Acrodermatitis enteropathica.
Incidence
It is an autosomal recessive inheritance condition.
Clinical Characteristics
This condition is an inborn error of metabolism resolving in zinc malabsorption and deficiency. The symptoms usually develop after the neonatal period in exclusively breast-fed infants after weaning, due to a supposed zinc transport ligand in breast milk. The clinical characteristics are hyperkeratotic dermatitis, especially in childhood, with acral and orificial vesiculobullous, pustular and eczematoid skin lesions. There are recurrent infections of the skin and mucous membranes with candida albicans, bacteria or both. There is anorexia, failure to thrive, esophagitis, fine brittle hair with hair loss or alopecia, paronychia, ocular lesions such as blepharitis, conjunctivitis, corneal opacities and linear epithelial erosions. There is diarrhea or loose stools, emotional disturbances and often tremor. The classical triada of dermatitis, alopecia, and intractable diarrhea is present in only 20 % of cases. CNS symptoms of depression, apathy, tremor and ataxia that may be present in childhood or adolescence. Eye symptoms as nystagmus, photophobia and night blindness, growth retardation, infections and pica may be present in childhood or adolescence. Delayed puberty and hypogonadism can be seen in adolescence. In the laboratory there is low serum zinc. There is also low alkaline phosphatase levels because it is a zinc dependent enzyme. Serum zinc is especially low in infancy but may be normal in childhood or adolescence. Blood ammonia can be normal or mildly elevated. There is dramatic clinical response to zinc therapy. There is impaired enteral absorption of linoleic acid and also low urinary zinc levels. The mutation affect the zinc transport in human intestinal biopsies. The mutation affects also zinc metabolism in human fibroblasts. Biopsy of small bowel show loss of villous architecture and flattening of villi and cuboid intestinal epithelial cells with enlarged nuclei and open chromatin distribution. X-rays show findings of malabsorption syndrome, cerebral atrophy which is reversible with zinc therapy and abnormal zinc absorption test using scintigraphy. Abnormal small bowel biopsy show the characteristic cell abnormalities that may be present without diarrhea or failure to thrive.
Precipitants
The symptoms usually develop after the neonatal period in exclusively breast-fed infants after weaning, due to a supposed zinc transport ligand in breast milk.
Provocation Tests
no
Diagnostic Procedures
In the laboratory there is low serum zinc. There is also low alkaline phosphatase levels because it is a zinc dependent enzyme. Serum zinc is especially low in infancy but may be normal in childhood or adolescence. There is low urinary zinc levels. Blood ammonia can be normal or mildly elevated. Biopsy of small bowel show loss of villous architecture and flattening of villi and cuboid intestinal epithelial cells with enlarged nuclei and open chromatin distribution. X-rays show findings of malabsorption syndrome, cerebral atrophy which is reversible with zinc therapy and abnormal zinc absorption test using scintigraphy. Abnormal small bowel biopsy show the characteristic cell abnormalities that may be present without diarrhea or failure to thrive.