Juvenile polyposis syndrome (JPS) is characterized by predisposition to hamartomatous polyps in the gastrointestinal (GI) tract, specifically in the stomach, small intestine, colon, and rectum. The term "juvenile" refers to the type of polyp rather than to the age of onset of polyps. Most individuals with JPS have some polyps by age 20 years; some may have only four or five polyps over their lifetime, whereas others in the same family may have more than 100. If the polyps are left untreated, they may cause bleeding and anemia. Most juvenile polyps are benign; however, malignant transformation can occur. Risk for GI cancers ranges from 11% to 86%. Most of this increased risk is attributed to colon cancer, but cancers of the stomach, upper GI tract, and pancreas have also been reported. A combined syndrome of JPS and hereditary hemorrhagic telangiectasia (HHT) is present in most individuals with an SMAD4 pathogenic variant.

Lynch syndrome is characterized by an increased risk for colorectal cancer (CRC) and cancers of the endometrium, ovary, stomach, small bowel, urinary tract, biliary tract, brain (usually glioblastoma), skin (sebaceous adenomas, sebaceous carcinomas, and keratoacanthomas), pancreas, and prostate. Cancer risks and age of onset vary depending on the associated gene. Several other cancer types have been reported to occur in individuals with Lynch syndrome (e.g., breast, sarcomas, adrenocortical carcinoma). However, the data are not sufficient to demonstrate that the risk of developing these cancers is increased in individuals with Lynch syndrome.

Lynch syndrome is characterized by an increased risk for colorectal cancer (CRC) and cancers of the endometrium, ovary, stomach, small bowel, urinary tract, biliary tract, brain (usually glioblastoma), skin (sebaceous adenomas, sebaceous carcinomas, and keratoacanthomas), pancreas, and prostate. Cancer risks and age of onset vary depending on the associated gene. Several other cancer types have been reported to occur in individuals with Lynch syndrome (e.g., breast, sarcomas, adrenocortical carcinoma). However, the data are not sufficient to demonstrate that the risk of developing these cancers is increased in individuals with Lynch syndrome.

Li-Fraumeni syndrome (LFS) is a cancer predisposition syndrome associated with high risks for a diverse spectrum of childhood- and adult-onset malignancies. The lifetime risk of cancer in individuals with LFS is =70% for men and =90% for women. Five cancer types account for the majority of LFS tumors: adrenocortical carcinomas, breast cancer, central nervous system tumors, osteosarcomas, and soft-tissue sarcomas. LFS is associated with an increased risk of several additional cancers including leukemia, lymphoma, gastrointestinal cancers, cancers of head and neck, kidney, larynx, lung, skin (e.g., melanoma), ovary, pancreas, prostate, testis, and thyroid. Individuals with LFS are at increased risk for cancer in childhood and young adulthood; survivors are at increased risk for multiple primary cancers.

Oligodontia-cancer predisposition syndrome is a rare, genetic, odontologic disease characterized by congenital absence of six or more permanent teeth (excluding the third molars) in association with an increased risk for malignancies, ranging from gastrointestinal polyposis to early-onset colorectal cancer and/or breast cancer. Ectodermal dysplasia (manifesting with sparse hair and/or eyebrows) may also be associated.

APC-associated polyposis conditions include (classic or attenuated) familial adenomatous polyposis (FAP) and gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS). FAP is a colorectal cancer (CRC) predisposition syndrome that can manifest in either classic or attenuated form. Classic FAP is characterized by hundreds to thousands of adenomatous colonic polyps, beginning on average at age 16 years (range 7-36 years). For those with the classic form of FAP, 95% of individuals have polyps by age 35 years; CRC is inevitable without colectomy. The mean age of CRC diagnosis in untreated individuals is 39 years (range 34-43 years). The attenuated form is characterized by multiple colonic polyps (average of 30), more proximally located polyps, and a diagnosis of CRC at a later age than in classic FAP. For those with an attenuated form, there is a 70% lifetime risk of CRC and the mean age of diagnosis is 50-55 years. Extracolonic manifestations are variably present and include polyps of the stomach and duodenum, osteomas, dental abnormalities, congenital hypertrophy of the retinal pigment epithelium (CHRPE), benign cutaneous lesions, desmoid tumors, adrenal masses, and other associated cancers. GAPPS is characterized by proximal gastric polyposis, increased risk of gastric adenocarcinoma, and no duodenal or colonic involvement in most individuals reported.

