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Ng B.G.,Human Genetics Program Sanford Burnham Prebys Medical Discovery Institute La Jolla | Shiryaev S.A.,Human Genetics Program Sanford Burnham Prebys Medical Discovery Institute La Jolla | Rymen D.,Center for Human Genetics University of Leuven Leuven Belgium | Eklund E.A.,Lund University | And 50 more authors.
Human Mutation | Year: 2016

Congenital disorders of glycosylation (CDG) arise from pathogenic mutations in over 100 genes leading to impaired protein or lipid glycosylation. ALG1 encodes a β1,4 mannosyltransferase that catalyzes the addition of the first of nine mannose moieties to form a dolichol-lipid linked oligosaccharide intermediate required for proper N-linked glycosylation. ALG1 mutations cause a rare autosomal recessive disorder termed ALG1-CDG. To date 13 mutations in 18 patients from 14 families have been described with varying degrees of clinical severity. We identified and characterized 39 previously unreported cases of ALG1-CDG from 32 families and add 26 new mutations. Pathogenicity of each mutation was confirmed based on its inability to rescue impaired growth or hypoglycosylation of a standard biomarker in an alg1-deficient yeast strain. Using this approach we could not establish a rank order comparison of biomarker glycosylation and patient phenotype, but we identified mutations with a lethal outcome in the first two years of life. The recently identified protein-linked xeno-tetrasaccharide biomarker, NeuAc-Gal-GlcNAc2, was seen in all 27 patients tested. Our study triples the number of known patients and expands the molecular and clinical correlates of this disorder. © 2016 Wiley Periodicals, Inc.

PubMed | University of Hong Kong, Human Genome Research Institutes, Children's Hospital of Philadelphia, Greenwood Genetic Center Greenwood and College of Medicine and Health Sciences, University of Rwanda
Type: Journal Article | Journal: Molecular genetics & genomic medicine | Year: 2015

Limb body wall complex (LBWC) and amniotic band sequence (ABS) are multiple congenital anomaly conditions with craniofacial, limb, and ventral wall defects. LBWC and ABS are considered separate entities by some, and a continuum of severity of the same condition by others. The etiology of LBWC/ABS remains unknown and multiple hypotheses have been proposed. One individual with features of LBWC and his unaffected parents were whole exome sequenced and Sanger sequenced as confirmation of the mutation. Functional studies were conducted using morpholino knockdown studies followed by human mRNA rescue experiments. Using whole exome sequencing, a de novo heterozygous mutation was found in the gene IQCK: c.667C>G; p.Q223E and confirmed by Sanger sequencing in an individual with LBWC. Morpholino knockdown of iqck mRNA in the zebrafish showed ventral defects including failure of ventral fin to develop and cardiac edema. Human wild-type IQCK mRNA rescued the zebrafish phenotype, whereas human p.Q223E IQCK mRNA did not, but worsened the phenotype of the morpholino knockdown zebrafish. This study supports a genetic etiology for LBWC/ABS, or potentially a new syndrome.

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