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Ikaros is a mutational target for lymphomagenesis in Mlh1-deficient mice.

Deficiencies in DNA mismatch repair (MMR) result in replication errors within key tumor suppressor genes or oncogenes, and cause hereditary nonpolyposis colorectal cancer (HNPCC). Hematological malignancy with microsatellite instability is also associated with defective MMR, but little is known about the target genes for MMR. Here we identified Ikaros, a master transcription factor of lymphoid lineage commitment and differentiation, as a mutational target in spontaneous and radiation-induced T-cell lymphomas in Mlh1-deficient mice. Three quarters of lymphomas lacked Ikaros protein expression, which resulted from a frameshift mutation that created a stop codon. Mononucleotide repeat sequences at 1029-1034(C)6 and 1567-1572(G)6 in Ikaros were mutational hot spots with a one-base deletion occurring with a frequency of 45 and 50%, respectively. Point mutations and splicing alterations were also observed. In total, 85% of the lymphomas showed aberrations in Ikaros. The characteristic of Mlh1-deficient lymphomas is harboring of multiple mutations simultaneously in the same tumor, displaying a combination of two frameshift mutations at different repeats, frameshift and point mutations, and/or deletion mutations. This is the first report of Ikaros mutations coupled with Mlh1 deficiency in lymphomagenesis.

Adaptor Proteins, Signal Transducing↗

Characterization of a germline mosaicism in families with Lowe syndrome, and identification of seven novel mutations in the OCRL1 gene.

The oculocerebrorenal syndrome of Lowe (OCRL) is an X-linked disorder characterized by major abnormalities of eyes, nervous system, and kidneys. Mutations in the OCRL1 gene have been associated with the disease. OCRL1 encodes a phosphatidylinositol 4, 5-biphosphate (PtdIns[4,5]P2) 5-phosphatase. We have examined the OCRL1 gene in eight unrelated patients with OCRL and have found seven new mutations and one recurrent in-frame deletion. Among the new mutations, two nonsense mutations (R317X and E558X) and three other frameshift mutations caused premature termination of the protein. A missense mutation, R483G, was located in the highly conserved PtdIns(4,5)P2 5-phosphatase domain. Finally, one frameshift mutation, 2799delC, modifies the C-terminal part of OCRL1, with an extension of six amino acids. Altogether, 70% of missense mutations are located in exon 15, and 52% of all mutations cluster in exons 11-15. We also identified two new microsatellite markers for the OCRL1 locus, and we detected a germline mosaicism in one family. This observation has direct implications for genetic counseling of Lowe syndrome families.

Amino Acid Sequence↗

[The mutagenic effect of the recombinant plasmid pBR322ins carrying a native and a modified human insulin gene].

The mutagenic activity of pBR322 bacterial plasmid DNA and of pBR322ins and pBR322insN recombinant plasmid DNAs has been investigated in Blld-ii-FAF 28 line cultivated fibroblasts of Chinese hamster. The pBR322 bacterial plasmid DNA is shown to induce no resistant mutations to 6-mercaptopurine; the pBR322insN (the frameshift mutation in human insulin gene; this gene is supposed to have no expression in the cells because of frameshift mutation) induces neither such mutations as well. The pBR322ins recombinant plasmid carrying the native human insulin gene induces the gene mutations in this system. The influence of the insulin gene structure on the gene mutations induction is taken into account. The results obtained and the data of other authors illustrate a great interest of recombinant DNA molecules carrying transgenes in the field of mutation research.

Animals↗

High incidence of the CD8/9 (+G) beta 0-thalassemia mutation in Spain.