Hereditary mixed polyposis syndrome-2 (HMPS2) is characterized by colonic polyps of mixed hyperplastic, adenomatous, and occasional juvenile types. Polyposis eventually progresses to colorectal cancer (Cao et al., 2006). For a discussion of genetic heterogeneity of HMPS, see HMPS1 (601228).

Diamond-Blackfan anemia (DBA) is characterized by a profound normochromic and usually macrocytic anemia with normal leukocytes and platelets, congenital malformations in up to 50%, and growth deficiency in 30% of affected individuals. The hematologic complications occur in 90% of affected individuals during the first year of life. The phenotypic spectrum ranges from a mild form (e.g., mild anemia or no anemia with only subtle erythroid abnormalities, physical malformations without anemia) to a severe form of fetal anemia resulting in nonimmune hydrops fetalis. DBA is associated with an increased risk for acute myelogenous leukemia (AML), myelodysplastic syndrome (MDS), and solid tumors including osteogenic sarcoma.

Any colorectal cancer in which the cause of the disease is a mutation in the SMAD7 gene.

APC-associated polyposis conditions include (classic or attenuated) familial adenomatous polyposis (FAP) and gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS). FAP is a colorectal cancer (CRC) predisposition syndrome that can manifest in either classic or attenuated form. Classic FAP is characterized by hundreds to thousands of adenomatous colonic polyps, beginning on average at age 16 years (range 7-36 years). For those with the classic form of FAP, 95% of individuals have polyps by age 35 years; CRC is inevitable without colectomy. The mean age of CRC diagnosis in untreated individuals is 39 years (range 34-43 years). The attenuated form is characterized by multiple colonic polyps (average of 30), more proximally located polyps, and a diagnosis of CRC at a later age than in classic FAP. For those with an attenuated form, there is a 70% lifetime risk of CRC and the mean age of diagnosis is 50-55 years. Extracolonic manifestations are variably present and include polyps of the stomach and duodenum, osteomas, dental abnormalities, congenital hypertrophy of the retinal pigment epithelium (CHRPE), benign cutaneous lesions, desmoid tumors, adrenal masses, and other associated cancers. GAPPS is characterized by proximal gastric polyposis, increased risk of gastric adenocarcinoma, and no duodenal or colonic involvement in most individuals reported.

Lynch syndrome is characterized by an increased risk for colorectal cancer (CRC) and cancers of the endometrium, ovary, stomach, small bowel, urinary tract, biliary tract, brain (usually glioblastoma), skin (sebaceous adenomas, sebaceous carcinomas, and keratoacanthomas), pancreas, and prostate. Cancer risks and age of onset vary depending on the associated gene. Several other cancer types have been reported to occur in individuals with Lynch syndrome (e.g., breast, sarcomas, adrenocortical carcinoma). However, the data are not sufficient to demonstrate that the risk of developing these cancers is increased in individuals with Lynch syndrome.

Lynch syndrome is characterized by an increased risk for colorectal cancer (CRC) and cancers of the endometrium, ovary, stomach, small bowel, urinary tract, biliary tract, brain (usually glioblastoma), skin (sebaceous adenomas, sebaceous carcinomas, and keratoacanthomas), pancreas, and prostate. Cancer risks and age of onset vary depending on the associated gene. Several other cancer types have been reported to occur in individuals with Lynch syndrome (e.g., breast, sarcomas, adrenocortical carcinoma). However, the data are not sufficient to demonstrate that the risk of developing these cancers is increased in individuals with Lynch syndrome.

