrome, this tissue grows even when there is no major injury.

One of the first symptoms in infants with LOC syndrome is a hoarse cry due to ulcers or overgrowth of granulation tissue in the voicebox (the larynx). Excess granulation tissue can also block the airways, leading to life-threatening breathing problems; as a result many affected individuals do not survive past childhood.

In LOC syndrome, granulation tissue also grows in the eyes, specifically the conjunctiva, which are the moist tissues that line the eyelids and the white part of the eyes. Affected individuals often have impairment or complete loss of vision due to the tissue overgrowth.

Another common feature of LOC syndrome is missing patches of skin (cutaneous erosions). The erosions heal slowly and may become infected. People with LOC syndrome can also have malformed nails and small, abnormal teeth. The hard, white material that forms the protective outer layer of each tooth (enamel) is thin, which contributes to frequent cavities.

LOC syndrome is typically considered a subtype of another skin condition called junctional epidermolysis bullosa, which is characterized by fragile skin that blisters easily. While individuals with junctional epidermolysis bullosa can have some of the features of LOC syndrome, they do not usually have overgrowth of granulation tissue in the conjunctiva.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

LOC syndrome is caused by mutations in the LAMA3 gene, which provides instructions for making one part (subunit) of a protein called laminin 332. This protein is made up of three subunits, called alpha, beta, and gamma. The LAMA3 gene carries instructions for the alpha subunit; the beta and gamma subunits are produced from other genes.

The laminin 332 protein plays an important role in strengthening and stabilizing the skin by helping to attach the top layer of skin (the epidermis) to underlying layers. Studies suggest that laminin 332 is also involved in wound healing. Additionally, researchers have proposed roles for laminin 332 in the clear outer covering of the eye (the cornea) and in the development of tooth enamel.

The mutations involved in LOC syndrome alter the structure of one version of the alpha subunit of laminin 332 (called alpha-3a). Laminins made with the altered subunit cannot effectively attach the epidermis to underlying layers of skin or regulate wound healing. These abnormalities of laminin 332 cause the cutaneous erosions and overgrowth of granulation tissue that are characteristic of LOC syndrome. The inability of laminin 332 to perform its other functions leads to the nail and tooth abnormalities that occur in this condition.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

LOC syndrome is a rare disorder that primarily affects families of Punjabi background from India and Pakistan, although the condition has also been reported in one family from Iran.

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.

Skin ulcer · Very frequent (99-80%)

A discontinuity of the skin exhibiting complete loss of the epidermis and often portions of the dermis and even subcutaneous fat.

Subglottic stenosis · Very frequent (99-80%)

Abnormal blistering of the skin · Frequent (79-30%)

The presence of one or more bullae on the skin, defined as fluid-filled blisters more than 5 mm in diameter with thin walls.

Abnormality of the periungual region · Frequent (79-30%)

An abnormality of the region around the nails of the fingers or toes.

Carious teeth · Frequent (79-30%)

Caries is a multifactorial bacterial infection affecting the structure of the tooth. This term has been used to describe the presence of more than expected dental caries.

Corneal erosion · Frequent (79-30%)

An erosion or abrasion of the cornea's outermost layer of epithelial cells.

Corneal ulceration · Frequent (79-30%)

Disruption of the epithelial layer of the cornea with involvement of the underlying stroma.

Delayed eruption of teeth · Frequent (79-30%)

Delayed tooth eruption, which can be defined as tooth eruption more than 2 SD beyond the mean eruption age.

Other findings in the same source

From: Orphanet

Additional reported features include Enamel hypoplasia (Frequent (79-30%)); Exuberant granulation tissue (Frequent (79-30%)); Fragile skin (Frequent (79-30%)); Hoarse voice (Frequent (79-30%)); Inspiratory stridor (Frequent (79-30%)); Microdontia (Frequent (79-30%)); Nail dystrophy (Frequent (79-30%)); Oral mucosal blisters (Frequent (79-30%)); Skin erosion (Frequent (79-30%)); Symblepharon (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 Laryngo-onycho-cutaneous syndrome 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 Laryngo-onycho-cutaneous syndrome. 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.