Iron-overload disease in infants involving fetal growth retardation, lactic acidosis, liver haemosiderosis, and aminoaciduria.

BACKGROUND: Several cases of a distinctive lethal neonatal disorder have been found in the Children's Hospital, Helsinki, Finland. However, the combination of presenting features is not typical of any known metabolic disease. We have analysed all known cases of this disorder in the hospital since 1965 and in Finland since 1990 to define clinical features of the disease.

METHODS: We studied 17 newborn infants with severe growth retardation from 12 Finnish families and traced their genealogy. In addition to routine clinical studies, diagnostic workup included analysis of respiratory-chain function in isolated muscle mitochondria and necropsy specimens, pyruvate dehydrogenase complex activities in fibroblasts, analysis of aminoacids and organic acids in urine, staining of tissue samples for iron, and assay of liver iron content.

FINDINGS: The infants were born near term (mean 37.8 [SD 3] gestational weeks) but were severely growth retarded (birthweight 1690 [460] g--ie, -3.8 [SD 0.6] SD score for gestational age). By age 24 h, mean pH was 7.00 (0.12), lactate 12.2 (7.5) mmol/L, and pyruvate 121 (57) micromol/L. All had aminoaciduria and failed to thrive; nine died neonatally (age 2-12 days), and eight died in infancy (1-4 months). The liver of four infants showed microscopic haemosiderosis and increased iron content (2.8-5.5 mg iron/g dry weight). In those four infants serum ferritin concentration (1260-2700 microg/L) and transferrin saturation (61-100%) were high, transferrin concentration (0.54-0.76 g/L) was low.

INTERPRETATION: We describe a previously unrecognised clinical picture of a genetic disease, which presents with fetal growth retardation and lactic acidosis after birth. Genealogical studies indicate an autosomal-recessive mode of inheritance for this disease, which is distinct from other lactic acidoses, neonatal haemochromatosis, and hepatitis. The diagnostic criteria are: fetal growth retardation; severe lactic acidosis; aminoaciduria; iron overload with haemosiderosis of the liver, increased serum ferritin concentration, hypotransferrinaemia, and increased transferrin iron saturation. Organ dysfunction may be partly due to the toxic effects of free iron.