MUTYH polyposis (also referred to as MUTYH-associated polyposis, or MAP) is characterized by a greatly increased lifetime risk of colorectal cancer (CRC). Although typically associated with ten to a few hundred colonic adenomatous polyps, CRC develops in some individuals in the absence of polyposis. Serrated adenomas, hyperplastic/sessile serrated polyps, and mixed (hyperplastic and adenomatous) polyps can also occur. Duodenal adenomas are common, with an increased risk of duodenal cancer. The risk for malignancies of the ovary and bladder is also increased, and there is some evidence of an increased risk for breast and endometrial cancer. Additional reported features include thyroid nodules, benign adrenal lesions, jawbone cysts, and congenital hypertrophy of the retinal pigment epithelium.

NTHL1 tumor syndrome is characterized by an increased lifetime risk for colorectal cancer (CRC), breast cancer, and colorectal polyposis. Colorectal polyps can be adenomatous, hyperplastic, and/or sessile serrated. Duodenal polyposis has also been reported. Additional cancers reported in individuals with NTHL1 tumor syndrome include endometrial cancer, cervical cancer, urothelial carcinoma of the bladder, meningiomas, unspecified brain tumors, basal cell carcinomas, head and neck squamous cell carcinomas, and hematologic malignancies. The cumulative lifetime risk of developing extracolonic cancer by age 60 years has been estimated at 35% to 78%.

Periodontal Ehlers-Danlos syndrome (pEDS) is characterized by distinct oral manifestations. Periodontal tissue breakdown beginning in the teens results in premature loss of teeth. Lack of attached gingiva and thin and fragile gums lead to gingival recession. Connective tissue abnormalities of pEDS typically include easy bruising, pretibial plaques, distal joint hypermobility, hoarse voice, and less commonly manifestations such as organ or vessel rupture. Since the first descriptions of pEDS in the 1970s, 148 individuals have been reported in the literature; however, future in-depth descriptions of non-oral manifestations in newly diagnosed individuals with a molecularly confirmed diagnosis of pEDS will be important to further define the clinical features.

Mismatch repair cancer syndrome-2 (MMRCS2) is an autosomal recessive childhood cancer predisposition syndrome characterized by hematologic malignancy, brain tumors, and gastrointestinal tumors. Multiple cafe-au-lait spots reminiscent of neurofibromatosis type I (NF1; 162200) may be present. Microsatellite instability may be detected in tumor samples (Muller et al., 2006). For a discussion of genetic heterogeneity of mismatch repair cancer syndrome (MMRCS), see MMRCS1 (276300).

Mismatch repair cancer syndrome-3 (MMRCS3) is an autosomal recessive childhood cancer predisposition syndrome characterized by brain tumors, hematologic malignancy, and gastrointestinal tumors. Multiple cafe-au-lait spots, axillary freckling, and, rarely, Lisch nodules reminiscent of neurofibromatosis type I (NF1; 162200) may be present (Hegde et al., 2005, Ostergaard et al., 2005). Microsatellite instability may be detected in tumor samples (Hegde et al., 2005). For a discussion of genetic heterogeneity of mismatch repair cancer syndrome, see MMRCS1 (276300).

Mismatch repair cancer syndrome-4 (MMRCS4) is an autosomal recessive childhood cancer predisposition syndrome characterized by early-onset leukemia/lymphoma, brain tumors, colorectal/gastrointestinal cancers, and other rare malignancies, including rhabdomyosarcoma (summary by Li et al., 2015). Cafe-au-lait spots are usually present (De Vos et al., 2006). For a discussion of genetic heterogeneity of mismatch repair cancer syndrome, see MMRCS1 (276300).

Tumor predisposition syndrome-2 (TPDS2) is an autosomal recessive cancer predisposition syndrome characterized by the onset of various types of tumors or malignancies in young adulthood. The most common clinical manifestations include acute myeloid leukemia (AML), myelodysplastic syndrome, colorectal adenomatous polyposis and carcinoma, and uveal melanoma, although other tumors and malignancies have been reported (summary by Palles et al., 2022). For a discussion of genetic heterogeneity of TPDS, see TPDS1 (614327).

Any Birt-Hogg-Dube (BHD) syndrome in which the cause of the disease is a variation in the FLCN gene.