Johnson–McMillin syndrome

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Johnson–McMillin syndrome
Synonyms
Pronounce
Specialty	Medical genetics
Symptoms	Hearing loss, nail abnormalities, palmoplantar keratoderma
Complications	N/A
Onset
Duration
Types
Causes	Genetic mutation
Risks
Diagnosis	Genetic testing, clinical evaluation
Differential diagnosis
Prevention
Treatment	Supportive care, hearing aids
Medication
Prognosis
Frequency
Deaths

Johnson–McMillin syndrome is a rare genetic disorder characterized by a combination of neurological and dermatological abnormalities. It is named after the researchers who first described the condition. The syndrome is primarily associated with mutations in the GJB2 gene, which encodes the protein connexin 26.

Clinical Features

Individuals with Johnson–McMillin syndrome typically present with a range of symptoms that can vary in severity. Common clinical features include:

• Sensorineural hearing loss
• Palmoplantar keratoderma, a condition characterized by thickening of the skin on the palms and soles
• Neuropathy, which may manifest as muscle weakness or loss of sensation
• Ichthyosis, a condition that causes widespread scaling of the skin

Genetics

Johnson–McMillin syndrome is inherited in an autosomal dominant manner. This means that a single copy of the mutated gene is sufficient to cause the disorder. The GJB2 gene mutation leads to dysfunctional connexin 26 protein, which is crucial for the function of gap junctions in various tissues, including the skin and inner ear.

Diagnosis

The diagnosis of Johnson–McMillin syndrome is based on clinical evaluation, family history, and genetic testing. Audiometry is often used to assess the degree of hearing loss, while skin biopsies may be performed to examine the dermatological abnormalities. Genetic testing can confirm the presence of mutations in the GJB2 gene.

Management

There is currently no cure for Johnson–McMillin syndrome, and treatment is primarily supportive. Management strategies may include:

• Hearing aids or cochlear implants for hearing loss
• Topical treatments and emollients for skin conditions
• Physical therapy for muscle weakness and neuropathy

Prognosis

The prognosis for individuals with Johnson–McMillin syndrome varies depending on the severity of symptoms. Early diagnosis and intervention can improve the quality of life for affected individuals.

See Also

• Genetic disorder
• Sensorineural hearing loss
• Palmoplantar keratoderma
• Neuropathy
• Ichthyosis
• GJB2

External Links

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