BACKGROUND AND OBJECTIVE: In Spain, as in other Mediterranean regions the most common beta-thalassemia mutations are due to point mutations in gene regions that are critical for production of mRNA, such as [IVS-I-nt1 (G-->A), IVS-I-nt6 (T-->C), IVS-I-nt110 (G-->A)] which interrupt normal RNA processing or nonsense mutations [CD39 (C-->T)] which interrupt the translation of mRNA. The frameshift mutation CD8/9 (+G) is a very common allele in Asian Indians but is rare in the Mediterranean regions in which isolated alleles with this mutation have been found in Israel, Greece, Portugal and Turkey. DESIGN AND METHODS: We performed a molecular analysis of 175 chromosomes corresponding to 233 beta-thalassemia patients (221 heterozygous, 10 homozygous and 2 compound heterozygous) who belong to 169 Spanish families. The study of beta-thalassemia was made by PCR-ARMS, the alpha genes by Southern blot, the phenotype of Hb Lepore by enzymatic amplification and the presence of -158 gamma G C-->T mutation by PCR and digestion with the restriction enzyme XmnL. RESULTS: Twenty of these 233 patients showed the beta-thalassemia mutation CD8/9 (+G) (17 were heterozygous, 2 homozygous and in one patient the mutation was associated with a structural variant Hb Lepore Boston). INTERPRETATION AND CONCLUSIONS: These data reveal the heterogeneity of beta-thalassemia in Spain and the relatively high frequency (8.6%) of the frameshift mutation CD8/9 (+G). It is surprising that homozygotes for beta zero-thalassemia due to this mutation with very high Hb F values (around 90%) present a phenotype of intermediate thalassemia.

CD8 Antigens↗

A novel frameshift founder mutation in the cytochrome P450 1B1 (CYP1B1) gene is associated with primary congenital glaucoma in Morocco.

Primary congenital glaucoma (PCG) is a heterogeneous autosomal recessive disorder caused by unknown developmental defect(s) of the anterior chamber of the eye. A member of the cytochrome P450 gene family, CYP1B1, was found to be mutated in PCG patients in different populations, albeit to a variable extent. In this study, CYP1B1 mutations were searched for in 32 unrelated PCG patients from Morocco. Two mutations were detected in 11 (34%) patients. One, 4339delG, is novel and causes a frameshift at residue 179. The other, G61E, was previously found in patients from Turkey and Saudi Arabia. Seven patients were homozygous for 4339delG and two other patients for G61E, whereas the two remaining patients were compound heterozygotes. The close association of 4339delG with a rare allele of D2S177, a microsatellite marker located 270 kb upstream of CYP1B1, strongly suggested a founder effect for 4339delG. The occurrence of this mutation was tentatively dated at between 900 and 1700 years ago. Typing 4339delG and G61E mutations should help to prevent blindness resulting from a delayed diagnosis of PCG in Morocco.

Aryl Hydrocarbon Hydroxylases↗

Mutation hot spots in the canine herpesvirus thymidine kinase gene.

The guanine and cytosine content (GC-content) of alpha-herpesvirus genes are highly variable despite similar genome structures. It is known that drug resistant HSV, which has the genome with a high GC-content (approximately 70%), commonly includes frameshift mutations in homopolymer stretches of guanine (G) and cytosine (C) within the thymidine kinase (TK) gene. However, whether such mutation hotspots exist in the TK gene of canine herpesvirus (CHV) which has a low GC-content was unknown. In this study, we investigated mutations in the TK gene of CHV. CHV was passaged in the presence of iodo-deoxyuridine (IDU), and IDU-resistant clones were isolated. In all IDU-resistant virus clones, mutations in the TK gene were observed. The majority of these mutations were frameshift mutations of an adenine (A) insertion or deletion within either of 2 stretches of eight A's in the TK gene. It was demonstrated that CHV TK mutations frequently occur at a limited number of hot spots within long homopolymer nucleotide stretches.

Animals↗

Mutational spectrum of ICR-191 at the hprt locus in human lymphoblastoid cells.

Human TK6 lymphoblasts were treated with the acridine derivative ICR-191, and mutants at the hprt locus were isolated. Mutant hprt cDNA was reverse-transcribed from mRNA, amplified by polymerase chain reaction (PCR), and sequenced. Additions of single G:C base pairs (+1 frameshift mutations) in repetitive G:C sequences were found in 82% (32/39) of the mutants. Sixteen of the +1 frameshifts analyzed were located in a single sequence of six consecutive guanine bases in exon 3. The remaining +1 frameshifts occurred at six different GGG sequences (14 mutants) and a single GGGG sequence (2 mutants) in other hprt exons. The repetitive guanine sequences that underwent frameshift mutagenesis were located in both the transcribed and nontranscribed strands of hprt. No single base deletions (-1 frameshift mutations) were observed. Base substitutions were observed in 13% (5/39) of the clones analyzed and occurred at both G:C and A:T bases. Loss of exon 4 from the cDNA was also observed in 5% (2/39) of the mutants. Hprt mutants containing seven consecutive guanines (produced from a +1 frameshift in a GGGGGG sequence) were treated with ICR-191 and wild-type revertants selected in CHAT medium. Revertants were recovered at a frequency of approximately 10(-7) and contained the wild-type sequence (GGGGGG) in all clones analyzed. The observed frequency of ICR-191-induced-1 frameshift reversion in the GGGGGGG sequence was approximately 500-fold lower than the estimated frequency of +1 frameshifts observed in the wild-type GGGGGG sequence following the same ICR-191 treatment. These results suggest that ICR-191 produces predominantly +1 frameshift mutations at the hprt locus in human cells.

