PMC7350603_01
a. Picture of the proband with no somatic features suggestive of BWS. 1b. 18F-Dopa PET scan showed accentuated 18F-dopa uptake in the pancreatic body, with a lesser degree of diffused activity in pancreatic head and tail, suggestive of a focal lesion. 1c-e. Histology of resected pancreatic tissue. c. The pancreas shows preserved acinar architecture with prominent islets of Langerhans (arrowhead), consist of coalescing nests and trabeculae of endocrine cells. d. High power field showing some islets containing isolated, enlarged, hyperchromatic nuclei, which is over 2 times the size of the nuclei in the adjacent islet cells. e. Immunohistochemical stains confirmed the nests and trabeculae of endocrine cells are positive for neuroendocrine marker chromogranin and many of them express insulin by immunohistochemistry
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Fig1
Physical examination showed macrosomia but no other dysmorphic features (Fig. 1a). 18F-Dopa PET scan at 3 months of age showed accentuated 18F-dopa uptake in the pancreatic body compared with a lesser degree of diffuse activity in pancreatic head and tail, suggestive of a focal lesion (Fig. 1b). There were areas of coalescing nests and trabeculae (Fig. 1c) that were negative for p57 staining, suggestive of adenomatous hyperplasia; whilst some areas contained islets with isolated enlarged, hyperchromatic nuclei and exocrine acini at the periphery (Fig. 1d).
Sanger DNA sequencing and absolute quantitation by digital PCR analyses of ABCC8:c.1792C > T and allele difference plots of chromosome 11. a Sanger DNA sequencing results showed C:T allelic ratio in DNA extracted from peripheral blood and Pancreas 1A and 2A tissues of the proband. b The proportion of c.1792 T variant in mother, father and proband. The c.1792 T was absent in the mother and presence at 50% in father and proband blood DNA. Pancreas 1A and 2A DNA showed to have 88.8 and 70.6%. of c.1792 T. The proportion of c.1792 T in each DNA sample was averaged of 3 independent assays. Error bars: standard error mean. c Allele difference plots of chromosome 11 on DNA extracted from Pancreas 1A and 2A and from peripheral blood of proband and proband's parents. Red horizontal curly bracket and red vertical rectangle indicate the 17.44 Mb of AOH region in 11p15.5p15.1, arr [GRCh37] 11p15.5p15.1(230750_17671331)x 2 hmz, in Pancreas 1A and 2A. The affected SNPs in Pancreas 1A and 2A are shown in dark grey dots. High level of mosaicism is observed in Pancreas 2A. Vertical dotted line and arrow indicates the location of ABCC8 gene (chr11:17414431-17,498,392, human genome assembly: GRCh37) which is situated with in the AOH region (within red vertical rectangle). Inset (lower right) illustrates the segmental paternal UPD 11p and the location of c.1792C > T in the pancreas DNA, where the beige and white color shaded regions represents maternal and paternal inherited chromosome respectively
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Fig2
The proportion of the c.1792C and c.1792 T variant present in Pancreas 1A and 2A were of approximately 10%:90 and 30%:70%, respectively, estimated by peak height for the c.1792C and c.1792 T in the sequence chromatogram (Fig. 2a). Absolute quantitation by digital PCR analysis showed that the proportion of c.1792 T was approximately 88.9 and 70.6% in Pancreas 1A and 2A, respectively (Fig. 2b), which was concomitant to the level of mosaicism of pUPD11p region carrying the c.1792 T variant inherited from the father.  However, the pancreatic tissue showed a 17.44 Mb region of copy number neutral loss of heterozygosity (LOH) in 11p15.5-p15.1, suggesting segmental UPD 11, with a higher level of mosaicism for Pancreas 1A (~ 90%) compared to Pancreas 2A (~ 70%) (Fig. 2c) for the same region.