Polymerase gamma deficiency (POLG): clinical course in a child with a two stage evolution from infantile myocerebrohepatopathy spectrum to an Alpers syndrome and neuropathological findings of Leigh's encephalopathy.

AIMS: Description of the clinical course in a child compound heterozygous for POLG1 mutations, neuropathology findings and results of dietary treatment based on fasting avoidance and long chain triglycerides (LCT) restriction. RESULTS: At 3(1/2) months of age the patient presented with severe hypoglycemia, hyperlactatemia, moderate ketosis and hepatic failure. Fasting hypoglycemia occurred 8 h after meals. The hypoglycemia did not respond to glucagon. She was supplemented with IV glucose and/or frequent feedings, but developed liver insufficiency which was reversed by long-chain triglyceride (LCT) restriction. Alpha-foeto-protein (AFP) levels were elevated and returned to low values after dietary treatment. Liver biopsy displayed cirrhosis, bile ductular proliferation, steatosis, isolated complex IV defect in part of the liver mitochondria, and mitochondrial DNA depletion (27% of control values). Two heterozygous mutations (p. [Ala467Thr] + p. [Gly848Ser]) were found in the POLG1 gene. At 3 years of age she progressively developed refractory mixed type seizures including a focal component and psychomotor regression which fulfilled the criteria of Alpers syndrome (AS) although the initial presentation was compatible with infantile myocerebrohepatopathy spectrum (MCHS). She died at 5 years of age of respiratory insufficiency. Neuropathologic investigation revealed lesions in the right striatal area and the inferior colliculi typical for Leigh's encephalopathy. CONCLUSION: The present patient showed an evolution from infantile MCHS to AS, and dietary treatment seemed to slow the progression of liver failure. In spite of the late clinical features of AS, it extends the neuropathological spectrum of AS and polymerase gamma deficiency (POLG) to Leigh syndrome lesions.

High phenylalanine levels directly affect mood and sustained attention in adults with phenylketonuria: a randomised, double-blind, placebo-controlled, crossover trial.

The main debate in the treatment of Phenylketonuria (PKU) is whether adult patients need the strict phenylalanine (Phe)-restricted diet. Physicians and patients lack evidence-based guidelines to help them make well-informed choices. We have carried out the first randomised double-blind placebo-controlled trial into the effects of short-term elevation of Phe levels on neuropsychological functions and mood of adults with PKU. Nine continuously treated adults with PKU underwent two 4-week supplementation periods: one with Phe, mimicking normal dietary intake, and one with placebo in randomly allocated order via a randomisation coding list in a double-blind cross-over design. A set of neuropsychological tests (Amsterdam Neuropsychological Tasks) was administered at the end of each study period. In addition, patients and for each patient a friend or relative, completed weekly Profile of Mood States (POMS) questionnaires, evaluating the patients' mood. Phe levels were measured twice weekly. Mean plasma Phe levels were significantly higher during Phe supplementation compared with placebo (p = 0.008). Neuropsychological tests demonstrated an impairment in sustained attention during Phe supplementation (p = 0.029). Both patients and their friend or relative reported lower scores on the POMS questionnaires during Phe supplementation (p = 0.017 and p = 0.040, respectively). High plasma Phe levels have a direct negative effect on both sustained attention and on mood in adult patients with PKU. A Phe-restricted "diet for life" might be an advisable option for many.

Biochemical abnormalities in a patient with thymidine phosphorylase deficiency with fatal outcome.

Deficiency of the cytosolic enzyme thymidine phosphorylase (TP) causes a multisystem disorder called mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) syndrome. Clinical symptoms are gastrointestinal dysfunction, muscle involvement and neurological deterioration. TP deficiency is biochemically characterised by accumulation of thymidine and deoxyuridine in body fluids and compromised mitochondrial deoxyribose nucleic acid (mtDNA) integrity (depletion and multiple deletions). In this report we describe a patient with the clinical and biochemical features related to the end stage of the disease. Home parenteral nutrition had started to improve the clinical condition and preparations were initiated for stem cell transplantation (SCT) as a last resort treatment. Unfortunately, the patient died during the induction phase of SCT. This report shows that TP deficiency is a severe clinical condition with a broad spectrum of affected tissues. TP deficiency can be easily determined by the measurement of pyrimidine metabolites in body fluids and TP activity in peripheral blood leucocytes. Early detection and treatment may prevent the progress of the clinical symptoms and, therefore, should be considered for inclusion in newborn screening programmes.

Mitochondrial mosaics in the liver of 3 infants with mtDNA defects.

BACKGROUND: In muscle cytochrome oxidase (COX) negative fibers (mitochondrial mosaics) have often been visualized. METHODS: COX activity staining of liver for light and electron microscopy, muscle stains, blue native gel electrophoresis and activity assays of respiratory chain proteins, their immunolocalisation, mitochondrial and nuclear DNA analysis. RESULTS: Three unrelated infants showed a mitochondrial mosaic in the liver after staining for COX activity, i.e. hepatocytes with strongly reactive mitochondria were found adjacent to cells with many negative, or barely reactive, mitochondria. Deficiency was most severe in the patient diagnosed with Pearson syndrome. Ragged-red fibers were absent in muscle biopsies of all patients. Enzyme biochemistry was not diagnostic in muscle, fibroblasts and lymphocytes. Blue native gel electrophoresis of liver tissue, but not of muscle, demonstrated a decreased activity of complex IV; in both muscle and liver subcomplexes of complex V were seen. Immunocytochemistry of complex IV confirmed the mosaic pattern in two livers, but not in fibroblasts. MRI of the brain revealed severe white matter cavitation in the Pearson case, but only slight cortical atrophy in the Alpers-Huttenlocher patient, and a normal image in the 3rd. MtDNA in leucocytes showed a common deletion in 50% of the mtDNA molecules of the Pearson patient. In the patient diagnosed with Alpers-Huttenlocher syndrome, mtDNA was depleted for 60% in muscle. In the 3rd patient muscular and hepatic mtDNA was depleted for more than 70%. Mutations in the nuclear encoded gene of POLG were subsequently found in both the 2nd and 3rd patients. CONCLUSION: Histoenzymatic COX staining of a liver biopsy is fast and yields crucial data about the pathogenesis; it indicates whether mtDNA should be assayed. Each time a mitochondrial disorder is suspected and muscle data are non-diagnostic, a liver biopsy should be recommended. Mosaics are probably more frequent than observed until now. A novel pathogenic mutation in POLG is reported.Tentative explanations for the mitochondrial mosaics are, in one patient, unequal partition of mutated mitochondria during mitoses, and in two others, an interaction between products of several genes required for mtDNA maintenance.