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Broad phenotypic spectrum in familial adenomatous polyposis; from early onset and severe phenotypes to late onset of attenuated polyposis with the first manifestation at age 72
BMC Medical Genetics volume 9, Article number: 101 (2008)
Familial adenomatous polyposis (FAP) is typically characterized by multiple colonic polyps and frequent extracolonic features. Whereas the number of colonic polyps has been linked to the APC gene mutation, possible genotype-phenotype correlations largely remain to be defined for the extracolonic manifestations.
Full genomic sequencing combined with multiplex ligation-dependent probe amplification was used to identify APC gene mutations, which were correlated to the clinical presentations.
10 novel APC gene mutations were identified in 11 families. A broad spectrum of extracolonic manifestations was identified in most of these individuals. Two sisters with an insertion in codon 528 (c.1582_1583insGC) both showed severe phenotypes with classical polyposis, upper gastrointestinal polyps and thyroid cancer. A woman with a 3'APC mutation (c.5030_5031insAA) developed colon cancer at age 72 as the first manifestation of attenuated FAP.
With an increasing number of FAP families diagnosed, a broad and variable tumor spectrum and a high frequency of extracolonic manifestations are gradually recognized. We report novel APC mutations and present two FAP cases that suggest familial aggregation of thyroid cancer and demonstrate the need to consider attenuated FAP also among elderly patients with colon cancer.
Familial adenomatous polyposis (FAP) affects about 1/13–18000 individuals, is characterized by development of multiple colonic polyps and causes less than 1% of colorectal cancer [1, 2]. APC encodes for a 2843 amino acid protein that contains a variety of functional domains involved in transcription, cell cycle control, migration, differentiation, and apoptosis. Mutations in APC were demonstrated in 1991 and to date some 800 mutations have been identified [3, 4]. Frameshift mutations predominate and nonsense mutations are found in one third of the cases, whereas large deletions and missense mutations represent rare causes of FAP . A mutation cluster region in the 5'end of exon 15 of the APC gene has been identified and the two most frequent mutations, which account for 11–17% of the germline alterations, affect codons 1061 and 1309 .
The severity of colonic polyposis has been linked to the genotype. Mutations between APC codons 1250 and 1464 cause profuse polyposis, generally with > 5000 polyps, and the recurrent codon 1309 mutation is associated with early onset and development of thousands of polyps [6, 7]. The classical or intermediate phenotype is associated with mutations between codons 157 (in exon 4) and 1595 (in exon 15), whereas mutations before codon 157, in the alternatively spliced region of exon 9, and after codon 1595 cause attenuated FAP (AFAP) [8, 9].
Extracolonic manifestations are estimated to develop in 70% of FAP patients . Except for an association between mutations in codons 311–1444 and congenital hypertrophy of the retinal pigment epithelium (CHRPE), extracolonic manifestations have been described in conjunction with mutations throughout the APC gene [6, 7, 10]. We present new APC mutations and specifically discuss two cases that demonstrate the broad phenotypic spectrum in FAP; two sisters who concordantly developed classical polyposis, upper gastrointestinal polyps, and thyroid cancer and a woman with a 3'APC mutation who presented with the first symptom of FAP at age 72.
All patients underwent genetic counseling and APC mutation testing because of clinical suspicion of FAP. The study complied with Ethics guidelines and the samples were obtained as part of a clinical routine analysis with informed consent. Totally, 15 individuals with clinical FAP manifestations were subjected to mutation analysis, which applied DNA sequencing of exons 1–14 and the protein truncation test (PTT) to screen for truncating mutations in exon 15 [for details see ]. Analysis for large deletions was performed using the multiplex ligation-dependent probe amplification (MLPA) assay in cases where sequencing did not identify any mutation [for details see ].
Totally, 15 individuals with clinical FAP were subjected to mutation analysis and APC gene mutations were identified in 11 individuals/families, whereas no mutation could be identified in 4 individuals. Clinical characteristics of the cases in which APC gene mutations were identified are summarized in table 1. The mutations included 4 small insertions/deletions, 3 nonsense mutations, 2 splice site mutations, and 2 whole-gene deletions (detected by MLPA in cases A37 and A40). 5 individuals reported no family history of polyposis/colorectal cancer. Among patients with FAP-predisposing APC gene mutations, colonic adenomas were diagnosed at surveillance or because of symptoms at mean 32 (14–72) years of age. Two individuals were diagnosed with colonic polyposis and synchronous colon cancer at ages 45 and 72, respectively. Duodenal polyps were diagnosed in 9 individuals at mean 40 (24–73) years of age and gastric polyps developed in 7 individuals at mean 40 (26–73) years of age. Desmoid tumors of the abdominal wall and the retroperitoneum developed in two patients at ages 20 and 73 and were associated with mutations in exon 15.
