Ethnicity-Based Variations in Focal Adhesion Kinase Signaling in Glioblastoma Gene Expression: A Study of the Puerto Rican Hispanic Population.

Glioblastoma (GBM), an aggressive form of brain cancer, has a higher incidence in non-Hispanics when compared to the US Hispanic population. Using data from RT-PCR analysis of 21 GBM tissue from Hispanic patients in Puerto Rico, we identified significant correlations in the gene expression of focal adhesion kinase and proline-rich tyrosine kinase (PTK2 and PTK2B) with NGFR (nerve growth factor receptor), PDGFRB (platelet-derived growth factor receptor B), EGFR (epithelial growth factor receptor), and CXCR1 (C-X-C motif chemokine receptor 1). This study further explores these correlations found in gene expression while accounting for sex and ethnicity. Statistically significant (p < 0.05) correlations with an r value > ±0.7 were subsequently contrasted with mRNA expression data acquired from cBioPortal for 323 GBM specimens. Significant correlations in Puerto Rican male patients were found between PTK2 and PTK2B, NGFR, PDGFRB, EGFR, and CXCR1, which did not arise in non-Hispanic male patient data. The data for Puerto Rican female patients showed correlations in PTK2 with PTK2B, NGFR, PDGFRB, and EGFR, all of which did not appear in the data for non-Hispanic female patients. The data acquired from cBioPortal for non-Puerto Rican Hispanic patients supported the correlations found in the Puerto Rican population for both sexes. Our findings reveal distinct correlations in gene expression patterns, particularly involving PTK2, PTK2B, NGFR, PDGFRB, and EGFR among Puerto Rican Hispanic patients when compared to non-Hispanic counterparts.

The Tip of the Iceberg: Genotype of Puerto Rican Pediatric Obesity.

Childhood obesity is a significant public health concern, particularly among Hispanic populations. This study aimed to elucidate the genetic predisposition to obesity in Puerto Rican children of Hispanic descent, addressing a notable gap in existing research. A cohort of 103 children with obesity and hyperphagia underwent genetic screening for rare obesity-related variants. Clinical assessments and family history evaluations were conducted to characterize the demographic and clinical characteristics of the cohort. Genetic testing revealed a high prevalence of variants, with 73% of subjects having at least one reported variant. Pathogenic variants, predominantly associated with obesity-related ciliopathies, were identified in 7% of cases. Additionally, 90% of cases had variants of uncertain significance, highlighting the complexity of genetic contributions to obesity. This study emphasizes the critical need for further investigation into the genetic foundations of obesity, particularly within Hispanic communities. The findings emphasize the importance of early medical evaluation, vigilant monitoring for hyperphagia onset, and targeted interventions tailored to the unique genetic landscape of Puerto Rican children. This research provides a foundational framework for future studies to mitigate the impact of genetic obesity within this population.

A noncoding regulatory variant in IKZF1 increases acute lymphoblastic leukemia risk in Hispanic/Latino children.

Hispanic/Latino children have the highest risk of acute lymphoblastic leukemia (ALL) in the US compared to other racial/ethnic groups, yet the basis of this remains incompletely understood. Through genetic fine-mapping analyses, we identified a new independent childhood ALL risk signal near IKZF1 in self-reported Hispanic/Latino individuals, but not in non-Hispanic White individuals, with an effect size of ∼1.44 (95% confidence interval = 1.33-1.55) and a risk allele frequency of ∼18% in Hispanic/Latino populations and <0.5% in European populations. This risk allele was positively associated with Indigenous American ancestry, showed evidence of selection in human history, and was associated with reduced IKZF1 expression. We identified a putative causal variant in a downstream enhancer that is most active in pro-B cells and interacts with the IKZF1 promoter. This variant disrupts IKZF1 autoregulation at this enhancer and results in reduced enhancer activity in B cell progenitors. Our study reveals a genetic basis for the increased ALL risk in Hispanic/Latino children.

Germline pathogenic variants associated with triple-negative breast cancer in US Hispanic and Guatemalan women using hospital and community-based recruitment strategies.

