Monogenic Diabetes
Gene: CEL
Comment on list classification: Remains technically challenging but most of critical region (First 5 repeats of exon 11 VNTR) are callable on short read data.Created: 6 Jan 2026, 10:56 a.m. | Last Modified: 6 Jan 2026, 10:56 a.m.
Panel Version: 0.155
Comment on mode of pathogenicity: Dominant Negative Gain-of-Function experimentally establishedCreated: 6 Jan 2026, 10:54 a.m. | Last Modified: 6 Jan 2026, 10:54 a.m.
Panel Version: 1.29
Specific CEL gene variants have been associated with MODY8, and potentially hereditary chronic pancreatitis, in 5 families to date (PMID:37726640). All families have single base frame shift deletions in the VNTR (Variable Number of Tandem Repeats) region of the last exon (exon 11) of the CEL gene, specifically in the first (DEL1), fourth and fifth (DEL4,5) repeat of the VNTR region (GRCh38 chr9:133,071,168-133,071,332).
Experimental evidence supports a Gain of Function, dominant negative mechanism of pathogenicity, in which certain frameshift variants cause the resulting protein to from toxic cellular aggregates (29233499). Crucially, an extended number of frameshifted repeats seem to be required to facilitate the formation of these aggregates (27650499, 38483348, 33862081). This is likely due to the increased presence of cysteine residues facilitating di-sulphide bonds, and the decreased presence of Threonine residuce that undergo O-glycosylation which is necessary for protein secretion. In addition, heterozygous NMD variants are common in gnomAD v4 for this gene (pLI = 0, o/e = 0.74), further arguing against dominant LoF as a pathogenic mechanism despite the potential for late onset and reduced penetrance.
Importantly, both more distal frameshift deletions, distal single base insertions (beyond repeat 7), and frameshift variants that result in a premature termination codon in the same repeat, have no strong evidence for pathogenicity to date as they do not result in toxic protein aggregation (38483348, 33862081). Some insertions in the proximal VNTR region, in particular in the first and fourth repeat (INS1, INS4), may confer an increased risk of pancreatitis, but evidence so far remains inconclusive (PMID:38483348). More distal single base insertions (beyond repeat 7) and distal deletions have been described as likely benign.
From a technical perspective, the region is challenging to map for short read NGS technologies due to the repetitive nature and high GC content. At least the five four repeats critical for MODY however are reasonably well covered in srWGS and WES data, and should be callable in routine testing. Although the fifth repeat does have increasing numbers of multimapping reads which may start to reduce sensitivity.Created: 6 Jan 2026, 10:22 a.m. | Last Modified: 6 Jan 2026, 10:29 a.m.
Panel Version: 0.92
Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Phenotypes
Maturity-onset diabetes of the young, type VIII, MIM#609812
Publications
Mode of pathogenicity
Other
All cases of monogenic diabetes convincingly attributed to this gene have been single base deletions in the proximal VNTR repeats that alter and shorten the VNTR repeat region and lead to the rare syndrome of autosomal dominant diabetes with exocrine pancreatic dysfunction with measurable fecal elastase deficiency or hereditary pancreatitis.
MODERATE rating ClinGen MODY expert panelCreated: 13 Nov 2023, 11:08 a.m. | Last Modified: 13 Nov 2023, 11:08 a.m.
Panel Version: 1.3
Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Comment when marking as ready: Agree, only frameshift mutations in the VNTR-containing exon 11 have evidence for pathogenicity.Created: 27 Feb 2020, 12:54 p.m. | Last Modified: 27 Feb 2020, 12:54 p.m.
Panel Version: 0.4
Current studies show only VNTR convincingly cause this condition, not SNVs
Single study (PMID;27650499) shows some protein consequence from SNVs, but their presence in patients is questionableCreated: 25 Feb 2020, 8:49 a.m. | Last Modified: 25 Feb 2020, 8:49 a.m.
Panel Version: 0.3
Phenotypes
Maturity-onset diabetes of the young, type VIII
Publications
Publications for gene: CEL were set to 19760265; 21784842; 27650499; 18544793; 17989309; 24062244; 16369531; 25160620
Mode of pathogenicity for gene: CEL was changed from to Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments
Gene: cel has been classified as Green List (High Evidence).
Tag technically challenging tag was added to gene: CEL.
Gene: cel has been classified as Amber List (Moderate Evidence).
Gene: cel has been classified as Amber List (Moderate Evidence).
gene: CEL was added gene: CEL was added to Monogenic diabetes. Sources: Expert Review Green,NHS GMS Mode of inheritance for gene: CEL was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: CEL were set to 19760265; 21784842; 27650499; 18544793; 17989309; 24062244; 16369531; 25160620 Phenotypes for gene: CEL were set to Diabetes and pancreatic exocrine dysfunction; Maturity-onset diabetes of the young, type VIII, 609812