The Methylation Status in the Chromosome 11p15.5 Region and Metabolic Disorders in Children with Syndromic and Nonsyndromic Intrauterine Growth Restriction

Loss of methylation (LoM) of the imprinting control region 1 (ICR1) in the chromosome 11p15.5 domain is detected in patients with Silver-Russell syndrome (SRS), characterized by asymmetric pre- and postnatal growth restriction, and typical craniofacial features. The patients with intrauterine growth restriction (IUGR) possess a high risk for adult metabolic problems. This study is aimed to investigate the methylation levels of the chromosome 11p15.5 region and metabolic problems in children with syndromic and nonsyndromic IUGR. Methylation analysis was performed for chromosome 11p15.5 in 49 patients (33 with suspected SRS and 16 nonsyndromic IUGR) with Netchine-Harbison clinical scoring (NHCS); uniparental disomy for chromosomes 6, 7, 14, and 20 was evaluated for those who were negative. LoM of ICR1 was detected in 14 of 33 suspected SRS patients with 3 or more criteria of NHCS, 5 had borderline LoM. Maternal uniparental disomy of the chromosomes 7 and 14 was found in 2 patients. The overall detection rate of SRS was 45.5%. While clinical findings were similar in patients with LoM and borderline LoM of ICR1, typical craniofacial findings were significantly less in the patients with normal methylation. Methylation patterns were not found to be impaired in the nonsyndromic IUGR group. Metabolic complications were evaluated in a total of 63 patients including 33 SRS-suspicious, 16 nonsyndromic IUGR, and 14 patients with 3M or SHORT syndrome. Increased rates of hypercalciuria, insulin resistance, and dyslipidemia were detected in patients with both syndromic and nonsyndromic IUGR. We would like to emphasize that detecting typical facial findings is effective in the diagnosis of SRS and paying attention to metabolic problems in the follow-up of patients with IUGR is recommended.

Paternal Uniparental Disomy of the Entire Chromosome 20 in a Child with Beckwith-Wiedemann Syndrome

Epigenetic alterations at imprinted genes on different chromosomes have been linked to several imprinting disorders (IDs) such as Beckwith-Wiedemann syndrome (BWS) and pseudohypoparathyroidism type 1b (PHP1b). Here, we present a male patient with these two distinct IDs caused by two independent mechanisms-loss of methylation (LOM) at chromosome 11p15.5 associated with multi-locus imprinting disturbances (MLID and paternal uniparental disomy of chromosome 20 (patUPD20). A clinical diagnosis of BWS was made based on the clinical features of macrosomia, macroglossia, and umbilical hernia. The diagnosis of PHP1b was supported by the presence of reduced growth velocity and mild learning disability as well as hypocalcemia and hyperphosphatemia at 14 years of age. Molecular analyses, including genome-wide DNA methylation (Illumina 450k array), bisulfite pyrosequencing, single nucleotide polymorphism (SNP) array and microsatellite analysis, demonstrated loss of methylation (LOM) at IC2 on chromosome 11p15.5, and paternal isodisomy of the entire chromosome 20. In addition, imprinting disturbances were noted at the differentially methylated regions (DMRs) associated with DIRAS3 on chromosome 1 and PLAGL1 on chromosome 6. This is the first case report of PHP1b due to patUPD20 diagnosed in a BWS patient with LOM at IC2 demonstrating etiologic heterogeneity for multiple imprinting disorders in a single individual.

A Beckwith-Wiedemann Syndrome Case with de novo 24 Mb Duplication of Chromosome 11p15.5-14.3

BackgroundMolecular genetic testing for the 11p15-associated imprinting disorder Beckwith-Wiedemann syndrome(BWS) is challenging because of the molecular heterogeneity and complexity of the affected imprinted regions. An accurate diagnosis of BWS requires a complete molecular method to analyze epigenetic changes.Case presentationWe reported a Chinese case with BWS detected by SNP array analysis and methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA). The genetic analysis showed a de nove duplication of 24 Mb at 11p15.5-14.3 is much longer than ever reported. MS-MLPA showed copy number changes with a peak height ratio value of 1.5(three copies) at 11p15. The duplication of paternal origin withincrease of methylation index of 0.68 at H19 and decreased methylation index of 0.37 at KCNQ1OT1.ConclusionCombined chromosome microarray analysis and methylation profiling provided reliable diagnosis for this paternally derived duplication of BWS. The phenotype associated with 11p15 duplications depends on the size, genetic content, parental inheritance and imprinting status. Identification of these rare duplications is crucial for genetic counselling.

