Clinical presentation and proteomic signature of patients with TANGO2 mutations.

Transport And Golgi Organization protein 2 (TANGO2) deficiency has recently been identified as a rare metabolic disorder with a distinct clinical and biochemical phenotype of recurrent metabolic crises, hypoglycemia, lactic acidosis, rhabdomyolysis, arrhythmias, and encephalopathy with cognitive decline. We report nine subjects from seven independent families, and we studied muscle histology, respiratory chain enzyme activities in skeletal muscle and proteomic signature of fibroblasts. All nine subjects carried autosomal recessive TANGO2 mutations. Two carried the reported deletion of exons 3 to 9, one homozygous, one heterozygous with a 22q11.21 microdeletion inherited in trans. The other subjects carried three novel homozygous (c.262C>T/p.Arg88*; c.220A>C/p.Thr74Pro; c.380+1G>A), and two further novel heterozygous (c.6_9del/p.Phe6del); c.11-13delTCT/p.Phe5del mutations. Immunoblot analysis detected a significant decrease of TANGO2 protein. Muscle histology showed mild variation of fiber diameter, no ragged-red/cytochrome c oxidase-negative fibers and a defect of multiple respiratory chain enzymes and coenzyme Q10 (CoQ10 ) in two cases, suggesting a possible secondary defect of oxidative phosphorylation. Proteomic analysis in fibroblasts revealed significant changes in components of the mitochondrial fatty acid oxidation, plasma membrane, endoplasmic reticulum-Golgi network and secretory pathways. Clinical presentation of TANGO2 mutations is homogeneous and clinically recognizable. The hemizygous mutations in two patients suggest that some mutations leading to allele loss are difficult to detect. A combined defect of the respiratory chain enzymes and CoQ10 with altered levels of several membrane proteins provides molecular insights into the underlying pathophysiology and may guide rational new therapeutic interventions.

Successful pregnancy in maple syrup urine disease: a case report and review of the literature.

BACKGROUND: Maple syrup urine disease (MSUD) is an autosomal recessive disorder of branched-chain amino acid metabolism. Patients with MSUD are at risk of life-threatening metabolic decompensations with ketoacidosis and encephalopathy. These episodes are often triggered by physiological stress. Only few cases of pregnancies in MSUD mothers have been reported so far. CASE PRESENTATION: We present the favorable outcome of a pregnancy in a woman with classical MSUD. She presented in the metabolic outpatient clinic in week 7 of gestation. Branched-chain amino acid concentrations were measured at least weekly to adjust dietary leucine intake. Despite excellent compliance, leucine concentrations frequently exceeded the target value of < 300 µmol/L during the first trimester. From the second trimester until delivery, protein and leucine intake increased continuously to about threefold compared to pre-pregnancy values. To maximize patient safety during delivery and the postpartum period, a detailed plan including peripartal infusion therapy, dietary recommendations and monitoring parameters was developed. Primary Caesarean section was performed in week 38 of gestation, and the patient gave birth to a healthy girl. Lactation was successfully implemented. Leucine levels were maintained within the target range throughout the complete postpartum period. In addition to our case, we give an overview about all cases of pregnancies in MSUD mothers published so far. CONCLUSIONS: Management of pregnancy, delivery, postpartum period and lactation may be challenging in patients with MSUD. Careful monitoring and interdisciplinary collaboration is essential to minimize the risk of metabolic crisis, especially after delivery.

Mitochondrial fatty acid biosynthesis and muscle fiber plasticity in very long-chain acyl-CoA dehydrogenase-deficient mice.

The white skeletal muscle of very long-chain acyl-CoA-dehydrogenase-deficient (VLCAD-/- ) mice undergoes metabolic modification to compensate for defective ß-oxidation in a progressive and time-dependent manner by upregulating glucose oxidation. This metabolic regulation seems to be accompanied by morphologic adaptation of muscle fibers toward the glycolytic fiber type II with the concomitant upregulation of mitochondrial fatty acid biosynthesis (mFASII) and lipoic acid biosynthesis. Dietary supplementation of VLCAD-/- mice with different medium-chain triglycerides over 1 year revealed that odd-chain species has no effect on muscle fiber switch, whereas even-chain species inhibit progressive metabolic adaptation. Our study shows that muscle may undergo adaptive mechanisms that are modulated by dietary supplementation. We describe for the first time a concomitant change of mFASII in this muscular adaptation process.

Association of interleukin-13/-4 and toll-like receptor 10 with preterm births.

BACKGROUND: Preterm birth (PTB) is accompanied by an increased neonatal morbidity. The cause of PTB is multifactorial and the interplay between environmental and genetic factors - of mothers and newborns - determines the risk. OBJECTIVES: We were interested to identify fetal genes predisposing to PTB in the German population. METHODS: We started our study by screening 31 polymorphisms within 15 genes of 121 preterm infants born below 32 gestational weeks and 270 healthy controls. Genotyping was performed by restriction fragment length polymorphism. Statistical analyses used Armitage's trend test for single polymorphisms and FAMHAP for calculation of haplotypes. RESULTS: No single polymorphism showed association with PTB; however, haplotypes of interleukin (IL)-13/IL-4 and Toll-like receptor (TLR)-10 were associated (p = 0.0001 and p = 0.0011, respectively). The association was further confirmed in an extended population of a total of 164 preterm infants. Furthermore, one polymorphism in IL-13 showed a weak association with PTB in this population (p = 0.031). Finally, we analyzed whether the cause of PTB, i.e. medically indicated cesarean section versus spontaneous PTB, affects association results and found evidence in favor of a separate analysis of both groups. CONCLUSIONS: IL-13/IL-4 and TLR-10 might be involved in the genetics of PTB. The dissection of the genetic background may provide a deeper understanding of the pathophysiology of PTB and help to identify new drug targets for its prevention.