NovelGNE mutations in Italian families with autosomal recessive hereditary inclusion-body myopathy

Department of Neuroscience, Catholic University, Rome, Italy.
Human Mutation (Impact Factor: 5.14). 06/2004; 23(6):632. DOI: 10.1002/humu.9252
Source: PubMed


The most common form of autosomal recessive (AR) hereditary inclusion-body myopathy (HIBM), originally described in Persian-Jewish families, is characterized by onset in early adult life with weakness and atrophy of distal lower limb muscles, which progress proximally and relatively spare the quadriceps. AR HIBM is associated with mutations in the UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase gene (GNE) on chromosome 9p12-13. In the present study we have identified seven novel GNE mutations in patients from five unrelated Italian families with clinical and pathologic features indicative of AR HIBM. Four were missense mutations (c.1556A>G [p.N519S], c.79C>T [p.P27S], c.1798G>A [p.A600T] and c.616G>A [p.G206S]), two consisted in a single-base deletion (c.616delG [p.G206fsX4] and c.1130delT [p.I377fsX16]) and one in an intronic single-base insertion (c.1070+2dupT). These latter findings further extend the type of GNE mutations associated with HIBM. Furthermore, in one patient we also identified the c.737G>A [p.R246Q] missense mutation that corresponds to the one previously reported in a family from the Bahamas. Interestingly, in two of our families distinct mutations affected nucleotide c.616 in exon 3 (c.616delG and c.616G>A). The possibility of specific portions of the gene being more prone to mutations remains to be elucidated.

