On the nomenclature of congenital disorders of ... - Euroglycanet

54 downloads 0 Views 195KB Size Report
On the nomenclature of congenital disorders of glycosylation (CDG). J. Jaeken & T. Hennet & H. H. Freeze & G. Matthijs. Received: 25 June 2008 /Submitted in ...
J Inherit Metab Dis DOI 10.1007/s10545-008-0983-x

RAPID COMMUNICATION

On the nomenclature of congenital disorders of glycosylation (CDG) J. Jaeken & T. Hennet & H. H. Freeze & G. Matthijs

Received: 25 June 2008 / Submitted in revised form: 12 August 2008 / Accepted: 22 August 2008 / Published online: 24 October 2008 # SSIEM and Springer 2008

Summary A new nomenclature of CDG is proposed because the current one is too complex for clinicians and provides no added value. Abbreviation CDG congenital disorders of glycosylation

It is now more than 10 years since one of us (J.J.) introduced a classification for CDG (CDG Ia etc., CDG IIa etc.) essentially on the basis of the serum

Communicating editor: Verena Peters Competing interests: None declared J. Jaeken Center for Metabolic Disease, Katholieke Universiteit Leuven, Leuven, Belgium T. Hennet Department of Physiology, University of Zu¨rich, Zu¨rich, Switzerland H. H. Freeze Burnham Institute for Medical Research, La Jolla, California, USA G. Matthijs Center for Human Genetics, Katholieke Universiteit Leuven, Leuven, Belgium J. Jaeken (*) Universitaire Ziekenhuis Gasthuisberg, Herestraat 49, Leuven, B-3000, Belgium e-mail: [email protected]

transferrin pattern obtained by isoelectrofocusing (Jaeken et al 1994). A nomenclature system that essentially (sub)classified the different types of CDG alphabetically was proposed by the participants of the First International workshop on CDG and related disorders, in Leuven in 1999, and widely announced (Aebi et al 1999; Matthijs 2000; Participants 2000). We think that time has come to reconsider this matter. More specifically, it is our strong feeling that the current classification should be discontinued for a number of reasons. 1. The number of CDG has increased tremendously. In the 28 years that have elapsed since the first description of patients, some 40 types of CDG (including protein and lipid glycosylation defects) have been discovered (Jaeken and Matthijs 2007; Freeze 2007). There is every reason to believe that this will continue for many years, since at least 200 genes seem to be involved in glycosylation! This large number of CDG makes the classification extremely complex, particularly for the metabolic and other clinicians who have to use it in their daily practice. Moreover, since this classification is alphabetically and chronologically by the order of discovery, it provides no added value since it does not refer to real biological features such as enzymes or genes. Thus, it only complicates the recognition and recall of the basic defect. 2. That there is no need for this classification is well illustrated by the CDG due to an O-glycosylation defect. These are not included in this classification and have Fpopular_ names and/or Fbiochemical_

J Inherit Metab Dis

names that are informative about the nature of the disease (e.g. muscle-eye-brain disease or POMT defect, hereditary multiple exostoses, familial tumoral calcinosis...). 3. Even if it were decided to continue this classification, it would be extremely difficult to imagine how to proceed further in this way. It would bring us into insurmountable difficulties. How do we classify the upcoming disorders of dolichol biosynthesis (Kranz et al 2007), the lipid glycosylation disorders (Simpson et al 2004) and so on? Our suggestion is to keep (of course) Congenital Disorders of Glycosylation (CDG) as an umbrella name for all protein glycosylation disorders and to extend it to the lipid glycosylation disorders. To indicate the specific disorder, we propose to make

obligatory the use of the gene name. But in parallel, the name of the protein (enzyme, transporter, chaperone, ...) may be used (abbreviated or not; this may be a Ftrivial_ name: e.g. CDG due to mannosyltransferase VIII deficiency instead of dolichol-P-Man:Man7GlcNAc2-PP-dolichol mannosyltransferase deficiency). In a transition period the Fold_ nomenclature can be included in brackets as that nomenclature is gradually replaced (see the Tables 1–4). One is free to add the abbreviated designation CDG in brackets after the gene name: e.g. PMM2 deficiency (CDG). As long as the primary (genetic) defect is unknown for a specific type, we will continue to call the disease CDG-x; hence, this group constitutes a series of cases and patients Fto be solved_. We look forward to receiving comments on this proposal.

Proposed nomenclature for CDG (nomenclature to be superseded is included in italics within brackets)

Table 1 Defects in protein N-glycosylation Defective gene

Defective protein

OMIM

PMM2 (CDG-Ia) MPI (CDG-Ib) ALG6 (CDG-Ic) NOT56L (CDG-Id) ALG 12 (CDG-Ig) ALG 8 (CDG-Ih) ALG2 (CDG-Ii) DPAGT1 (CDG-Ij) HMT1 (CDG-Ik) DIBD1 (CDG-Il)

Phosphomannomutase 2 Phosphomannose isomerase Dol-P-Glc:Man9-GlcNAc2-P-P-Dol glucosyltransferase (glucosyltransferase 1) Dol-P-Man:Man5-GlcNAc2-P-P-Dol mannosyltransferase (mannosyltransferase 6) Dol-P-Man:Man7-GlcNAc2-P-P-Dol mannosyltransferase (mannosyltransferase 8) Dol-P-Glc:Glc1-Man9-GlcNAc2-P-P-Dol glucosyltransferase (glucosyltransferase 2) GDP-Man:Man1-GlcNAc2-P-P-Dol mannosyltransferase (mannosyltransferase 2) UDP-GlcNAc:Dol-P-GlcNAc-P transferase GDP-Man:GlcNAc2-P-P-Dol mannosyltransferase (mannosyltransferase 1) Dol-P-Man:Man6-and Man8-GlcNA2-P-P-Dol mannosyltransferase (mannosyltransferase 7-9) Flippase of Man5GlcNAc2-PP-Dol N-acetylglucosaminyltransferase 2 Glucosidase 1 Oligosaccharyltransferase subunit