Aminacrine↗

GJB2 (Cx26) gene mutations in Chinese patients with congenital sensorineural deafness and a report of one novel mutation.

BACKGROUND: Mutations in GJB2 gene are a major cause of autosomal recessive congenital hearing loss and the cause in some rare cases of the autosomal dominant form. The purpose of this study was to investigate the frequency and the features of GJB2 mutations in the Chinese patients with congenital sensorineural deafness. METHODS: Using PCR amplifying the entire coding region of GJB2 gene and direct DNA sequencing to analyze mutations in this gene among unrelated 69 cases with autosomal recessive congenital nonsyndromic deafness and 27 cases of dominant congenital deafness and 35 sporadic cases. We also detected mutations in GJB2 in 100 control subjects with normal hearing. RESULTS: 17.4% (12/69) of the probands in the autosomal recessive, 7.4% (2/27) of dominant families and 5.7% (2/35) of the sporadic congenital deafness patients had deafness-causing mutations in GJB2, respectively. Nine types of the mutations in GJB2 were detected in the recessive and sporadic group. They consisted of five types of polymorphism, and four types of deafness-causing mutation with homozygous 35delG in 1 sporadic (1/35), and 235delC frameshift mutation in 1 sporadic (homozygotes) and 10 recessive patients (2 heterozygotes and 8 homozygotes), and homozygous 442G-->A missense mutation and homozygous 465T-->A nonsense mutation in 1 different recessive proband, respectively. The 465T-->A that related to recessive deafness was a novel mutation found by this study. The homozygous (10/69, 14.5%) and the heterozygous (2/69, 2.9%) GJB2 mutation in the recessive patients (12/69, 17.4%) and the homozygotes in the sporadic patient (2/35, 5.7%) all had congenital severe to profound sensorineural hearing loss. 511G-->A missense mutation and 299-300delAT frameshift mutation were found in two autosomal dominant congenital deafness families (2/27, 7.4%). The total mutation frequency of GJB2 was 12.2% (16/131) in the Chinese patients with congenital sensorineural deafness and 235delC was the most common deafness-causing mutation. Six types of mutation-5 types of polymorphism and 1 type of heterozygous deletion (235delC) mutation were found in the 100 control subjects. The carry rate of the most frequent type of mutation 235delC was 0.5% in the controls (1/200 alleles). 109G-->A was the most frequent (15/100, 15%) and 79G-->A was the second common (8/100, 8%) polymorphism in this population. CONCLUSIONS: The general mutation rate of GJB2 is 12.2% (16/131) and the 235delC is the most common type of deafness-causing mutation in Chinese patients with congenital hearing loss. 465T-->A nonsense mutation that is associated to autosomal recessive deafness is a novel mutation found by this screening. 511G-->A and 299-300delAT mutations contribute to autosomal dominant hearing loss. The study further supports the view that the common types of mutation in GJB2 according to different ethnic background and that the mutation prevalence in the East Asian deafness population is lower than that in the white population.

Connexin 26↗

Mutations in SOX9, the gene responsible for Campomelic dysplasia and autosomal sex reversal.

Campomelic dysplasia (CD) is a skeletal malformation syndrome frequently accompanied by 46,XY sex reversal. A mutation-screening strategy using SSCP was employed to identify mutations in SOX9, the chromosome 17q24 gene responsible for CD and autosomal sex reversal in man. We have screened seven CD patients with no cytologically detectable chromosomal aberrations and two CD patients with chromosome 17 rearrangements for mutations in the entire open reading frame of SOX9. Five different mutations have been identified in six CD patients: two missense mutations in the SOX9 putative DNA binding domain (high mobility group, or HMG, box); three frameshift mutations and a splice-acceptor mutation. An identical frameshift mutation is found in two unrelated 46,XY patients, one exhibiting a male phenotype and the other displaying a female phenotype (XY sex reversal). All mutations found affect a single allele, which is consistent with a dominant mode of inheritance. No mutations were found in the SOX9 open reading frame of two patients with chromosome 17q rearrangements, suggesting that the translocations affect SOX9 expression. These findings are consistent with the hypothesis that CD results from haploinsufficiency of SOX9.

