@article {134, title = {Expanding the Molecular and Clinical Phenotype of SSR4-CDG.}, journal = {Hum Mutat}, volume = {36}, year = {2015}, month = {2015 Nov}, pages = {1048-51}, abstract = {

Congenital disorders of glycosylation (CDG) are a group of mostly autosomal recessive disorders primarily characterized by neurological abnormalities. Recently, we described a single CDG patient with a de novo mutation in the X-linked gene, Signal Sequence Receptor 4 (SSR4). We performed whole-exome sequencing to identify causal variants in several affected individuals who had either an undifferentiated neurological disorder or unsolved CDG of unknown etiology based on abnormal transferrin glycosylation. We now report eight affected males with either de novo (4) or inherited (4) loss of function mutations in SSR4. Western blot analysis revealed that the mutations caused a complete loss of SSR4 protein. In nearly all cases, the abnormal glycosylation of serum transferrin was only slightly above the accepted normal cutoff range.

}, keywords = {Calcium-Binding Proteins, Congenital Disorders of Glycosylation, DNA Mutational Analysis, Exome, Gene Order, Genes, X-Linked, Genetic Loci, Humans, Male, Membrane Glycoproteins, Mutation, Phenotype, Receptors, Cytoplasmic and Nuclear, Receptors, Peptide}, issn = {1098-1004}, doi = {10.1002/humu.22856}, author = {Ng, Bobby G and Raymond, Kimiyo and Kircher, Martin and Buckingham, Kati J and Wood, Tim and Shendure, Jay and Nickerson, Deborah A and Bamshad, Michael J and Wong, Jonathan T S and Monteiro, Fabiola Paoli and Graham, Brett H and Jackson, Sheryl and Sparkes, Rebecca and Scheuerle, Angela E and Cathey, Sara and Kok, Fernando and Gibson, James B and Freeze, Hudson H} } @article {265, title = {Solving glycosylation disorders: fundamental approaches reveal complicated pathways.}, journal = {Am J Hum Genet}, volume = {94}, year = {2014}, month = {2014 Feb 06}, pages = {161-75}, abstract = {

Over 100 human genetic disorders result from mutations in glycosylation-related genes. In 2013, a new glycosylation disorder was reported every 17 days. This trend will probably continue given that at least 2\% of the human genome encodes glycan-biosynthesis and -recognition proteins. Established biosynthetic pathways provide many candidate genes, but finding unanticipated mutated genes will offer new insights into glycosylation. Simple glycobiomarkers can be used in narrowing the candidates identified by exome and genome sequencing, and those can be validated by glycosylation analysis of serum or cells from affected individuals. Model organisms will expand the understanding of these mutations{\textquoteright} impact on glycosylation and pathology. Here, we highlight some recently discovered glycosylation disorders and the barriers, breakthroughs, and surprises they presented. We predict that some glycosylation disorders might occur with greater frequency than current estimates of their prevalence. Moreover, the prevalence of some disorders differs substantially between European and African Americans.

}, keywords = {Congenital Disorders of Glycosylation, Exome, Genome, Human, Glucose, Glycogen, Glycosylation, Homeostasis, Humans, Mannose, Mutation}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2013.10.024}, author = {Freeze, Hudson H and Chong, Jessica X and Bamshad, Michael J and Ng, Bobby G} } @article {305, title = {Mosaicism of the UDP-galactose transporter SLC35A2 causes a congenital disorder of glycosylation.}, journal = {Am J Hum Genet}, volume = {92}, year = {2013}, month = {2013 Apr 04}, pages = {632-6}, abstract = {

Biochemical analysis and whole-exome sequencing identified mutations in the Golgi-localized UDP-galactose transporter SLC35A2 that define an undiagnosed X-linked congenital disorder of glycosylation (CDG) in three unrelated families. Each mutation reduced UDP-galactose transport, leading to galactose-deficient glycoproteins. Two affected males were somatic mosaics, suggesting that a wild-type SLC35A2 allele may be required for survival. In infancy, the commonly used biomarker transferrin showed abnormal glycosylation, but its appearance became normal later in childhood, without any corresponding clinical improvement. This may indicate selection against cells carrying the mutant allele. To detect other individuals with such mutations, we suggest transferrin testing in infancy. Here, we report somatic mosaicism in CDG, and our work stresses the importance of combining both genetic and biochemical diagnoses.

}, keywords = {Biological Transport, Case-Control Studies, Child, Child, Preschool, Congenital Disorders of Glycosylation, Exome, Female, Glycosylation, Humans, Male, Monosaccharide Transport Proteins, Mosaicism, Mutation, Spectrometry, Mass, Electrospray Ionization, Transferrin, Uridine Diphosphate Galactose}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2013.03.012}, author = {Ng, Bobby G and Buckingham, Kati J and Raymond, Kimiyo and Kircher, Martin and Turner, Emily H and He, Miao and Smith, Joshua D and Eroshkin, Alexey and Szybowska, Marta and Losfeld, Marie E and Chong, Jessica X and Kozenko, Mariya and Li, Chumei and Patterson, Marc C and Gilbert, Rodney D and Nickerson, Deborah A and Shendure, Jay and Bamshad, Michael J and Freeze, Hudson H} }