Keratitis–ichthyosis–deafness syndrome

Overview

Keratitis–ichthyosis–deafness (KID) syndrome is a rare congenital disorder that primarily affects the skin, eyes, and hearing. Individuals with KID syndrome present with a triad of symptoms: keratitis (inflammation of the cornea), ichthyosis (scaly, thickened skin), and sensorineural deafness (hearing loss due to inner ear or nerve damage). The syndrome typically manifests in early infancy or childhood and may progressively worsen over time. In addition to the core symptoms, affected individuals may experience increased susceptibility to infections and a heightened risk of developing squamous cell carcinoma of the skin.

Causes

KID syndrome is most often caused by mutations in the GJB2 gene, which encodes the protein connexin 26. This protein plays a critical role in cell communication by forming gap junctions, which are essential for the function of the skin, inner ear, and cornea. The disorder is typically inherited in an autosomal dominant pattern, although some sporadic (de novo) cases occur without a family history. Mutations in GJB2 disrupt normal cellular communication and result in the characteristic features of KID syndrome.

Symptoms

The clinical features of KID syndrome can vary in severity but generally include:

• Keratitis: Chronic inflammation of the cornea, which can lead to photophobia, corneal opacities, and vision loss over time

• Ichthyosis-like skin abnormalities: Thick, dry, scaly, or red patches of skin, often present at birth or appearing shortly afterward

• Sensorineural deafness: Moderate to profound hearing loss, typically present from birth

Other features may include:

• Abnormal hair growth or sparse hair

• Nail dystrophy (abnormally formed nails)

• Dental anomalies

• Increased risk of bacterial, fungal, and viral skin infections

• Elevated risk of squamous cell carcinoma in the skin or mucous membranes

Diagnosis

Diagnosis of KID syndrome is based on clinical findings and confirmed by genetic testing. Key diagnostic steps include:

• Comprehensive physical examination focusing on skin, eyes, and ears

• Ophthalmologic evaluation to detect corneal inflammation or damage

• Hearing tests (audiometry) to assess the degree of hearing loss

• Skin biopsy in uncertain cases to rule out other skin disorders

• Genetic testing to identify mutations in the GJB2 gene

Treatment

There is no cure for KID syndrome, and treatment focuses on managing symptoms and preventing complications. A multidisciplinary approach is essential and may include:

• Skin care: Use of emollients, keratolytics, and topical antibiotics or antifungals to manage skin scaling and infections

• Ophthalmologic care: Lubricating eye drops, anti-inflammatory medications, and regular monitoring by an eye specialist

• Hearing support: Hearing aids or cochlear implants to improve auditory function

• Infection control: Prompt treatment of skin infections and routine hygiene practices

• Oncology screening: Regular skin exams to detect early signs of skin cancer

• Speech and developmental therapy for communication support

Prognosis

The prognosis for individuals with KID syndrome varies depending on the severity of symptoms and the effectiveness of management. While many affected individuals live into adulthood, quality of life can be significantly impacted by progressive vision loss, hearing impairment, and recurrent infections. Early diagnosis, regular monitoring, and a coordinated care plan can help manage complications and improve outcomes. Vigilant cancer screening is especially important due to the increased risk of squamous cell carcinoma.