Diversity of the clinical presentation of the MMR gene biallelic mutations.

Constitutional mismatch repair-deficiency, due to biallelic mutations of MMR genes, results in a tumour spectrum characterized by leukaemias, lymphomas, brain tumours and adenocarcinomas of the gastro-intestinal tract, occurring mostly in childhood. We report here two families illustrating the phenotypic diversity associated with biallelic MMR mutations. In the first family, two siblings developed six malignancies including glioblastoma, lymphoblastic T cell lymphoma, rectal and small bowel adenocarcinoma with onset as early as 6 years of age.

Partial duplications of the MSH2 and MLH1 genes in hereditary nonpolyposis colorectal cancer.

Numerous reports have highlighted the contribution of MSH2 and MLH1 genomic deletions to hereditary nonpolyposis colorectal cancer (HNPCC) or Lynch's syndrome, but genomic duplications of these genes have been rarely reported. Using quantitative multiplex PCR of short fluorescent fragments (QMPSF), 962 and 611 index cases were, respectively, screened for MSH2 and MLH1 genomic rearrangements. This allowed us to detect, in 11 families, seven MSH2 duplications affecting exons 1-2-3, exons 4-5-6, exon 7, exons 7-8, exons 9-10, exon 11, and exon 15, and three MLH1 duplications affecting exons 2-3, exon 4 and exons 6-7-8.

Biological effects of four PSEN1 gene mutations causing Alzheimer disease with spastic paraparesis and cotton wool plaques.

We describe the biological consequences on PSEN1 exons 8 or 9 splicing and Abeta peptides production of four PSEN1 mutations associated with a phenotypic variant of Alzheimer disease, which includes cotton wool plaques and spastic paraparesis (CWP/SP). Two of these mutations (c.869-22_869-23ins18 and c.

The 5' region of the MSH2 gene involved in hereditary non-polyposis colorectal cancer contains a high density of recombinogenic sequences.

MSH2 rearrangements are involved in approximately 10% of hereditary non-polyposis colorectal cancer (HNPCC) families, and in most of the rearrangements, exon 1 is deleted. We scanned by quantitative multiplex polymerase chain reaction (PCR) of short fluorescent fragments (QMPSF) 200 kb of genomic sequences upstream of the MSH2 transcription initiation site in 21 HNPCC families with exon 1 deletions. This QMPSF scan revealed 12 distinct 5' breakpoints located up to 200 kb upstream of the MSH2 transcription initiation site.

Analysis of the allele-specific expression of the mismatch repair gene MLH1 using a simple DHPLC-Based Method.

Quantitative measures of allele-specific gene expression allow the indirect detection of mutations or sequence variants in regulatory elements or in other non-coding regions that may result in significant physiological or pathological changes of gene expression and may contribute to Mendelian or multifactorial disorders. We have devised a simple method, based on RT-PCR and single nucleotide primer extension (SNuPE) with unlabelled dideoxynucleotides, followed by DHPLC (denaturing high performance liquid chromatography). We established optimal conditions for separation of the extended products corresponding to the alleles of the c.

Screening for TP53 rearrangements in families with the Li-Fraumeni syndrome reveals a complete deletion of the TP53 gene.

The absence of detectable germline TP53 mutations in a fraction of families with Li-Fraumeni syndrome (LFS) has suggested the involvement of other genes, but this hypothesis remains controversial. The density of Alu repeats within the TP53 gene led us to search genomic rearrangements of TP53 in families without detectable TP53 mutation. To this aim, we adapted the quantitative multiplex PCR of short fluorescent fragments (QMPSF) method to the analysis of the 11 exons of TP53.

MSH2 in contrast to MLH1 and MSH6 is frequently inactivated by exonic and promoter rearrangements in hereditary nonpolyposis colorectal cancer.

To estimate the relative frequency of mismatch repair genes, rearrangements in hereditary nonpolyposis colorectal cancer (HNPCC) families without detectable mutations in MSH2 or MLH1, we have analyzed by multiplex PCR of short fluorescent fragments MSH2, MLH1, and MSH6 in 61 families, either fulfilling Amsterdam criteria or including cases of multiple primary cancers belonging to the HNPCC spectrum. We detected 13 different genomic rearrangements of MSH2 in 14 families (23%), whereas we found no rearrangement of MLH1 and MSH6. Analysis of 31 other families, partially meeting Amsterdam criteria, revealed no additional rearrangement of MSH2.