Phenotypic similarity was demonstrated in two sisters (A46-1 and A46-2) with an insertion (c.1582_1583insGC) in an area of the APC gene associated with intermediate polyposis. They had a family history of FAP with a mother diagnosed with colonic and duodenal polyposis who later developed a duodenal carcinoma from which she died. Both sisters developed colon polyposis with the first adenomas diagnosed at ages 13 and 18. At ages 18 and 28, respectively, they were diagnosed with papillary thyroid cancer and underwent radical surgery. Upper gastrointestinal manifestations later developed with duodenal polyps diagnosed at ages 27 and 28 and gastric polyps at ages 27 and 40.
Attenuated FAP was demonstrated in a woman without family history of colorectal polyps or cancer. She developed synchronous colon cancers at age 72. One year later, at age 73, she was diagnosed with duodenal and gastric polyps and a desmoid tumor of the abdominal wall. The synchronous colon cancers did not lead to clinical suspicion of FAP, but the development of extracolonic features linked to FAP prompted APC mutation analysis, which identified an insertion (c.5030_5031insAA) in the 3'end of the gene.
Of the 10 previously unpublished mutations here reported, 9 were located in the part of the APC gene associated with classical FAP (table 1) [5, 15]. New mutations are estimated to cause 20–25% of FAP and 5 cases here identified, including two individuals with whole-gene APC deletions, most likely represent new mutations [14, 15]. The expression of colonic polyposis, i.e. profuse, classical and attenuated forms with variable ages at onset, has in several studies been linked to the genotype, whereas genotype-phenotype correlations for the extracolonic features remain to define. Upper gastrointestinal tumors include duodenal adenomas, which develop in 50–90% of individuals, fundic gland polyps in 40–50%, and adenomas in the gastric antrum found in 5–20%. In our series, all but one of the patients developed extracolonic features and an increased risk has been described for patients with mutations in exon 4, in codons 564–1465, and in the 3'end of APC [6, 7, 10]. Desmoid tumors develop in 10–15% of FAP patients and have been associated with mutations distal to codon 1444, a family history of desmoids and previous surgical trauma . The two cases with desmoids here identified support this link with mutations located in codons 1450 and 1784. Several other factors, e.g. prior abdominal surgery and modifying genes, may however influence the risk. Identification of such risk-predisposing factors would be clinically valuable in order to determine the risk of desmoids tumor development after prophylactic surgery.
Extraintestinal malignancies, i.e. thyroid cancer, hepatoblastoma, and brain tumors, develop only in a few percent of FAP patients. Female FAP patients are at about 100 times increased risk of thyroid cancer, which typically develop at age 30 [17, 18]. Two sisters in our series developed papillary thyroid cancer at ages 19 and 28, respectively. Although rare, thyroid cancer in first-degree relatives has been reported in a small number of families [19–21]. A link between thyroid cancer and mutations in the 5'part of exon 15 (codons 1286 and 1513) has been suggested . Unfortunately, mutation data lack in most of the other familial cases reported, but two families with affected first-degree relatives and mutations 5' to codon 1513 have been reported. Our finding of thyroid cancer in two sisters with the insertion c.1582_1583insGC pushes the thyroid cancer associated region of APC further 3', but until the genetic factors that cause thyroid cancer in FAP have been delineated, caution is warranted for at-risk females in families where thyroid cancer has been diagnosed.
AFAP with development of less than 100 colonic polyps and a higher age at onset is estimated to represent 10% of the cases . The first symptom, i.e. development of colon cancer at age 72 in an individual with a mutation in codon 1784, i.e. within the 3' part of exon 15, reflects the high risk of colon cancer despite a low number of polyps in AFAP [9, 23, 24]. This woman also developed a desmoid tumor and an osteoma at age 73 and an adenocarcinoma of the small intestine at age 74. Mutations beyond codon 1600 are rare, but may be underestimated with currently used mutation detection techniques. This case thus serves as a reminder of the need to consider FAP in patients who develop synchronous colorectal cancers and extracolonic features also at older age.
