Summary about Disease
Zinc transporter SLC39A4 deficiency, also known as Acrodermatitis Enteropathica (AE), is a rare autosomal recessive metabolic disorder. It is characterized by impaired zinc absorption due to a defect in the SLC39A4 (also known as ZIP4) protein, which is essential for intestinal zinc uptake. This deficiency leads to a variety of symptoms primarily affecting the skin, gastrointestinal tract, and immune system. Without proper treatment with zinc supplementation, it can be life-threatening.
Symptoms
Symptoms typically manifest in infancy after weaning from breast milk (which contains zinc) or when formula with inadequate zinc is used. Key symptoms include:
Skin: Erythematous, scaling, and crusting skin lesions, particularly around the mouth, nostrils, eyes, anus, fingers, and toes. These lesions can resemble eczema or psoriasis.
Gastrointestinal: Chronic or intermittent diarrhea, vomiting, and abdominal pain.
Hair: Alopecia (hair loss), sparse eyebrows and eyelashes.
Nails: Paronychia (inflammation around the nail), nail dystrophy.
Immune System: Increased susceptibility to infections (bacterial, fungal, viral).
Growth: Growth retardation and failure to thrive.
Mood: Irritability and apathy.
Eyes: Photophobia (sensitivity to light).
Causes
Acrodermatitis Enteropathica is caused by mutations in the SLC39A4 gene. This gene provides instructions for making the ZIP4 protein, a zinc transporter located on the surface of intestinal cells. ZIP4 is crucial for absorbing zinc from the diet. Mutations in *SLC39A4* disrupt the production or function of ZIP4, leading to impaired zinc absorption and subsequent zinc deficiency. It is inherited in an autosomal recessive manner, meaning both parents must carry a copy of the mutated gene for their child to be affected.
Medicine Used
The primary treatment for Acrodermatitis Enteropathica is zinc supplementation. This is typically administered orally in the form of zinc sulfate, zinc acetate, or zinc gluconate. The dosage varies depending on the individual's age, weight, and severity of symptoms. Lifelong zinc supplementation is usually required to maintain adequate zinc levels and prevent recurrence of symptoms. In some cases, topical treatments (e.g., emollients, corticosteroids) may be used to manage skin lesions.
Is Communicable
No, Acrodermatitis Enteropathica is not communicable. It is a genetic disorder caused by a gene mutation and cannot be spread from person to person.
Precautions
The main precautions for individuals with Acrodermatitis Enteropathica and their families are:
Consistent Zinc Supplementation: Adherence to the prescribed zinc supplementation regimen is crucial. Missed doses can lead to recurrence of symptoms.
Dietary Considerations: While zinc supplementation is the cornerstone of treatment, a balanced diet with adequate protein intake can support overall health.
Infection Prevention: Due to impaired immune function, individuals with AE are more susceptible to infections. Good hygiene practices (e.g., handwashing) and avoiding contact with sick individuals are important.
Monitoring for Side Effects: Monitor for potential side effects of zinc supplementation, such as gastrointestinal upset.
Genetic Counseling: Genetic counseling is recommended for families with a history of AE to assess the risk of having affected children.
How long does an outbreak last?
Without treatment, an "outbreak" of Acrodermatitis Enteropathica symptoms can be chronic and persistent. The symptoms will continue as long as the zinc deficiency persists. With consistent zinc supplementation, the symptoms typically resolve within days to weeks. However, if zinc supplementation is stopped or inadequate, the symptoms will return. Therefore, there is no defined "outbreak" period, but rather a chronic condition managed by ongoing zinc replacement.
How is it diagnosed?
Diagnosis typically involves:
Clinical Evaluation: Based on the characteristic skin lesions, gastrointestinal symptoms, and other features.
Serum Zinc Levels: Low serum zinc levels are a key diagnostic indicator. However, it's important to note that serum zinc levels can be affected by other factors (e.g., infection, inflammation), so repeat testing may be needed.
Alkaline Phosphatase Levels: Low alkaline phosphatase levels can be suggestive of zinc deficiency, as zinc is a cofactor for this enzyme.
Genetic Testing: Confirmation of the diagnosis is made by identifying mutations in the SLC39A4 gene through genetic testing.
Skin Biopsy: A skin biopsy may be performed to examine the characteristic histological features of AE, but it is not always necessary for diagnosis.
Timeline of Symptoms
Infancy (after weaning): Symptoms typically appear after cessation of breastfeeding or when switched to a formula with inadequate zinc.
Initial Symptoms: Often include diarrhea, irritability, and skin lesions, particularly around the mouth and diaper area.
Progression (without treatment): Skin lesions spread and worsen, hair loss develops, growth slows, and immune function becomes increasingly compromised, leading to frequent infections.
With Treatment (zinc supplementation): Improvement is typically seen within days to weeks, with resolution of skin lesions, improved gastrointestinal function, and catch-up growth.
Important Considerations
Early Diagnosis and Treatment: Early diagnosis and prompt initiation of zinc supplementation are essential to prevent severe complications and ensure optimal growth and development.
Lifelong Management: Acrodermatitis Enteropathica requires lifelong zinc supplementation.
Adherence to Treatment: Strict adherence to the prescribed zinc supplementation regimen is crucial to prevent recurrence of symptoms.
Monitoring: Regular monitoring of serum zinc levels and clinical assessment are important to ensure adequate zinc levels and detect any potential side effects of treatment.
Genetic Counseling: Genetic counseling is recommended for families with a history of AE to understand the inheritance pattern and assess the risk of having affected children.
Differential Diagnosis: It's important to differentiate AE from other conditions with similar symptoms, such as eczema, psoriasis, and other nutritional deficiencies.