Synopsis Gastric Cancer (GC) is 3rd leading cause of cancer related death worldwide; only 28.3% of are expected to survive >5 years. Although GC incidence has declined in the US during the last decade, an increase in the incidence of GC has been estimated for 2016. GC risk factors include, male gender, having >60 years, infectious agents such as H. pylori, GC family history, certain occupations, tobacco use, and diet, among others. Prognosis of GC is largely dependent on the tumor stage at diagnosis and classification as intestinal or diffuse type, which has worse prognosis. Although promising chemoprevention agents have been reported to decrease GC risk, none have been implemented into clinical practice to date. Risk assessment and surveillance guidelines have been implemented in Asian countries with high incidence of GC, whereas in the US, only the American Society for Gastrointestinal Endoscopy has recently published guidelines for the screening and management gastric lesions. Importance of diagnosis of GC at an early stage is imperative since 5 year survival rates can approximate 90% in this setting.

In Puerto Rico, colorectal cancer (CRC) represents the second leading cause of cancer in men and women. Familial CRC accounts for 10–15% of the total CRC cases, while Lynch syndrome accounts for approximately 2–4% of cases. Limited information is available about the prevalence, clinical manifestations, and genetic mutations of hereditary CRC in US Hispanic individuals. In this paper we report a novel mutation in the hMLH1 gene in a Puerto Rican Hispanic family with Lynch syndrome recruited through the Puerto Rico Familial Colorectal Cancer Registry (PURIFICAR). Our proband was identified by applying Amsterdam and Bethesda criteria for Lynch syndrome, analysis of protein expression by immunohistochemistry, and genetic sequencing of the mismatch repair genes. A novel mutation at c.2044_2045 in hMLH1 consisting of the deletion of two consecutive nucleotides (AT) at exon 18 was identified. This deletion causes a frameshift in the protein coding sequence at p.682 resulting in premature termination and a truncated MLH1 protein. To our knowledge, this mutation has not been previously reported in the literature. The detection of this novel mutation in MLH1 further emphasizes the need for genetic testing in at-risk patients for hereditary CRC from various ethnic and racial backgrounds.

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