Exome Sequencing Identifies Biallelic MSH3 Germline Mutations as a Recessive Subtype of Colorectal Adenomatous Polyposis.

In ∼30% of families affected by colorectal adenomatous polyposis, no germline mutations have been identified in the previously implicated genes APC, MUTYH, POLE, POLD1, and NTHL1, although a hereditary etiology is likely. To uncover further genes with high-penetrance causative mutations, we performed exome sequencing of leukocyte DNA from 102 unrelated individuals with unexplained adenomatous polyposis. We identified two unrelated individuals with differing compound-heterozygous loss-of-function (LoF) germline mutations in the mismatch-repair gene MSH3.

Array-based molecular karyotyping in fetuses with isolated brain malformations identifies disease-causing CNVs.

Background: The overall birth prevalence for congenital malformations of the central nervous system (CNS) among Europeans may be as high as 1 in 100 live births. The etiological factors remain largely unknown. The aim of this study was to detect causative copy number variations (CNVs) in fetuses of terminated pregnancies with prenatally detected isolated brain malformations.

Frequency and phenotypic spectrum of germline mutations in POLE and seven other polymerase genes in 266 patients with colorectal adenomas and carcinomas.

In a number of families with colorectal adenomatous polyposis or suspected Lynch syndrome/HNPCC, no germline alteration in the APC, MUTYH, or mismatch repair (MMR) genes are found. Missense mutations in the polymerase genes POLE and POLD1 have recently been identified as rare cause of multiple colorectal adenomas and carcinomas, a condition termed polymerase proofreading-associated polyposis (PPAP). The aim of the present study was to evaluate the clinical relevance and phenotypic spectrum of polymerase germline mutations.

Genome-wide CNV analysis in 221 unrelated patients and targeted high-throughput sequencing reveal novel causative candidate genes for colorectal adenomatous polyposis.

To uncover novel causative genes in patients with unexplained adenomatous polyposis, a model disease for colorectal cancer, we performed a genome-wide analysis of germline copy number variants (CNV) in a large, well characterized APC and MUTYH mutation negative patient cohort followed by a targeted next generation sequencing (NGS) approach. Genomic DNA from 221 unrelated German patients was genotyped on high-resolution SNP arrays. Putative CNVs were filtered according to stringent criteria, compared with those of 531 population-based German controls, and validated by qPCR.

MUTYH-associated polyposis (MAP): evidence for the origin of the common European mutations p.Tyr179Cys and p.Gly396Asp by founder events.

MUTYH-associated polyposis (MAP) is an autosomal recessive adenomatous polyposis caused by biallelic germline mutations of the base-excision-repair gene MUTYH. In MAP patients of European origin, the combined allele frequency of the mutations p.Tyr179Cys and p.

Deep intronic APC mutations explain a substantial proportion of patients with familial or early-onset adenomatous polyposis.

To uncover pathogenic deep intronic variants in patients with colorectal adenomatous polyposis, in whom no germline mutation in the APC or MUTYH genes can be identified by routine diagnostics, we performed a systematic APC messenger RNA analysis in 125 unrelated mutation-negative cases. Overall, we identified aberrant transcripts in 8% of the patients (familial cases 30%; early-onset manifestation 21%). In eight of them, two different out-of-frame pseudoexons were found consisting of a 167-bp insertion from intron 4 in five families with a shared founder haplotype and a 83-bp insertion from intron 10 in three patients.

Microduplications at 22q11.21 are associated with non-syndromic classic bladder exstrophy.

The exstrophy-epispadias complex (EEC) comprises a spectrum of urogenital anomalies in which part or all of the distal urinary tract fails to close. The present study aimed to identify microaberrations characterized by loss or gain of genomic material that contribute to the EEC at a genome-wide level. Molecular karyotyping, utilizing 549,839 single nucleotide polymorphisms (SNPs) with an average spacing of 5.

Analysis of rare APC variants at the mRNA level: six pathogenic mutations and literature review.

In monogenic disorders, the functional evaluation of rare, unclassified variants helps to assess their pathogenic relevance and can improve differential diagnosis and predictive testing. We characterized six rare APC variants in patients with familial adenomatous polyposis at the mRNA level. APC variants c.

Somatic APC mosaicism: a frequent cause of familial adenomatous polyposis (FAP).

Somatic mutational mosaicism presents a challenge for both molecular and clinical diagnostics and may contribute to deviations from predicted genotype-phenotype correlations. During APC mutation screening in 1,248 unrelated patients with familial adenomatous polyposis (FAP), we identified 75 cases with an assumed or confirmed de novo mutation. Prescreening methods (protein truncation test [PTT], DHPLC) indicated the presence of somatic mosaicism in eight cases (11%).

A complex rearrangement in the APC gene uncovered by multiplex ligation-dependent probe amplification.

Germline mutations in the tumor suppressor gene APC are the underlying cause of familial adenomatous polyposis, an autosomal-dominant cancer predisposition syndrome of the colorectum. Here, we describe a complex pathogenic rearrangement in the APC gene that was detected during deletion screening and transmitted throughout at least three generations. The rearrangement consists of a deletion of 604 bp in intron 4 that impairs the binding site of the reverse primer for exon 4 and of an insertion of 119 bp in exon 4 that interferes with the binding site of the multiplex ligation-dependent probe amplification (MLPA) probes for exon 4.

High proportion of large genomic STK11 deletions in Peutz-Jeghers syndrome.

Germline mutations in the STK11 gene have been identified in 10-70% of patients with Peutz-Jeghers syndrome (PJS), an autosomal-dominant hamartomatous polyposis syndrome. A second locus was assumed in a large proportion of PJS patients. To date, STK11 alterations comprise mainly point mutations; only a small number of large deletions have been reported.