PURPOSE: Recruit and sequence breast cancer subjects in Guatemalan and US Hispanic populations. Identify optimum strategies to recruit Latin American and Hispanic women into genetic studies of breast cancer. METHODS: We used targeted gene sequencing to identify pathogenic variants in 19 familial breast cancer susceptibility genes in DNA from unselected Hispanic breast cancer cases in the US and Guatemala. Recruitment across the US was achieved through community-based strategies. In addition, we obtained patients receiving cancer treatment at major hospitals in Texas and Guatemala. RESULTS: We recruited 287 Hispanic US women, 38 (13%) from community-based and 249 (87%) from hospital-based strategies. In addition, we ascertained 801 Guatemalan women using hospital-based recruitment. In our experience, a hospital-based approach was more efficient than community-based recruitment. In this study, we sequenced 103 US and 137 Guatemalan women and found 11 and 10 pathogenic variants, respectively. The most frequently mutated genes were BRCA1, BRCA2, CHEK2, and ATM. In addition, an analysis of 287 US Hispanic patients with pathology reports showed a significantly higher percentage of triple-negative disease in patients with pathogenic variants (41% vs. 15%). Finally, an analysis of mammography usage in 801 Guatemalan patients found reduced screening in women with a lower socioeconomic status (p < 0.001). CONCLUSION: Guatemalan and US Hispanic women have rates of hereditary breast cancer pathogenic variants similar to other populations and are more likely to have early age at diagnosis, a family history, and a more aggressive disease. Patient recruitment was higher using hospital-based versus community enrollment. This data supports genetic testing in breast cancer patients to reduce breast cancer mortality in Hispanic women.

The frequency of pathogenic variation in the All of Us cohort reveals ancestry-driven disparities.

Disparities in data underlying clinical genomic interpretation is an acknowledged problem, but there is a paucity of data demonstrating it. The All of Us Research Program is collecting data including whole-genome sequences, health records, and surveys for at least a million participants with diverse ancestry and access to healthcare, representing one of the largest biomedical research repositories of its kind. Here, we examine pathogenic and likely pathogenic variants that were identified in the All of Us cohort. The European ancestry subgroup showed the highest overall rate of pathogenic variation, with 2.26% of participants having a pathogenic variant. Other ancestry groups had lower rates of pathogenic variation, including 1.62% for the African ancestry group and 1.32% in the Latino/Admixed American ancestry group. Pathogenic variants were most frequently observed in genes related to Breast/Ovarian Cancer or Hypercholesterolemia. Variant frequencies in many genes were consistent with the data from the public gnomAD database, with some notable exceptions resolved using gnomAD subsets. Differences in pathogenic variant frequency observed between ancestral groups generally indicate biases of ascertainment of knowledge about those variants, but some deviations may be indicative of differences in disease prevalence. This work will allow targeted precision medicine efforts at revealed disparities.

Disparities in genetic testing for breast cancer among black and Hispanic women in the United States.

Women from racial and ethnic minorities are at a higher risk for developing breast cancer. Despite significant advancements in breast cancer screening, treatment, and overall survival rates, disparities persist among Black and Hispanic women. These disparities manifest as breast cancer at an earlier age with worse prognosis, lower rates of genetic screening, higher rates of advanced-stage diagnosis, and higher rates of breast cancer mortality compared to Caucasian women. The underutilization of available resources, such as genetic testing, counseling, and risk assessment tools, by Black and Hispanic women is one of many reasons contributing to these disparities. This review aims to explore the racial disparities that exist in genetic testing among Black and Hispanic women. Barriers that contribute to racial disparities include limited access to resources, insufficient knowledge and awareness, inconsistent care management, and slow progression of incorporation of genetic data and information from women of racial/ethnic minorities into risk assessment models and genetic databases. These barriers continue to impede rates of genetic testing and counseling among Black and Hispanic mothers. Consequently, it is imperative to address these barriers to promote early risk assessment, genetic testing and counseling, early detection rates, and ultimately, lower mortality rates among women belonging to racial and ethnic minorities.

Characterizing prostate cancer risk through multi-ancestry genome-wide discovery of 187 novel risk variants.

The transferability and clinical value of genetic risk scores (GRSs) across populations remain limited due to an imbalance in genetic studies across ancestrally diverse populations. Here we conducted a multi-ancestry genome-wide association study of 156,319 prostate cancer cases and 788,443 controls of European, African, Asian and Hispanic men, reflecting a 57% increase in the number of non-European cases over previous prostate cancer genome-wide association studies. We identified 187 novel risk variants for prostate cancer, increasing the total number of risk variants to 451. An externally replicated multi-ancestry GRS was associated with risk that ranged from 1.8 (per standard deviation) in African ancestry men to 2.2 in European ancestry men. The GRS was associated with a greater risk of aggressive versus non-aggressive disease in men of African ancestry (P = 0.03). Our study presents novel prostate cancer susceptibility loci and a GRS with effective risk stratification across ancestry groups.