Androgenetic Complete Hydatidiform Moles With p57KIP2-Positive Immunostaining

Objectives Complete hydatidiform moles (CHMs) are androgenetic and have a high rate of progression to gestational trophoblastic neoplasia (GTN). CHMs are negative when immunostained for p57KIP2 protein, the product of the maternally expressed gene on chromosome 11p15.5, whereas biparental partial hydatidiform moles and hydropic abortion are positive for p57KIP2. This study presents two cases of p57KIP2-positive androgenetic CHMs and explores the cause of this inconsistency. Methods Androgenetic CHMs were diagnosed using multiplex short tandem repeat polymorphism analysis. Single-nucleotide polymorphism arrays were performed for molecular karyotyping. Results Among the consecutive 188 androgenetic CHMs, two cases were positive for p57KIP2. The first case remitted spontaneously, whereas the second case developed into low-risk GTN. The first case was positive for p57KIP2 in all villi. The karyotype was 48,XX,+7,+11, with the additional chromosome 11 confirmed to be of maternal origin. The second case presented a mosaic of both positively and negatively stained villi. The karyotype was 46,XX. Conclusions The cause of one of the CHMs was trisomy with an additional maternal chromosome 11. Although rare, the confirmation of p57KIP2-positive androgenetic CHM status is necessary to manage GTN risk.

Improved molecular detection of mosaicism in Beckwith-Wiedemann Syndrome

BackgroundBeckwith-Wiedemann Syndrome (BWS) is characterised by overgrowth and tumour predisposition. While multiple epigenetic and genetic mechanisms cause BWS, the majority are caused by methylation defects in imprinting control regions on chromosome 11p15.5. Disease-causing methylation defects are often mosaic within affected individuals. Phenotypic variability among individuals with chromosome 11p15.5 defects and tissue mosaicism led to the definition of the Beckwith-Wiedemann Spectrum (BWSp). Molecular diagnosis of BWSp requires use of multiple sensitive diagnostic techniques to reliably detect low-level aberrations.MethodsMultimodal BWS diagnostic testing was performed on samples from 1057 individuals. Testing included use of a sensitive qRT-PCR-based quantitation method enabling identification of low-level mosaic disease, identification of CNVs within 11p15.5 via array comparative genomic hybridisation or qRT-PCR, and Sanger sequencing of CDKN1C.ResultsA molecular diagnosis was confirmed for 27.4% of individuals tested, of whom 43.4% had mosaic disease. The presence of a single cardinal feature was associated with a molecular diagnosis of BWSp in 20% of cases. Additionally, significant differences in the prevalence of mosaic disease among BWS molecular subtypes were identified. Finally, the diagnostic yield obtained by testing solid tissue samples from individuals with negative blood testing results shows improved molecular diagnosis.ConclusionThis study highlights the prevalence of mosaic disease among individuals with BWSp and the increases in diagnostic yield obtained via testing both blood and solid tissue samples from affected individuals. Additionally, the results establish the presence of a molecular diagnosis in individuals with very subtle features of BWSp.

Replication of GWAS Loci Revealed an Increased Risk of BET1L and H19 Polymorphisms with Intracranial Aneurysm

A genome-wide association study (GWAS) identified that BET1L rs2280543 at chromosome 11p15.5 was a susceptibility loci of intracranial aneurysm (IA). Long noncoding RNA H19, located in this region, was reported to play a crucial role in the formation of IA. In this study, we aimed to examine whether BET1L rs2280543 and potentially functional polymorphisms in H19 influence the risk of IA. A hospital-based case-control study was performed involving 542 IA patients and 588 age- and gender-matched controls. The BET1L rs2280543 and H19 polymorphisms were genotyped using the TaqMan assay. The BET1L rs2280543 CT, CT/TT genotypes, and T allele were associated with an increased risk of IA (CT vs. CC, adjusted OR=1.43, 95% CI: 1.08-1.90, P=0.01; CT/TT vs. CC, adjusted OR=1.48, 95% CI: 1.12-1.94, P=0.005; and T vs. C, adjusted OR=1.44, 95% CI: 1.13-1.83, P=0.003). Similarly, the H19 rs217727 TT genotype and T allele were associated with an increased risk of IA (TT vs. CC, adjusted OR=1.90, 95% CI: 1.35-2.67, P<0.001; T vs. C, adjusted OR=1.38, 95% CI: 1.16-1.64, P<0.001). Combined analyses revealed that the rs2280543 CC-rs217727 CT/TT, rs2280543 CT/TT-rs2735971 GG, and rs217727 CT/TT-rs2735971 GG genotypes were related to the risk of IA. Interaction analysis showed that the 3-loci model of rs2280543-rs217727-rs2839698 contributed to an increased risk of IA. These findings suggest that the GWAS-discovered risk loci BET1L rs2280543 may increase IA susceptibility by interacting with lncRNA H19.

A 4-Year-Old Boy with Beckwith Wiedemann Syndrome (BWS)

Objectives: Molecular characterization of a patient with BWS. Clinical presentation and intervention: A 4-year-old boy with overgrowth (weight above 99th and height at 99th percentile) had longitudinal hemihypertrophy of the tongue and left cheek. In addition, there was a difference of one centimeter in the circumference of the left and right leg. Molecular genetic analysis revealed hypomethylation of KvDRM1 (LIT1) in the imprinting control region-2 (ICR2) on chromosome 11p15.5 and a normal methylation pattern of the H19-differentially methylated region (H19-DMR) in the ICR1. The estimated tumor risk was 1-5%. Conclusion: This patient with clinical characteristics of BWS has an imprinting defect associated with a low risk of embryonal tumors.