Bjork J, Akerbrant H, Iselius L, Alm T, Hultcrantz R: Epidemiology of familial adenomatous polyposis in Sweden: changes over time and differences in phenotype between males and females. Scand J Gastroenterol. 1999, 34: 1230-5. 10.1080/003655299750024751.
Bulow S, Faurschou Nielsen T, Bulow C, Bisgaard ML, Karlsen L, Moesgaard F: The incidence rate of familial adenomatous polyposis. Results from the Danish Polyposis Register. Int J Colorectal Dis. 1996, 11: 88-91. 10.1007/BF00342466.
Kinzler KW, Nilbert MC, Su L-K, Vogelstein B, Bryan TM, Levy DB, Smith KJ, Preisinger AC, Hedge P, McKechnie D, Finniear R, Markham A, Groffen J, Bogudski MS, Altschui SF, Horii A, Ando H, Miyoshi Y, Miki Y, Nishisho I, Nakamura Y: Identification of FAP locus genes from chromosome 5q21. Science. 1991, 253: 661-665. 10.1126/science.1651562.
Goss KH, Groden J: Biology of the adnomatous polyposis coli tumor suppressor. J Clin Oncol. 2000, 18: 1967-79.
Beroud C, Soussi T: APC gene: Database of germline and somatic mutations in human tumors and cell lines. Nucl Acid Res. 1996, 24: 121-4. 10.1093/nar/24.1.121.
Ficari F, Cama A, Valanzano R, Curia MC, Palmirotta R, Aceto G, Esposito DL, Crognale S, Lombardi A, Messerini L, Mariana-Costantini R, Tonelli F, Battista P: APC gene mutations and colorectal adenomatosis in familial adenomatous polyposis. Br J Cancer. 2000, 82: 348-53. 10.1054/bjoc.1999.0925.
Nieuwenhuis MH, Vasen HFA: Correlations between mutation site in APC and phenotype of familial adenomatous polyposis (FAP): A review of the literature. Crit Rev Onc Hematol. 2007, 61: 153-61. 10.1016/j.critrevonc.2006.07.004.
Spirio L, Olschwang S, Groden J, Robertson M, Samowitz W, Joslyn G, Gelbert L, Thliveris A, Carlson M, Otterud B, Lynch H, Watson P, Lynch P, Lurent-Puig P, Burt R, Hughes JP, Thomas G, Leppert M, White R: Alleles of the APC gene: an attenuated form of familial polyposis. Cell. 1993, 75: 951-7. 10.1016/0092-8674(93)90538-2.
Soravia C, Berk T, Madlensky L, Mitri A, Cheng H, Gallinger S, Cohen Z, Bapat B: Genotype-phenotype correlations in attenuated adenomatous polyposis coli. Am J Hum Genet. 1998, 62: 1290-301. 10.1086/301883.
Enomoto M, Konishi M, Iwama T, Utsunomiya J, Sugihara KI, Miyaku M: The relationship between frequencies of extracolonic manifestations and the position of the APC germline mutation in patients with familial adenomatous polyposis. Jpn J Clin Oncol. 2000, 30: 82-8. 10.1093/jjco/hyd017.
Nilbert M, Fernebro J, Kristoffersson U: Novel germline APC mutations in Swedish patients with familial adenomatous polyposis and Gardner syndrome. Scand J Gastroenterol. 2000, 35: 1200-3. 10.1080/003655200750056691.
Mueller J, Kanter-Smoler G, Nygren AO, Errami A, Grönberg H, Holmberg E, Björk J, Wahlström J, Nordling M: Identification of genomic deletions in the APC gene in familial adenomatous polyposis by two independent quantitative techniques. Genet Test. 2004, 8: 248-56. 10.1089/gte.2004.8.248.
Kanter-Smoler G, Fritzell K, Rohlin A, Engwall Y, Hallbeg B, Bergman A, Meuller J, Gronberg H, Karlsson P, Björk J, Nordling M: Clinical characterization and the mutation spectrum in Swedish adenomatous polyposis families. BMC Med. 2008, 6: 10-10.1186/1741-7015-6-10.
Bisgaard ML, Fenger K, Bülow S, Niebuhr E, Mohr J: Familal adenomatous polyposis (FAP): frequency, penetrance, and mutation rate. Hum Mutat. 1994, 3: 121-5. 10.1002/humu.1380030206.