Deregulated miRNA Expression in Triple-Negative Breast Cancer of Ancestral Genomic-Characterized Latina Patients.

Among patients with triple-negative breast cancer (TNBC), several studies have suggested that deregulated microRNA (miRNA) expression may be associated with a more aggressive phenotype. Although tumor molecular signatures may be race- and/or ethnicity-specific, there is limited information on the molecular profiles in women with TNBC of Hispanic and Latin American ancestry. We simultaneously profiled TNBC biopsies for the genome-wide copy number and miRNA global expression from 28 Latina women and identified a panel of 28 miRNAs associated with copy number alterations (CNAs). Four selected miRNAs (miR-141-3p, miR-150-5p, miR-182-5p, and miR-661) were validated in a subset of tumor and adjacent non-tumor tissue samples, with miR-182-5p being the most discriminatory among tissue groups (AUC value > 0.8). MiR-141-3p up-regulation was associated with increased cancer recurrence; miR-661 down-regulation with larger tumor size; and down-regulation of miR-150-5p with larger tumor size, high p53 expression, increased cancer recurrence, presence of distant metastasis, and deceased status. This study reinforces the importance of integration analysis of CNAs and miRNAs in TNBC, allowing for the identification of interactions among molecular mechanisms. Additionally, this study emphasizes the significance of considering the patients ancestral background when examining TNBC, as it can influence the relationship between intrinsic tumor molecular characteristics and clinical manifestations of the disease.

Evaluating genomic polygenic risk scores for childhood acute lymphoblastic leukemia in Latinos.

The utility of polygenic risk score (PRS) models has not been comprehensively evaluated for childhood acute lymphoblastic leukemia (ALL), the most common type of cancer in children. Previous PRS models for ALL were based on significant loci observed in genome-wide association studies (GWASs), even though genomic PRS models have been shown to improve prediction performance for a number of complex diseases. In the United States, Latino (LAT) children have the highest risk of ALL, but the transferability of PRS models to LAT children has not been studied. In this study, we constructed and evaluated genomic PRS models based on either non-Latino White (NLW) GWAS or a multi-ancestry GWAS. We found that the best PRS models performed similarly between held-out NLW and LAT samples (PseudoR2 = 0.086 ± 0.023 in NLW vs. 0.060 ± 0.020 in LAT), and can be improved for LAT if we performed GWAS in LAT-only (PseudoR2 = 0.116 ± 0.026) or multi-ancestry samples (PseudoR2 = 0.131 ± 0.025). However, the best genomic models currently do not have better prediction accuracy than a conventional model using all known ALL-associated loci in the literature (PseudoR2 = 0.166 ± 0.025), which includes loci from GWAS populations that we could not access to train genomic PRS models. Our results suggest that larger and more inclusive GWASs may be needed for genomic PRS to be useful for ALL. Moreover, the comparable performance between populations may suggest a more oligogenic architecture for ALL, where some large effect loci may be shared between populations. Future PRS models that move away from the infinite causal loci assumption may further improve PRS for ALL.

Efforts to Grow Genomic Research in Ancestrally Diverse and Admixed Populations.

Recent initiatives by the research community to characterize the genomic and molecular landscapes of tumors in ancestrally diverse and admixed populations, including the publication by Ding and colleagues in this issue of Cancer Research, represent important efforts to improve our understanding of the entire spectrum of cancer genomic variation with potential clinical consequences. Ding and colleagues confirmed a similar prevalence of mutations in established breast cancer driver genes including PIK3CA, TP53, GATA3, MAP3K1, CDH1, CBFB, PTEN, and RUNX1 and recurrent amplifications in breast cancer drivers including MYC, FGFR1, CCND1, and ERBB2 in tumors from Hispanic/Latina women as compared with non-Hispanic White women. Importantly, they also identified Catalogue of Somatic Mutations in Cancer (COSMIC) signature 16 in a significant fraction of tumors from Hispanic/Latina women and a novel recurrent amplification on 17q11.2. This study highlights the potential for inclusion of participants from diverse populations to accelerate discoveries and advance equity in genomic medicine, as well as the need for even larger collaborative initiatives. See related article by Ding et al., p. 2600.

Landmark Series: The Cancer Genome Atlas and the Study of Breast Cancer Disparities.

