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1.  Mitochondrial involvement and erythronic acid as a novel biomarker in transaldolase deficiency 
Biochimica et biophysica acta  2010;1802(11):1028-1035.
Background
Sedoheptulose, arabitol, ribitol, and erythritol have been identified as key diagnostic metabolites in TALDO deficiency.
Method
Urine from 6 TALDO-deficient patients and TALDO-deficient knock-out mice were analyzed using 1H-NMR spectroscopy and GC–mass spectrometry.
Results
Our data confirm the known metabolic characteristics in TALDO-deficient patients. The β-furanose form was the major sedoheptulose anomer in TALDO-deficient patients. Erythronic acid was identified as a major abnormal metabolite in all patients and in knock-out TALDO mice implicating an as yet unknown biochemical pathway in this disease. A putative sequence of enzymatic reactions leading to the formation of erythronic acid is presented. The urinary concentration of the citric acid cycle intermediates 2-oxoglutaric acid and fumaric acid was increased in the majority of TALDO-deficient patients but not in the knock-out mice.
Conclusion
Erythronic acid is a novel and major hallmark in TALDO deficiency. The pathway leading to its production may play a role in healthy humans as well. In TALDO-deficient patients, there is an increased flux through this pathway. The finding of increased citric acid cycle intermediates hints toward a disturbed mitochondrial metabolism in TALDO deficiency.
doi:10.1016/j.bbadis.2010.06.007
PMCID: PMC3117462  PMID: 20600873
NMR spectroscopy; Citric acid cycle intermediates; Pentose phosphate pathway; Transaldolase deficiency; Polyols; Sedoheptulose; Erythronic acid; 2-Oxoglutaric acid
2.  SRD5A3 is required for the conversion of polyprenol to dolichol, essential for N-linked protein glycosylation 
Cell  2010;142(2):203-217.
SUMMARY
N-linked glycosylation is the most frequent modification of secreted and membrane-bound proteins in eukaryotic cells, disruption of which is the basis of the Congenital Disorders of Glycosylation (CDG). We describe a new type of CDG caused by mutations in the steroid 5α-reductase type 3 (SRD5A3) gene. Patients have mental retardation, ophthalmologic and cerebellar defects. We found that SRD5A3 is necessary for the reduction of the alpha-isoprene unit of polyprenols to form dolichols, required for synthesis of dolichol-linked monosaccharides and the oligosaccharide precursor used for N-glycosylation. The presence of residual dolichol in cells depleted for this enzyme suggests the existence of an unexpected alternative pathway for dolichol de novo biosynthesis. Our results thus suggest that SRD5A3 is likely to be the long-sought polyprenol reductase and reveal the genetic basis of one of the earliest steps in protein N-linked glycosylation.
doi:10.1016/j.cell.2010.06.001
PMCID: PMC2940322  PMID: 20637498
N-glycosylation; dolichol; polyprenol; SRD5A3
3.  Autosomal recessive cutis laxa syndrome revisited 
European Journal of Human Genetics  2009;17(9):1099-1110.
The clinical spectrum of the autosomal recessive cutis laxa syndromes is highly heterogeneous with respect to organ involvement and severity. One of the major diagnostic criteria is to detect abnormal elastin fibers. In several other clinically similar autosomal recessive syndromes, however, the classic histological anomalies are absent, and the definite diagnosis remains uncertain. In cutis laxa patients mutations have been demonstrated in elastin or fibulin genes, but in the majority of patients the underlying genetic etiology remains unknown. Recently, we found mutations in the ATP6V0A2 gene in families with autosomal recessive cutis laxa. This genetic defect is associated with abnormal glycosylation leading to a distinct combined disorder of the biosynthesis of N- and O-linked glycans. Interestingly, similar mutations have been found in patients with wrinkly skin syndrome, without the presence of severe skin symptoms of elastin deficiency. These findings suggest that the cutis laxa and wrinkly skin syndromes are phenotypic variants of the same disorder. Interestingly many phenotypically similar patients carry no mutations in the ATP6V0A2 gene. The variable presence of protein glycosylation abnormalities in the diverse clinical forms of the wrinkled skin-cutis laxa syndrome spectrum necessitates revisiting the diagnostic criteria to be able to offer adequate prognosis assessment and counseling. This paper aims at describing the spectrum of clinical features of the various forms of autosomal recessive cutis laxa syndromes. Based on the recently unraveled novel genetic entity we also review the genetic aspects in cutis laxa syndromes including genotype–phenotype correlations and suggest a practical diagnostic approach.
doi:10.1038/ejhg.2009.22
PMCID: PMC2986595  PMID: 19401719
cutis laxa; wrinkled skin; congenital disorders of glycosylation; gerodermia osteodysplastica; De Barsy Syndrome; ATP6V0A2

Results 1-3 (3)