Page 97 - Genomic Medicine in Emerging Economies

86 CHAPTER 5: Screening for Hereditary Cancer in Latin America

that is, the Amsterdam II criteria were fulfilled by 64% of path_MMR carriers,
although MSI, IHC, and family history are still the primary criteria in sev-
eral countries, where no genetic testing for Lynch syndrome is available yet
(Rossi et al., 2017). However, awareness of hereditary cancer among clini-
cians involved in the diagnosis and treatment of colorectal cancer is currently
low, but families actually meeting the clinical criteria may not have been
identified (Sjursen et al., 2016). In addition, the average life expectancy in
Latin America and the Caribbean is 75 years and inequalities persist among
and within the countries (www.paho.org). These countries are mainly repre-
sented by a young population where family history could be less informative
and not sensitive to assessing genetic screening for Lynch syndrome (Rossi
et al., 2017).

In summary, the Latin American Lynch syndrome mutation spectrum includes
multiple new mutations, international founder effects, genetically frequent
regions, and potential founder mutations, which will be useful for future the
development of genetic testing.

Latin American Collaborative Network
In Latin America, the application of genetic tests to patients as part of clini-
cal practice is a big challenge because of low budgets in public health. In this
sense, international collaborations would be helpful for the development of
additional studies on Lynch syndrome in Latin American countries to both,
increase the knowledge of MMR variants in different populations and to bring
additional awareness of this condition to medical professionals and public
health leaders in Latin America.

FAMILIAL ADENOMATOUS POLYPOSIS

Clinical and Genetic Features
Familial adenomatous polyposis (FAP, OMIM No. 175100) is an autosomal
dominant disease with complete penetrance, which account for about 1% of
colorectal cancers. Clinical manifestations include the development of hun-
dreds to thousands of adenomatous polyps located mainly in the colon and
rectum, and the development of colorectal cancer at 35–40 years of age (Strate
and Syngal, 2005). Consequently, the recommended treatment for FAP patients
is prophylactic colectomy in young adulthood. Moreover, individuals with
FAP can present a number of benign extracolonic features, including multiple
osteomas, epidermoid cysts, desmoid tumors, and congenital hypertrophy of
the retinal pigment epithelium. According to the polyp number, the pheno-
type can be classified as classical (more than 100 polyps) or attenuated (fewer
than 100 polyps) (Knudsen et al., 2003), this classification is very important in
order to select families for genetic studies.