Race-related variation in breast cancer incidence and mortality are well-documented in the United States. The effect of genetic ancestry on disparities in tumor genomics, risk factors, treatment, and outcomes of breast cancer is less understood. The Cancer Genome Atlas (TCGA) is a publicly available resource that has allowed for the recent emergence of genome analysis research seeking to characterize tumor DNA and protein expression by ancestry as well as the social construction of race and ethnicity. Results from TCGA based studies support previous clinical evidence that demonstrates that American women with African ancestry are more likely to be afflicted with breast cancers featuring aggressive biology and poorer outcomes compared with women with other backgrounds. Data from TCGA based studies suggest that Asian women have tumors with favorable immune microenvironments and may experience better disease-free survival compared with white Americans. TCGA contains limited data on Hispanic/Latinx patients due to small sample size. Overall, TCGA provides important opportunities to define the molecular, biologic, and germline genetic factors that contribute to breast cancer disparities.

Profiling the Somatic Mutational Landscape of Breast Tumors from Hispanic/Latina Women Reveals Conserved and Unique Characteristics.

Somatic mutational profiling is increasingly being used to identify potential targets for breast cancer. However, limited tumor-sequencing data from Hispanic/Latinas (H/L) are available to guide treatment. To address this gap, we performed whole-exome sequencing (WES) and RNA sequencing on 146 tumors and WES of matched germline DNA from 140 H/L women in California. Tumor intrinsic subtype, somatic mutations, copy-number alterations, and expression profiles of the tumors were characterized and compared with data from tumors of non-Hispanic White (White) women in The Cancer Genome Atlas (TCGA). Eight genes were significantly mutated in the H/L tumors including PIK3CA, TP53, GATA3, MAP3K1, CDH1, CBFB, PTEN, and RUNX1; the prevalence of mutations in these genes was similar to that observed in White women in TCGA. Four previously reported Catalogue of Somatic Mutations in Cancer (COSMIC) mutation signatures (1, 2, 3, 13) were found in the H/L dataset, along with signature 16 that has not been previously reported in other breast cancer datasets. Recurrent amplifications were observed in breast cancer drivers including MYC, FGFR1, CCND1, and ERBB2, as well as a recurrent amplification in 17q11.2 associated with high KIAA0100 gene expression that has been implicated in breast cancer aggressiveness. In conclusion, this study identified a higher prevalence of COSMIC signature 16 and a recurrent copy-number amplification affecting expression of KIAA0100 in breast tumors from H/L compared with White women. These results highlight the necessity of studying underrepresented populations. SIGNIFICANCE: Comprehensive characterization of genomic and transcriptomic alterations in breast tumors from Hispanic/Latina patients reveals distinct genetic alterations and signatures, demonstrating the importance of inclusive studies to ensure equitable care for patients. See related commentary by Schmit et al., p. 2443.

Molecular and Sociodemographic Colorectal Cancer Disparities in Latinos Living in Puerto Rico.

BACKGROUND: The incidence of sporadic colorectal cancer (CRC) among individuals <50 years (early-onset CRC) has been increasing in the United States (U.S.) and Puerto Rico. CRC is currently the leading cause of cancer death among Hispanic men and women living in Puerto Rico (PRH). The objective of this study was to characterize the molecular markers and clinicopathologic features of colorectal tumors from PRH to better understand the molecular pathways leading to CRC in this Hispanic subpopulation. METHODS: Microsatellite instability (MSI), CpG island methylator phenotype (CIMP), and KRAS and BRAF mutation status were analyzed. Sociodemographic and clinicopathological characteristics were evaluated using Chi-squared and Fisher's exact tests. RESULTS: Of the 718 tumors analyzed, 34.2% (n = 245) were early-onset CRC, and 51.7% were males. Among the tumors with molecular data available (n = 192), 3.2% had MSI, 9.7% had BRAF, and 31.9% had KRAS mutations. The most common KRAS mutations observed were G12D (26.6%) and G13D (20.0%); G12C was present in 4.4% of tumors. A higher percentage of Amerindian admixture was significantly associated with early-onset CRC. CONCLUSIONS: The differences observed in the prevalence of the molecular markers among PRH tumors compared to other racial/ethnic groups suggest a distinct molecular carcinogenic pathway among Hispanics. Additional studies are warranted.

Clear cell renal cell carcinoma molecular variations in non-Hispanic White and Hispanic patients.