Base Sequence↗

Frameshift errors initiated by nucleotide misincorporation.

Studies presented here on the fidelity of DNA synthesis in vitro support the hypothesis that a classical base-substitution intermediate (i.e., a misincorporated nucleotide) can yield a frameshift mutation. By using a fidelity assay specifically designed to detect minus-one-base errors, nucleotide substrate pool imbalances that have previously been shown to increase the rate of misincorporation are now shown to also increase minus-one-base frameshift error rates. Examination of the specificity of the errors produced in reactions with various dNTP pool imbalances and various DNA templates revealed that template nucleotides were preferentially lost when they had as a 5' neighbor a nucleotide complementary to the dNTP provided in excess. This suggests that when a misincorporated nucleotide is complementary to the next nucleotide in the template, a misaligned intermediate containing a correct terminal base pair can form and be extended by a DNA polymerase, leading to a frameshift mutation. We present evidence that the proposed mechanism may operate in vivo and discuss the implications of this model for frameshift mutations induced by DNA damage.

Base Composition↗

Mutational spectrum in the cardioauditory syndrome of Jervell and Lange-Nielsen.

Jervell and Lange-Nielsen syndrome (JLNS) is an autosomal recessive syndrome characterised by profound congenital sensorineural deafness and prolongation of the QT interval on the electrocardiogram, representing abnormal ventricular repolarisation. In a study of ten British and Norwegian families with JLNS, we have identified all of the mutations in the KCNQ1 gene, including two that are novel. Of the nine mutations identified in this group of 10 families, five are nonsense or frameshift mutations. Truncation of the protein proximal to the recently identified C-terminal assembly domain is expected to preclude assembly of KCNQ1 monomers into tetramers and explains the recessive inheritance of JLNS. However, study of a frameshift mutation, with a dominant effect phenotypically, suggests the presence of another assembly domain nearer to the N-terminus.

Amino Acid Substitution↗

Cerebral venous malformations have distinct genetic origin from cerebral cavernous malformations.

BACKGROUND AND PURPOSE: Pathogenesis of cerebral venous malformation (CVM) is unknown. Because of coexistence of CVM and cerebral cavernous malformations (CCM), some studies have suggested that these 2 entities share a common origin and pathogenetic mechanism. METHODS: We have identified and ascertained over 200 families with CCM. Among these, 1 unique family was found to have members affected by both disorders. We have performed mutational analysis in all 3 CCM genes, KRIT1, Malcavernin, and PDCD10, to identify the causative gene in the family. RESULTS: Mutational analysis revealed a frameshift mutation affecting exon 19 of the CCM1 gene (KRIT1) in members with CCM, whereas no such mutation was observed in the member with CVM. CONCLUSIONS: These findings support the hypothesis that CVM and CCM are 2 distinct entities with different pathogenetic mechanisms. This data further supports the hypothesis that CVM has a distinct biology and clinical behavior when compared to CCM. CVM is a benign developmental anomaly and should be managed separately from CCM.

Apoptosis Regulatory Proteins↗

Novel RPGR mutations with distinct retinitis pigmentosa phenotypes in French-Canadian families.

PURPOSE: To characterize the molecular defects in two x-linked retinitis pigmentosa (RP) families. We hypothesized that different RPGR mutations result in distinct RP phenotypes. DESIGN: Observational case series. METHODS: Fifteen members in family I and three members in family II were evaluated. Full ophthalmic evaluations were done. Linkage analyses were performed and likelihood of odds scores (LOD score) were calculated. For mutation analyses, we used dHPLC and automated sequencing. RESULTS: Two novel RPGR mutations were identified in the two families; a Glu 414 (2-bp del) frameshift mutation in family I and an IVS 2-1 (g to a) splice site mutation in family II. All male family members in family I were severely affected by RP but maintained central visual acuities until their 50s and did not develop a bull's eye maculopathy. The female phenotype was highly variable. Some of the carriers exhibited a severe phenotype, one female displayed an asymmetric phenotype, and other carriers were asymptomatic. All members with the RPGR frameshift mutation exhibited rod-cone electroretinograms abnormalities, whereas five members had hearing loss. Male members of family II were severely affected, with early visual acuity loss, central scotomas, and bull's eye maculopathy. The female family members were asymptomatic but displayed cone-rod electroretinograms changes. There was no hearing loss. CONCLUSIONS: Different RPGR mutations lead to distinct RP phenotypes, with a highly variable inter- and intrafamilial phenotypic spectrum of disease that is associated with the type of mutation in RPGR and nonrandom X chromosome inactivation, respectively.