Sieber OM, Lamlum H, Crabtree MD, Rowan AJ, Rowan AJ, Barclay E, Lipton L, Hodgson S, Thomas HJ, Neale K, Phillips RK, Farrington SM, Dunlop MG, Mueller HJ, Bisgaard ML, Bulow S, Fidalgo P, Albuquerque C, Scarano MI, Bodmer W, Tomlinson IP, Heinimann K: Whole-gene APC deletions cause classical familial adenomatous polyposis, but not attenuated polyposis or "multiple" colorectal adenomas. PNAS. 2002, 99: 2954-8. 10.1073/pnas.042699199.
Sturt NJH, Gallagher MC, Bassett P, Philp CR, Neale KF, Tomlinson IP, Silver AR, Phillips RK: Evidence for genetic predisposition to desmoids tumors in familial adenomatous polyposis independent of the germline APC mutation. Gut. 2004, 53: 1832-6. 10.1136/gut.2004.042705.
Bülow S, Holm NV, Mellemgaard A: Papillary thyroid carcinoma in Danish patients with familial adenomatous polyposis. Int J Colorectal Cancer Dis. 1988, 3: 29-31. 10.1007/BF01649679.
Truta B, Allen BA, Conrad PG, Weinberg V, Miller GA, Pomponio R, Lipton LR, Guerra G, Tomlinson IP, Sleisenger MH, Kim YS, Terdima JP: Genotype and phenotype of patients with both familial adenomatous polyposis and thyroid carcinoma. Fam Cancer. 2003, 2: 95-9. 10.1023/A:1025762706854.
Brozek I, Plawski A, Podralska M, Kanka C, Slomski R, Limon J: Thyroid cancer in two siblings with FAP syndrome and APC mutation. Int J Colorectal Dis. 2008, 23: 331-2. 10.1007/s00384-007-0365-0.
Kameyama K, Takami H: FAP associated thyroid carcinoma in mother and her daughter. Fam Cancer. 2001, 1: 83-6. 10.1023/A:1013848307459.
Lee S, Hong SW, Shin SJ, Kim YM, Rhee Y, Jeon BI, Moon WC, Oh MR, Lim SK: Papillary thyroid carcinoma associated with familial adenomatous polyposis: molecular analysis of pathogenesis in a family and review of the literature. Endocrin J. 2004, 51: 317-23. 10.1507/endocrj.51.317.
Lyster Knudsen A, Bisgaard ML, Bulow S: Attenuated familial adenomatous polyposis (AFAP). Review of the literature. Fam Cancer. 2003, 2: 43-55. 10.1023/A:1023286520725.
Burt RW, Leppert MF, Slattery ML, Samowitz WS, Spirio LN, Kerber RA, Kuwada SK, Neklason DW, Disario JA, Lyon E, Hughes JP, Chey WY, Whute RL: Genetic testing and phenotype in a large kindred with attenuated familial polyposis. Gastroenterology. 2004, 127: 444-51. 10.1053/j.gastro.2004.05.003.
Luijt Van der RB, Meera Khan P, Vasen HFA, Breukel C, Tops CM, Scott RJ, Fodde R: Germline mutations in the 3' part of APC exon 15 do not result in truncated proteins and are associated withe attenuated adenomatous polyposis coli. Hum Genet. 1996, 98: 727-34. 10.1007/s004390050293.
Young J, Simms LA, Tarish J, Buttenshaw R, Knight N, Anderson GJ, Bell A, Leggett B: A family with attenuated familial adenomatous polyposis due to a mutation in the alternatively spliced region of APC exon 9. Hum Mut. 1998, 11: 450-5. 10.1002/(SICI)1098-1004(1998)11:6<450::AID-HUMU5>3.0.CO;2-P.
The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2350/9/101/prepub
This study was supported by grants from the Swedish Cancer Fund and the Swedish Research Council.
The authors declare that they have no competing interests.
MN evaluated the genetic analyses, collected clinical data and wrote the article. UK performed genetic counseling and was responsible for family data. ME, OJ and PM were responsible for clinical data and identified relevant patients for genetic testing. ER performed the APC sequencing analyses. All authors read and approved the final manuscript.
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Nilbert, M., Kristoffersson, U., Ericsson, M. et al. Broad phenotypic spectrum in familial adenomatous polyposis; from early onset and severe phenotypes to late onset of attenuated polyposis with the first manifestation at age 72. BMC Med Genet 9, 101 (2008). https://doi.org/10.1186/1471-2350-9-101
- Thyroid Cancer
- Familial Adenomatous Polyposis
- Papillary Thyroid Cancer
- Desmoid Tumor
- Familial Adenomatous Polyposis Patient