BACKGROUND: The United States is becoming increasingly diverse, but few molecular studies have assessed the progression of clear cell renal cell carcinoma (ccRCC) in diverse patient populations. This study examined ccRCC molecular variations in non-Hispanic White (NHW) and Hispanic patients and their effect on the association of gene expression with high-grade (Grade 3 or 4) ccRCC and overall mortality. METHODS: A total of 156 patients were included in VHL sequencing and/or TempO-Seq analysis. DESeq2 was used to identify the genes associated with high-grade ccRCC. Logistic regression analysis was performed to assess whether race and ethnicity was associated with high/moderate impact VHL somatic mutations and the ccA/ccB subtype. Cox regression analysis was performed to assess association of molecular subtype and gene expression with overall mortality. RESULTS: NHWs had moderate or high impact mutations in the VHL gene at a higher frequency than Hispanics (40.2% vs. 27.4%), while Hispanics had a higher frequency of the ccA subtype than NHWs (61.9% vs. 45.8%). ccA was more common in patients with BMI≥35 (65.2%) than in those with BMI < 25 (45.0%). There were 11 differentially expressed genes between high- and low-grade tumors. The Haptoglobin (HP) gene was most significantly overexpressed in high- compared to low-grade ccRCC in all samples (p-adj = 1.7 × 10-12 ). When stratified by subtype, the 11 genes were significantly differentially expressed in the ccB subtype, but none of them were significant after adjusting for multiple testing in ccA. Finally, patients with the ccB subtype had a significantly increased risk of overall mortality (HR 4.87; p = 0.01) compared to patients with ccA, and patients with high HP expression and ccB, had a significantly increased risk of mortality compared to those with low HP expression and ccA (HR 6.45, p = 0.04). CONCLUSION: This study reports ccRCC molecular variations in Hispanic patients who were previously underrepresented.

Racial and ethnic variation in BRCA1 and BRCA2 genetic test results among individuals referred for genetic counseling at a large urban comprehensive cancer center.

PURPOSE: The prevalence of pathogenic variants in BRCA1 and BRCA2 in populations other than Ashkenazi Jewish (AJ) is not well defined. We describe the racial and ethnic-specific prevalence of BRCA1/2 pathogenic variants and variants of uncertain significance (VUS) among individuals referred for genetic testing in a large urban comprehensive cancer center over a 20-year period. METHODS: The population included 3,537 unrelated individuals who underwent genetic testing from January 1999 to October 2019 at the Karmanos Cancer Institute. We estimated the prevalence of pathogenic variants and VUS and evaluated associations with race and ethnicity for African American (AA), Arab, AJ and Hispanic individuals compared to Non-Hispanic Whites (NHW). We used multivariable models to adjust for other predictors of pathogenic variants. We also reported the most common pathogenic variants by racial and ethnic group. RESULTS: The racial and ethnic breakdown of our population was: NHW (68.9%), AA (20.3%), AJ (2.5%), Arab (2.2%), Hispanic (1.0%), Asian Pacific Islander, Native American/Alaskan Native (4.7%), and < 1% unknown. The overall prevalence of pathogenic variants in BRCA1/2 was 8.9% and the prevalence of VUS was 5.6%. Compared to NHW, there were no racial or ethnic differences in the rate of pathogenic variants. However, AA individuals were more likely to have VUS in BRCA1 (adjusted OR 2.43, 95% CI 1.38-4.28) and AJ were more likely to have VUS in BRCA2 (adjusted OR 3.50, 95% CI 1.61-6.58). CONCLUSION: These results suggest the continued need for genetic testing and variant reclassification for individuals of all racial and ethnic groups.

Localized variation in ancestral admixture identifies pilocytic astrocytoma risk loci among Latino children.

BACKGROUND: Pilocytic astrocytoma (PA) is the most common pediatric brain tumor. PA has at least a 50% higher incidence in populations of European ancestry compared to other ancestral groups, which may be due in part to genetic differences. METHODS: We first compared the global proportions of European, African, and Amerindian ancestries in 301 PA cases and 1185 controls of self-identified Latino ethnicity from the California Biobank. We then conducted admixture mapping analysis to assess PA risk with local ancestry. RESULTS: We found PA cases had a significantly higher proportion of global European ancestry than controls (case median = 0.55, control median = 0.51, P value = 3.5x10-3). Admixture mapping identified 13 SNPs in the 6q14.3 region (SNX14) contributing to risk, as well as three other peaks approaching significance on chromosomes 7, 10 and 13. Downstream fine mapping in these regions revealed several SNPs potentially contributing to childhood PA risk. CONCLUSIONS: There is a significant difference in genomic ancestry associated with Latino PA risk and several genomic loci potentially mediating this risk.

