The detection of echodense fetal bowel on ultrasound examination in the second trimester of pregnancy justifies invasive procedures such as amniocentesis to detect an underlying cause. We present a case in which initial tests identified only one mutation in the cystic fibrosis transmembrane regulator (CFTR)-gene of the fetus, the family history being negative for CF. Strongly reduced intestinal enzyme activities suggested intestinal obstruction and further increased the estimated risk for CF. After the 24th gestational week, a second mutation was found, confirming cystic fibrosis in this child. Problems in counseling in this particular case are discussed.

The pyruvate dehydrogenase complex (PDHc) is a multienzyme complex consisting of three catalytic and two regulatory enzymes, as well as a less well defined subunit called protein X. PDHc deficiency is a common cause of congenital lactic acidosis. Most patients with PDH deficiency have a mutation in the α chain of the PDH E1 enzyme. Very few patients have been described in whom the basic defect of a PDH deficiency is situated in the X protein. We studied a boy with severe lactic acidosis and developmental delay in whom a deficiency of PDH activity led to further investigations. Immunochemical analysis with anti-PDHc antibodies demonstrated an absence of the X component. This report is the fourth family in which an abnormal protein X has been found. In cases with PDH deficiency where no mutation of the PDHE1α gene is found, further investigations by means of immunoblotting with specific antibodies against the different subunits should be performed.

The very long chain fatty acids in cultured fibroblasts from six patients with the cerebro-hepato-renal syndrome of Zellweger, from six of their parents, from three controls, and also in three amniotic fluid control cell lines were analysed by gas chromatography. Increased concentrations of hexacosanoic acid (C26:O) were consistently found in the Zellweger syndrome. Also the ratios C26:O/C22:O, C25:O/C22:O, and C24:O/C22:O were elevated. The very long chain fatty acid levels and ratios in fibroblasts from the patients' parents were within the normal range. Findings in amniotic fluid cell lines indicate the possibility of antenatal diagnosis for Zellweger's syndrome. The similarities between neonatal adrenoleukodystrophy and Zellweger's syndrome suggest the applicability of this technique also in neonatal adrenoleukodystrophy.

Severe neurological symptoms, including intermittent ataxia, hallucinations and convulsions, associated with metabolic acidosis and branched-chain amino-acidemia occurred in a six-year-old girl with a variant form of maple syrup urine disease. The symptoms only appeared during periods of infection. Between these periods the girl was healthy and the biochemical findings were normal. In later episodes of infection the condition was successfully treated with a low protein diet and sodium bicarbonate. Analyses of 1-14C-leucine decarboxylase in fibroblasts revealed 10 per cent of normal activity in the girl and 50-70 per cent in the parents. The importance of early diagnosis of MSUD variants is discussed. This is the first published Swedish case of MSUD variant.