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The discovery of a fructose-1,6-diphosphatase deficiency in two sisters leads to the discussion of the various loading tests which are required for the diagnosis. The diagnosis may be discussed clinically with type I glycogenosis, and biologically with hereditary fructose intolerance. The specific characteristics of these disorders are analyzed as well as the problem of fructose induced hypoglucosemia. The failure of the treatment with folic acid in one of the cases leads to emphasize the suppression of prolonged fast in order to avoid acute accidents.

Hematologic, genetic and biochemical data of two patients suffering from glucosephosphate isomerase deficiency are described. In one of them a generalized deficiency could be demonstrated. The molecular instability of the deficient enzyme results in early inactivation. Its consequences for carbohydrate metabolism are exposed. Besides a non-spherocytic hemolytic anemia, a hepatic glycogenosis could be observed. Our patients are compared to litterature.

Famialial defect of hepatic fructose-1,6-diphosphatase. Diagnosis was suspected in a male newborn since a brother was also concerned by the disease. The disease may be therefore diagnosed early, when the onset is neonatal. In the neonatal distress syndromes due to hereditery disorders of metabolism, a semiologic field may be isolated in which symptoms begin after an interval of short duration with hypoglycemia, hepatomegaly, lactic acidosis and ketosis ("enlarged liver hypoglycemia"). This possibility leads first to a symptomatic treatment of hypoglycemia and acidoketosis, then to the feeding with human milk and simple functional tests for the diagnostic approach.

Mannosidosis is a new and rare disorder. The following clinical symptoms should evolve its diagnosis: facial dysmorphy with slight mental retardation; bone deformities with abnormal L2 vertebra and craniosynostosis; biological abnormalities with vacuolized lymphocytes and absence of urinary mucopolysaccharides. Definite diagnosis relies upon detection of mannose oligosaccharides in the urine and serum deficiency of alpha-D-mannosidase.

Four cases of hereditary fructose intolerance with an early onset are reported. The features of acute liver failure in the neonatal period include a haemorrhagic syndrome, collapse, neurological features, hypoglycaemia, disturbed bleeding and clotting studies and abnormal liver function tests. Investigations into the aetiology include a search for bacterial or viral infection but particularly for a metabolic cause: especially for hereditary fructose intolerance which may be difficult to distinguish from tyrosinosis. Finally, methods of treatment are discussed: continuous glucose infusion, exchange transfusion, assisted ventilation, and dietary measures beginning with protein exclusion. The importance of careful observation is stressed (particularly sequential studies of bloodclotting factors).