What is acrodermatitis enteropathica?
Acrodermatitis enteropathica is a rare genetic disorder that affects the body's ability to absorb zinc, a trace element essential for proper body function. Occurring mainly in post-weaning infants, this condition leads to severe zinc deficiency, causing skin lesions, gastrointestinal disorders, neurological problems and immune weakness.
Zinc plays a fundamental role in many biological processes: it is involved in protein synthesis, immune system function, wound healing and brain development. Prolonged zinc deficiency can therefore have serious health consequences.
In infants, the onset of symptoms often coincides with the cessation of breastfeeding, as breast milk contains a more easily absorbed form of zinc. Once weaning has taken place, the child's intestine is no longer able to absorb sufficient zinc from food, leading to the characteristic symptoms of the disease.
Although this disease is rare, it requires early diagnosis and treatment to avoid potentially serious complications. With appropriate management, patients can lead a normal life without long-term sequelae.
What are the symptoms of acrodermatitis enteropathica?
The symptoms ofacrodermatitis enteropathica are manifold, mainly affecting the skin, digestive and nervous systems. They generally appear in infants a few weeks after weaning, but can also occur later in life. Here is a detailed description of the main clinical signs:
Skin symptoms:
- Erythematous and vesicular lesions: These inflammatory lesions appear mainly around the mouth, eyes, nose, ears and genital area. They may evolve into scabs and ulcerations if left untreated.
- Alopecia: Partial or total loss of hair and eyebrows is common, giving the patient a characteristic appearance.
- Dermatitis of the extremities: painful rashes may appear on hands, feet and buttocks, sometimes accompanied by cracking and scaling.
Gastrointestinal symptoms:
- Chronic diarrhea: Zinc malabsorption leads to persistent digestive disorders, accompanied by watery, foul-smelling stools.
- Abdominal pain: Frequent abdominal cramps can interfere with eating and sleeping.
- Weight loss and stunted growth: Zinc deficiency impairs growth and physical development, which can lead to stunted growth.
Neurological and behavioural symptoms:
- Irritability and excessive crying: Infants withacrodermatitis enteropathica often exhibit marked irritability and inconsolable crying.
- Sleep disorders: Zinc deficiency can disrupt sleep and cause frequent waking.
- Slower motor and cognitive development: Prolonged zinc deficiency can affect brain development, leading to delays in the acquisition of motor and cognitive skills.
Immune symptoms:
- Recurrent infections: Zinc deficiency weakens the immune system, making the patient more vulnerable to bacterial, viral and fungal infections.
- Delayed healing: The skin takes longer to heal after an injury, increasing the risk of secondary infection.
What causes acrodermatitis enteropathica?
Acrodermatitis enteropathica is caused by a mutation in the SLC39A4 gene, located on chromosome 8. This gene codes for a protein called ZIP4, which plays an essential role in zinc absorption in the small intestine.
In people with this disease, mutation of the SLC39A4 gene leads to dysfunction of the ZIP4 protein, preventing the body from absorbing sufficient zinc from food. This chronic zinc deficiency causes the characteristic symptoms ofacrodermatitis enteropathica.
Transmission of this disease is autosomal recessive, meaning that the child must inherit two mutated copies of the gene (one from each parent) to develop the disease. If both parents are healthy carriers, the risk of transmitting the disease to their child is 25% with each pregnancy.
How is acrodermatitis enteropathica diagnosed?
The diagnosis ofacrodermatitis enteropathica is based on a combination of clinical signs, biological analyses and genetic tests.
- Clinical examination: The physician examines characteristic skin lesions, as well as other digestive and neurological symptoms. The location of lesions around body orifices (mouth, eyes, nose, anus) is a key clue to diagnosis.
- Serum zinc levels: A blood test measures zinc levels in the blood. A lower-than-normal concentration (< 70 µg/dL in children) indicates zinc deficiency, reinforcing the suspicion ofacrodermatitis enteropathica.
- Therapeutic test: Oral administration of zinc results in rapid improvement of cutaneous and gastrointestinal symptoms within a few days. This positive response is an essential diagnostic element.
- Genetic analysis: A genetic screening test can identify the SLC39A4 gene mutation and confirm the diagnosis. This test is particularly recommended for families with a history of the disease.
How is acrodermatitis enteropathica treated?
Treatment ofacrodermatitis enteropathica relies primarily on oral zinc supplementation, which must be continued for life to prevent recurrence of symptoms.
Zinc supplementation :
- The recommended daily dose depends on the patient's age and the severity of the deficiency. In infants, a dose of 1 to 3 mg/kg/day of elemental zinc is generally prescribed.
- Zinc gluconate and zinc sulfate are the most commonly used forms, as they are well absorbed by the body.
- Supplementation leads to rapid improvement in skin symptoms within 24 to 48 hours, while other symptoms gradually disappear over weeks.
Regular medical monitoring:
Regular medical monitoring is essential to adjust the zinc dose to the patient's individual needs. Periodic blood tests help to ensure that zinc levels remain within the normal range and avoid any risk of overdosing.
Zinc-rich diet:
Although supplementation is essential, a balanced diet can complement treatment. Zinc-rich foods include red meat, seafood (especially oysters), legumes, nuts and seeds.
Is acrodermatitis enteropathica hereditary?
Yes,acrodermatitis enteropathica is an autosomal recessive genetic disease. This means that a child must inherit two mutated copies of the SLC39A4 gene (one from each parent) to develop the disease.
If both parents are healthy carriers of the defective gene, the probability of transmitting the disease to their child is :
- 25%: The child inherits both mutated copies and develops the disease.
- 50 %: The child inherits only one mutated copy and becomes a healthy carrier without symptoms.
- 25%: The child inherits both normal copies of the gene and presents no risk of transmission.
For families with a history ofacrodermatitis enteropathica, genetic counseling may be offered before conception to assess risk and consider prenatal screening.
Can acrodermatitis enteropathica be prevented?
There is no specific prevention method to avoid the onset ofacrodermatitis enteropathica, as it is a genetic disease. However, certain measures can reduce the risk of complications:
- Early screening of at-risk infants: For families with a history of the disease, genetic screening can be carried out in newborns to confirm or exclude the presence of the SLC39A4 gene mutation.
- Medical follow-up at the first signs of zinc deficiency: Prompt treatment can help prevent complications and ensure normal development.
- Preventive zinc supplementation: In certain cases, preventive supplementation can be considered from birth to avoid the onset of symptoms.