601785 602579 603147 601110 607143 608104 607906 608093 608540 608776

RFT1 (CDG-In) MGAT2 (CDG-IIa) GLS1 (CDG-IIb) TUSC3

611633 602616 606056 601385

J Inherit Metab Dis Table 2 Defects in protein O-glycosylation Defective gene

Defective protein

OMIM

*O-xylosylglycan synthesis EXT1/EXT2 (multiple cartilaginous exotoses)

Glucuronyltransferase/N-acetylglucosaminyltransferase b-1,4-galactosyltransferase 7

608177/ 608210 604327

Polypeptide N-acetylgalactosaminyltransferase 3

601756

Solute carrier family 35 (UDP-glucuronic acid/ UDP-N-acetylgalactosamine dual transporter), member D1

610804

Protein-O-mannosyltransferase 1/proteinO-mannosyltransferase 2 Protein-O-mannose b-1,2-N-acetylglucosaminyltransferase Fukutin Fukutin-related protein N-Acetylglucosaminyltransferase-like protein

607423 606822 607440 606596 603590

O-Fucose-specific b-1,3-N-acetylglucosaminyltransferase O-Fucose-specific b-1,3-glucosyltransferase

602576 610308

B4GALT7 *O-N-acetylgalactosaminylglycan synthesis GALNT3 (familial tumoral calcinosis) *O-xylosyl/N-acetylgalactosaminylglycan synthesis SLC35D1 (Schneckenbecken dysplasia)

*O-mannosylglycan synthesis POMT1/POMT2 (cong. muscular dystrophy spectrum) POMGNT1 (cong. muscular dystrophy spectrum) FKTN (cong. muscular dystrophy spectrum) FKRP (cong. muscular dystrophy spectrum) LARGE (cong. muscular dystrophy spectrum) *O-fucosylglycan synthesis SCDO3 (spondylocostal dysostosis type 3) B3GALTL (Peters plus syndrome)

Table 3 Defects in glycosphingolipid and glycosylphosphatidylinositol anchor glycosylation Defective gene

Defective protein

OMIM

SIAT9 (Amish infantile epilepsy) PIGM (glycosylphosphatidylinositol deficiency)

Lactosylceramide a-2,3 sialyltransferase (GM3 synthase) Phosphatidylinositolglycan, class M

609056 610273

Table 4 Defects in multiple glycosylation and other pathways Defective gene

Defective protein

OMIM

DPM1 (CDG-Ie)

GDP-Man:Dol-P-mannosyltransferase (Dol-P-Man synthase 1) Lec35 (Man-P-Dol utilization 1) b-1,4-galactosyltransferase 1 UDP-GlcNAc epimerase/kinase CMP-sialic acid transporter

603503

GDP-fucose transporter

605881

Dolichol kinase

610768

Component of conserved oligomeric Golgi complex 7 Component of conserved oligomeric Golgi complex 1 Component of conserved oligomeric Golgi complex 8

606978 606973 606979

V0 subunit A2 of vesicular H(+)-ATPase

611716

MPDU1 (CDG-If) B4GALT1 (CDG-IId) GNE (hereditary inclusion body myopathy) SLC35A1 (CDG-IIf) (CMP-sialic acid transporter deficiency) SLC35C1 (CDG-IIc) (GDP-fucose transporter deficiency) *Dolichol pathway DK1 (CDG-Im) *COGa complex COG7 defect (CDG-IIe) COG1 defect (CDG-IIg) COG8 defect *V-ATPase ATP6VOA2 defect (cutis laxa type II) a

Conserved oligomeric Golgi

608799 607091 600737 605634

J Inherit Metab Dis

References Jaeken J, Schachter H, Carchon H, De Cock P, Coddeville B, Spik G (1994) Carbohydrate deficient glycoprotein syndrome type II: a deficiency in Golgi localised Nacetylglucosaminyltransferase II. Arch Dis Child 71: 123–127. Aebi M, Helenius A, Schenk B, et al (1999) Carbohydratedeficient glycoprotein syndromes become congenital disorders of glycosylation: an updated nomenclature for CDG. First International Workshop on CDGS. Glycoconj J 16: 669–671. Participants (2000) First International Workshop on CDGS. Carbohydrate-deficient glycoprotein syndromes become congenital disorders of glycosylation: an updated nomenclature for CDG. Glycobiology 10: iii–vi.

Matthijs G (2000) Congenital disorders of glycosylation. Trends Biochem Sci 25: 428. doi:10.1016/S0968-0004(00)01629-7. Freeze HH (2007) Congenital disorders of glycosylation: CDG-I, CDG-II, and beyond. Curr Mol Med 7: 389–396. doi:10. 2174/156652407780831548. Jaeken J, Matthijs G (2007) Congenital disorders of glycosylation. A rapidly expanding disease family. Annu Rev Genomics Hum Genet 8: 261–278. doi:10.1146/annurev. genom.8.080706.092327. Kranz C, Jungeblut C, Denecke J, et al (2007) A defect in dolichol phosphate biosynthesis causes a new inherited disorder with death in early infancy. Am J Hum Genet 80: 433–440. doi:10.1086/512130. Simpson MA, Cross H, Proukakis C, et al (2004) Infantile-onset symptomatic epilepsy syndrome caused by a homozygous loss-of-function mutation of GM3 synthase. Nat Genet 36: 1225–1229. doi:10.1038/ng1460.