Congenital intestinal diarrhoeal diseases: A diagnostic and therapeutic challenge.

Congenital diarrhoeal disorders are a heterogeneous group of inherited malabsorptive or secretory diseases typically appearing in the first weeks of life, which may be triggered by the introduction of distinct nutrients. However, they may also be unrecognised for a while and triggered by exogenous factors later on. In principle, they can be clinically classified as osmotic, secretory or inflammatory diarrhoea. In recent years the disease-causing molecular defects of these congenital disorders have been identified. According to the underlying pathophysiology they can be classified into four main groups: 1) Defects of digestion, absorption and transport of nutrients or electrolytes 2) Defects of absorptive enterocyte differentiation or polarisation 3) Defects of the enteroendocrine cells 4) Defects of the immune system affecting the intestine. Here, we describe the clinical presentation of congenital intestinal diarrhoeal diseases, the diagnostic work-up and specific treatment aspects.