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Available from: Massimiliano Mirabella, Sep 29, 2014
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    • "Approximately 80 different mutations in GNE have been previously reported [18,33,39-42], of which only two are in splice sites. Like the c.1816+5G>A mutation described herein, these mutations likely result in null alleles [10,43]. The vast majority of mutations in GNE are missense [33], and no patients have been recorded as homozygous or compound heterozygous for two null mutations, suggesting a complete loss of function of GNE might be lethal in humans [5], as in mice [44]. "
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    ABSTRACT: Many myopathies share clinical features in common, and diagnosis often requires genetic testing. We ascertained a family in which five siblings presented with distal muscle weakness of unknown etiology. We performed high-density genomewide linkage analysis and mutation screening of candidate genes to identify the genetic defect in the family. Preserved clinical biopsy material was reviewed to confirm the diagnosis, and reverse transcriptase PCR was used to determine the molecular effect of a splice site mutation. The linkage scan excluded the majority of known myopathy genes, but one linkage peak included the gene GNE, in which mutations cause autosomal recessive hereditary inclusion body myopathy type 2 (HIBM2). Muscle biopsy tissue from a patient showed myopathic features, including small basophilic fibers with vacuoles. Sequence analysis of GNE revealed affected individuals were compound heterozygous for a novel mutation in the 5' splice donor site of intron 10 (c.1816+5G>A) and a previously reported missense mutation (c.2086G>A, p.V696M), confirming the diagnosis as HIBM2. The splice site mutation correlated with exclusion of exon 10 from the transcript, which is predicted to produce an in-frame deletion (p.G545_D605del) of 61 amino acids in the kinase domain of the GNE protein. The father of the proband was heterozygous for the splice site mutation and exhibited mild distal weakness late in life. Our study expands on the extensive allelic heterogeneity of HIBM2 and demonstrates the value of linkage analysis in resolving ambiguous clinical findings to achieve a molecular diagnosis.
    Full-text · Article · Jun 2011 · BMC Medical Genetics
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    • "Amino acid substitution GNE exon Structural position (domain b , secondary structure, function) References 45 p.N519S 9 Kinase, α4; vicinity of the glucose and magnesium binding sites; Ser is present in structurally equivalent position of the Mlc protein, which does not bind glucose (Figure 1B); helix–helix contacts rearranged in Mlc; changes in the predicted secondary structure by CD spectroscopy (Penner et al. 2006) Broccolini et al. 2004 46 p.A524V 9 Kinase, α4; interface between α4 (glucose and magnesium binding helix) and α11; Ala is conserved among structurally similar proteins except HKI carrying Thr Behin et al. 2008 Darvish et al. 2002 Liewluck et al. 2006 47 p.F528C 9 Kinase, α4; interface between α4 (glucose and magnesium binding helix) and α11 Eisenberg et al. 2003 48 p.I557T 10 Kinase, β8; part of a ROK motif 1 Eisenberg et al. 2003 Tomimitsu et al. 2004 49 p.G559R 10 Kinase, β8α5; part of a ROK motif 1 Huizing et al. 2004 50 p.V572L 10 Kinase, α5α6; connection region between ROK motifs 1 and 2; vicinity of zinc and glucose binding; may be part of dimerization interface (Penner et al. 2006) Kayashima et al. 2002 Kim et al. 2006 Tomimitsu et al. 2002 51 p.G576E 10 Kinase, α5α6; vicinity of a zinc and substrate binding site (ROK motif 2); structural changes affect the dimerization interface due to introduction of a glutamyl side chain, resulting in trimer formation (instead of hexamer) (Penner et al. 2006) Eisenberg et al. 2001 52 p.I587T 10 Kinase, α6; vicinity of a zinc and substrate binding site (ROK motif 2) Behin et al. 2008 Eisenberg et al. 2003 53 p.A591T 10 Kinase, α6; interface with α6 Kim et al. 2006 54 p.A600T 10 Kinase, α6 ; interfaces with α7, α8, α9 Broccolini et al. 2004 55 p.A630T 11 Kinase, α7; vicinity of ADP binding; interface with α6 Nishino et al. 2002 56 p.A631T 11 Kinase, α7; vicinity of ADP binding; interface with α6 Behin et al. 2008 Eisenberg et al. 2001 57 p.A631V 11 Kinase, α7; vicinity of ADP binding; interface with α6 Nishino et al. 2002 Eisenberg et al. 2003 Tomimitsu et al. 2002 Vasconcelos et al. "
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    ABSTRACT: The bifunctional enzyme UDP-GlcNAc 2-epimerase/ ManNAc kinase (GNE/MNK), encoded by the GNE gene, catalyzes the first two committed, rate-limiting steps in the biosynthesis of N-acetylneuraminic acid (sialic acid). GNE/MNK is feedback inhibited by binding of the downstream product, CMP-sialic acid in its allosteric site. GNE mutations can result in two human disorders, hereditary inclusion body myopathy (HIBM) or sialuria. So far, no active site geometry predictions or conformational transitions involved with function are available for mammalian GNE/MNK. The N-terminal GNE domain is homologous to various prokaryotic 2-epimerases, some of which have solved crystallographic structures. The C-terminal MNK domain belongs to the sugar kinases superfamily; its crystallographic structure is solved at 2.84 A and three-dimensional structures have also been reported for several other kinases. In this work, we employed available structural data of GNE/MNK homologs to model the active sites of human GNE/MNK and identify critical amino acid residues responsible for interactions with substrates. In addition, we modeled effects of GNE/MNK missense mutations associated with HIBM or sialuria on helix arrangement, substrate binding, and enzyme action. We found that all reported mutations are associated with the active sites or secondary structure interfaces of GNE/MNK. The Persian-Jewish HIBM founder mutation p.M712T is located at the interface alpha4alpha10 and likely affects GlcNAc, Mg2+, and ATP binding. This work contributes to further understanding of GNE/MNK function and ligand binding, which may assist future studies for therapeutic options that target misfolded GNE/MNK in HIBM and/or sialuria.
    Preview · Article · Nov 2009 · Glycobiology
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    • ", p. R246W or p.R246Q [19,22,28–30], p.303V or p.303X [19] [25], p.P511H or p.P511L [10] [31], and p.A631T and p.A631V [5] [19] [21] [25] [32]. Also some specific GNE mutations arose presumably independently in multiple ethnicities: p.R246Q in Italy, Bahamas and Taiwan [19] [28] [29], p.D378Y in Japan and Ireland [5] [21], p.A524V in Thailand, Mexico and France [10] [22] [32], p.I557T in Italy and Japan [21] [24], p. A631V in Germany, Ireland and Japan [5] [21] [25], and p.V696M in Thailand, India and Algeria [10] [19] [32] [33]. Fig. 1 "
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    ABSTRACT: Hereditary Inclusion Body Myopathy (HIBM) is an autosomal recessive, quadriceps sparing type commonly referred to as HIBM but also termed h-IBM or Inclusion Body Myopathy 2 (IBM2). The clinical manifestations begin with muscle weakness progressing over the next 10–20 years uniquely sparing the quadriceps until the most advanced stage of the disease. Histopathology of an HIBM muscle biopsy shows rimmed vacuoles on Gomori's trichrome stain, small fibers in groups and tubulofilaments without evidence of inflammation. In affected individuals distinct mutations have been identified in the GNE gene, which encodes the bifunctional enzyme uridine diphospho-N-acetylglucosamine (UDP-GlcNAc) 2-epimerase/N-acetyl-mannosamine (ManNAc) kinase (GNE/MNK). GNE/MNK catalyzes the first two committed steps in the biosynthesis of acetylneuraminic acid (Neu5Ac), an abundant and functionally important sugar. The generation of HIBM animal models has led to novel insights into both the disease and the role of GNE/MNK in pathophysiology. Recent advances in therapeutic approaches for HIBM, including administration of N-acetyl-mannosamine (ManNAc), a precursor of Neu5Ac will be discussed.
    Preview · Article · Sep 2009 · Biochimica et Biophysica Acta
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