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BackgroundDiagnosis of monogenic as well as atypical forms of diabetes mellitus has important clinical implications for their specific diagnosis, prognosis, and targeted treatment. Single gene mutations that affect beta-cell function represent 1-2% of all cases of diabetes. However, phenotypic heterogeneity and lack of family history of diabetes can limit the diagnosis of monogenic forms of diabetes. Next-generation sequencing technologies provide an excellent opportunity to screen large numbers of individuals with a diagnosis of diabetes for mutations in disease-associated genes.MethodsWe utilized a targeted sequencing approach using the Illumina HiSeq to perform a case-control sequencing study of 22 monogenic diabetes genes in 4016 individuals with type 2 diabetes (including 1346 individuals diagnosed before the age of 40 years) and 2872 controls. We analyzed protein-coding variants identified from the sequence data and compared the frequencies of pathogenic variants (protein-truncating variants and missense variants) between the cases and controls.ResultsA total of 40 individuals with diabetes (1.8% of early onset sub-group and 0.6% of adult onset sub-group) were carriers of known pathogenic missense variants in the GCK, HNF1A, HNF4A, ABCC8, and INS genes. In addition, heterozygous protein truncating mutations were detected in the GCK, HNF1A, and HNF1B genes in seven individuals with diabetes. Rare missense mutations in the GCK gene were significantly over-represented in individuals with diabetes (0.5% carrier frequency) compared to controls (0.035%). One individual with early onset diabetes was homozygous for a rare pathogenic missense variant in the WFS1 gene but did not have the additional phenotypes associated with Wolfram syndrome.ConclusionTargeted sequencing of genes linked with monogenic diabetes can identify disease-relevant mutations in individuals diagnosed with type 2 diabetes not suspected of having monogenic forms of the disease. Our data suggests that GCK-MODY frequently masquerades as classical type 2 diabetes. The results confirm that MODY is under-diagnosed, particularly in individuals presenting with early onset diabetes and clinically labeled as type 2 diabetes; thus, sequencing of all monogenic diabetes genes should be routinely considered in such individuals. Genetic information can provide a specific diagnosis, inform disease prognosis and may help to better stratify treatment plans.

PurposeNail-Patella syndrome is a dominantly inherited genetic disorder characterized by abnormalities of the nails, knees, elbows, and pelvis. Nail abnormalities are the most constant feature of Nail-Patella syndrome. Pathogenic mutations in a single gene, LMX1B, a mesenchymal determinant of dorsal-ventral patterning, explain approximately 95% of Nail-Patella syndrome cases. However, 5% of cases remain unexplained.MethodsHere, we present exome sequencing and analysis of four generations of a family with a dominantly inherited Nail-Patella-like disorder (nail dysplasia with some features of Nail-Patella syndrome) who tested negative for LMX1B mutation.ResultsWe identify a loss-of-function mutation in WIF1 (NM_007191 p.W15*), which is involved in mesoderm segmentation, as the suspected cause of the Nail-Patella-like disorder observed in this family.ConclusionsMutation of WIF1 is a potential novel cause of a Nail-Patella-like disorder. Testing of additional patients negative for LMX1B mutation is needed to confirm this finding and further clarify the phenotype.Genet Med advance online publication 06 April 2017.

Author(s): Hayden C. Metsky [1, 2]; Christian B. Matranga [1]; Shirlee Wohl [1, 3]; Stephen F. Schaffner [1, 3, 4]; Catherine A. Freije [1, 3]; Sarah M. Winnicki [1]; Kendra [...]

Author(s): Nathan D. Grubaugh [1]; Jason T. Ladner [2]; Moritz U. G. Kraemer [3, 4, 5]; Gytis Dudas [6]; Amanda L. Tan [7]; Karthik Gangavarapu [1]; Michael R. Wiley [2, [...]

Early detection of pancreatic cancer has been shown to improve patient survival rates. However, effective early detection tools to detect pancreatic cancer do not currently exist. The Avantect Pancreatic Cancer Test, leveraging the 5-hydroxymethylation [5-hydroxymethylcytosine (5hmC)] signatures in cell-free DNA, was developed and analytically validated to address this unmet need. We report a comprehensive analytical validation study encompassing precision, sample stability, limit of detection, interfering substance studies, and a comparison with an alternative method. The assay performance on an independent case-control patient cohort was previously reported with a sensitivity for early-stage (stage I/II) pancreatic cancer of 68.3% (95% CI, 51.9%-81.9%) and an overall specificity of 96.9% (95% CI, 96.1%-97.7%). Precision studies showed a cancer classification of 100% concordance in biological replicates. The sample stability studies revealed stable assay performance for up to 7 days after blood collection. The limit of detection studies revealed equal results between early- and late-stage cancer samples, emphasizing strong early-stage performance characteristics. Comparisons of concordance of the Avantect assay with the enzymatic methyl sequencing (EM-Seq) method, which measures both methylation (5-methylcytosine) and 5hmC, were >95% for all samples tested. The Avantect Pancreatic Cancer Test showed strong analytical validation in multiple validation studies required for laboratory-developed test accreditation. The comparison of 5hmC versus EM-Seq further validated the 5hmC approach as a robust and reproducible assay., Competing Interests: Disclosure Statement All authors are employees of ClearNote Health., (Copyright © 2024 Association for Molecular Pathology and American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)