Adolescent↗

A reduced level of charged tRNAArgmnm5UCU triggers the wild-type peptidyl-tRNA to frameshift.

Frameshift mutations can be suppressed by a variety of differently acting external suppressors. The +1 frameshift mutation hisC3072, which has an extra G in a run of Gs, is corrected by the external suppressor mutation sufF44. We have shown that sufF44 and five additional allelic suppressor mutations are located in the gene argU coding for the minor tRNAArgmnm5UCU and alter the secondary and/or tertiary structure of this tRNA. The C61U, G53A, and C32U mutations influence the stability, whereas the C56U, C61U, G53A, and G39A mutations decrease the arginylation of tRNAArgmnm5UCU. The T-10C mutant has a base substitution in the -10 consensus sequence of the argU promoter that reduces threefold the synthesis of tRNAArgmnm5UCU . The lower amount of tRNAArgmnm5UCU or impaired arginylation, either independently or in conjunction, results in inefficient reading of the cognate AGA codon that, in turn, induces frameshifts. According to the sequence of the peptide produced from the suppressed -GGG-GAA-AGA- frameshift site, the frameshifting tRNA in the argU mutants is tRNAGlumnm5s2UUC, which decodes the GAA codon located upstream of the AGA arginine codon, and not the mutated tRNAArgmnm5UCU. We propose that an inefficient decoding of the AGA codon by a defective tRNAArgmnm5UCU stalls the ribosome at the A-site codon allowing the wild-type form of peptidyl-tRNAGlumnm5s2UUC to slip forward 1 nucleotide and thereby re-establish the ribosome in the 0-frame. Similar frame-shifting events could be the main cause of various phenotypes associated with environmental or genetically induced changes in the levels of aminoacylated tRNA.

Alleles↗

Mutation analysis of the methyl-CpG-binding protein 2 gene (MECP2) in Rett patients with preserved speech.

Genomic DNAs from 35 Japanese sporadic patients with Rett syndrome (RTT) were screened for DNA mutations in the entire coding region and exon-intron boundaries of methyl-CpG-binding protein 2 (MECP2). We detected mutations in 30 (85.7%) of 35 patients. Among these 35 RTT patients, five patients (14%) had the preserved speech variant of this disease. Four respective mutations (R133C, R306C, R294X, 2 base pair (bp) deletion) were found in these five patients. Two patients had the same missense mutation, R133C. The patients with the R133C mutation and one with frameshift mutation presented the relatively mild clinical presentation, and the R133C mutation was not found in any other patient without preserved speech. We confirmed that the preserved speech variant is one of the clinical phenotypes of RTT and is also caused by MECP2 mutation. We speculated that the clinical phenotype of patients with the R133C missense mutation might be mild.

Adult↗

Analysis of the p53/BAX pathway in colorectal cancer: low BAX is a negative prognostic factor in patients with resected liver metastases.

