Fig. 1

Molecular genetic findings for Family 1. A Pedigree of Family 1. Dark purple (II-3, III-1): affected by BWS. Light purple (II-2): increased birth weight, but no additional features of BWS. B, E–G MS-MLPA results for members of Family 1. Each point in the plot represents a MLPA probe (circles and triangles: MS-MLPA probes for IC1 and IC2, respectively; squares: control probes). The Y-axis is the normalized peak ratio, with a normal range of 0.8–1.2 (dashed horizontal lines). MS-MLPA probes demonstrate hypermethylation (red), borderline hypermethylation (yellow), or normal methylation (green). Borderline hypermethylation is referred to as all four MS-MLPA probes of the same IC consistently trending up (i.e., peak ratio above 1.0) but not exceeding the cutoff of hypermethylation. The X-axis denotes fragment sizes of the MLPA probes. C Copy-number MLPA results for II-2. Each point in the plot represents a MLPA probe (circles: the two copy-number probes within the IC1 microdeletion; diamonds: other copy-number probes for IC1 and IC2; squares: control probes). The two circles are at 51.0% and 51.5%, consistent with a heterozygous deletion spanning these probes. D Gel electrophoresis and Sanger sequencing revealed a 1.8-kb IC1 microdeletion. Following PCR using the primer set 1 (see Methods), two bands, approximately 4.2 kb and 2.4 kb in size, were observed for II-2 (Individual 2 in Table 1) by gel electrophoresis. In contrast, only the 4.2-kb band was observed for the normal control. The genomic sequences (GRCh37/hg19) flanking the deletion are shown above the Sanger trace, with the dashed vertical line denoting the breakpoints according to the HGVS 3’ rule. The yellow-shaded nucleotides denote mismatches with the Sanger trace, while the cyan-shaded nucleotides denote heterozygous sites in the Sanger trace. The deletion breakpoints were determined based on the cyan-shaded nucleotides, where they first appear in the Sanger trace (see Figure S1 for details)