PURPOSE: To determine the prognostic value of the central downstream apoptosis effector BAX in relation to its upstream regulator p53 in R0-resected hepatic metastases of colorectal cancer. PATIENTS AND METHODS: Retrospective analysis of 41 patients who underwent potentially curative resection of liver metastases from colarectal cancer was performed. Tumor DNA was screened for p53 mutations by single-stranded conformational polymorphism polymerase chain reaction and for BAX frameshift mutations by fragment length analysis. Protein expression of BAX, p21, and p53 was investigated by immunohistochemistry. RESULTS: Overall median survival was 40.2 months. Tumors with BAX frameshift mutations were considered microsatellite mutator phenotype-positive and were excluded from further prognostic analyses. Patients with high BAX protein expression had a median survival of 53.6 months compared with 35.4 months for patients with low BAX expression (P < .05). The negative prognostic value of low BAX expression was more evident in those patients with wild-type p53 (median survival, 54.0 v 23.3 months for BAX-negative tumors; P < .01). Low BAX expression was an independent negative prognostic marker in multivariate regression analysis for all patients independent of the p53 status (relative risk, 3.03, P = .03), especially for p53 wild-type tumors (relative risk, 8.21; P = .0095). CONCLUSION: We conclude that low BAX expression is an independent negative prognostic marker in patients with hepatic metastases of colorectal cancer. The best survival was seen in patients with an intact p53-to-BAX pathway; ie, wild-type p53- and BAX-positive tumors. Thus, analysis of apoptosis signaling pathways (here, p53 in concert with its downstream death effector, BAX) might yield more prognostic power in future studies as compared with analysis of single genes such as p53 alone.

Adult↗

In vitro evidence that UV-induced frameshift and substitution mutations at T tracts are the result of misalignment-mediated replication past a specific thymine dimer.

A previous study of UV-induced (254 nm) mutations in the lacI gene of Escherichia coli found that frameshift mutations accounted for about 35% of the observed mutations and that these mutations occurred predominantly at An.Tn sequences [Miller, J.H. (1985) J. Mol. Biol. 182, 48-65]. Because An.Tn sequences are hotspots for cis-syn thymine dimer formation [Brash, D.E., & Haseltine, W. A. (1982) Nature 298, 189-192], it would appear that UV-induced frameshift mutations are the result of an error during replicative bypass of a thymine dimer within such a sequence. To test the validity of such a proposal, replication experiments were carried out on templates containing cis-syn thymine dimers at each of the five possible sites of a T6 tract. The 59-mer templates were prepared by ligating oligonucleotides containing an EcoRI site to the 5'-end of decamers containing the cis-syn thymine dimer and oligonucleotides containing the primer site to the 3'-end. Primer-extension reactions were then carried out on these templates with a 3'----5' exonuclease-deficient (exo-) Klenow fragment of E. coli polymerase I and an exo-T7 polymerase (Sequenase Version 2.0). The replicative bypass products were cleaved with EcoRI to rigorously establish and quantify the presence of frameshift mutations. Both polymerases were able to bypass dimers at all sites, but only the exo-T7 polymerase led to detectable frameshifts, both -1 (approximately 30%) and -2 (approximately 5%), and only with the template containing a cyclobutane dimer at the second site from the 5'-end of the T6 tract. Sequencing of the T7 polymerase-catalyzed bypass products of all templates demonstrated that within the limits of discrimination only As were introduced opposite the dimer-containing T tracts. The only exception was for the template with the dimer at the second site which led to a readily detectable amount of a substitution mutation (approximately 30%) opposite the 5'-thymine of the T6 tract. A mechanism involving a competition between reversible misalignment and realignment steps and irreversible elongation steps is proposed to explain the origin of both the frameshift and the substitution mutations. The implications of this work to the mechanism of UV-induced frameshift and substitution mutations at T tracts in vivo are discussed.

Autoradiography↗

Spectrum of molecular alterations in colorectal, upper urinary tract, endocervical, and renal carcinomas arising in a patient with hereditary non-polyposis colorectal cancer.

Hereditary nonpolyposis colon cancer (HNPCC) syndrome is the most frequent hereditary cancer syndrome predisposing to cancers of various locations, especially colon, endometrium, stomach, and upper urinary tract. Carcinomas of the kidney parenchyma are not considered as an HNPCC-related tumor. HNPCC tumors are characterized by microsatellite instability (MSI) due to a defect in mismatch repair (MMR) and carry somatic frameshift mutations in mononucleotide repeats within the coding regions of key genes. We report the first case of a papillary carcinoma of the kidney in an HNPCC patient who developed carcinomas of the upper urinary tract, endocervix, and colon. Whereas the HNPCC-related tumors demonstrated MSI phenotype, loss of MSH2 protein expression, and frameshift mutations in several of the 13 target genes analyzed, the kidney cancer displayed MSS phenotype, normal MMR protein expression, and no frameshift mutation in target genes. Our observations do not support the possibility that papillary carcinomas are part of HNPCC syndrome.

Colorectal Neoplasms↗