Disparities in cancer genetics care by race/ethnicity among pan-cancer patients with pathogenic germline variants.

BACKGROUND: Germline risk assessment is increasing as part of cancer care; however, disparities in subsequent genetic counseling are unknown. METHODS: Pan-cancer patients were prospectively consented to tumor-normal sequencing via custom next generation sequencing panel (Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets) inclusive of germline analysis of ≥76 genes from January 2015 through December 2019 (97.5% research nonbillable) with protocol for genetics referral. Rates of pathogenic/likely pathogenic germline variants (PVs) and downstream counseling were compared across ancestry groups (mutually exclusive groups based on self-reported race/ethnicity and Ashkenazi Jewish [AJ] heritage) using nonparametric tests and multivariable logistic regression models. RESULTS: Among 15,775 patients (59.6%, non-Hispanic [NH]-White; 15.7%, AJ; 20.5%, non-White [6.9%, Asian; 6.8%, Black/African American (AA); 6.7%, Hispanic; 0.1%, Other], and 4.2%, unknown), 2663 (17%) had a PV. Non-White patients had a lower PV rate (n = 433, 13.4%) compared to NH-Whites (n = 1451, 15.4%) and AJ patients (n = 683, 27.6%), p < .01, with differences in mostly moderate and low/recessive/uncertain penetrance variants. Among 2239 patients with new PV, 1652 (73.8%) completed recommended genetic counseling. Non-White patients had lower rates of genetic counseling (67.7%) than NH-White (73.7%) and AJ patients (78.8%), p < .01, with lower rates occurring in Black/AA (63%) compared to NH-White patients, even after adjustment for confounders (odds ratio, 0.60; 95% confidence interval, 0.37-0.97; p = .036). Non-White, particularly Black/AA and Asian, probands had a trend toward lower rates and numbers of at-risk family members being seen for counseling/genetic testing. CONCLUSIONS: Despite minimizing barriers to genetic testing, non-White patients were less likely to receive recommended cancer genetics follow-up, with potential implications for oncologic care, cancer risk reduction, and at-risk family members. LAY SUMMARY: Genetic testing is becoming an important part of cancer care, and we wanted to see if genetics care was different between individuals of different backgrounds. We studied 15,775 diverse patients with cancer who had genetic testing using a test called MSK-IMPACT that was covered by research funding. Clinically important genetic findings were high in all groups. However, Black patients were less likely to get recommended counseling compared to White patients. Even after removing many roadblocks, non-White and especially Black patients were less likely to get recommended genetics care, which may affect their cancer treatments and families.

Germline Pathogenic Variant Prevalence Among Latin American and US Hispanic Individuals Undergoing Testing for Hereditary Breast and Ovarian Cancer: A Cross-Sectional Study.

PURPOSE: To report on pathogenic germline variants detected among individuals undergoing genetic testing for hereditary breast and/or ovarian cancer (HBOC) from Latin America and compare them with self-reported Hispanic individuals from the United States. METHODS: In this cross-sectional study, unrelated individuals with a personal/family history suggestive of HBOC who received clinician-ordered germline multigene sequencing were grouped according to the location of the ordering physician: group A, Mexico, Central America, and the Caribbean; group B, South America; and group C, United States with individuals who self-reported Hispanic ethnicity. Relatives who underwent cascade testing were analyzed separately. RESULTS: Among 24,075 unrelated probands across all regions, most were female (94.9%) and reported a personal history suggestive of HBOC (range, 65.0%-80.6%); the mean age at testing was 49.1 ± 13.1 years. The average number of genes analyzed per patient was highest in group A (A 63 ± 28, B 56 ± 29, and C 40 ± 28). Between 9.1% and 18.7% of patients had pathogenic germline variants in HBOC genes (highest yield in group A), with the majority associated with high HBOC risk. Compared with US Hispanics individuals the overall yield was significantly higher in both Latin American regions (A v C P = 1.64×10-9, B v C P < 2.2×10-16). Rates of variants of uncertain significance were similar across all three regions (33.7%-42.6%). Cascade testing uptake was low in all regions (A 6.6%, B 4.5%, and C 1.9%). CONCLUSION: This study highlights the importance of multigene panel testing in Latin American individuals with newly diagnosed or history of HBOC, who can benefit from medical management changes including targeted therapies, eligibility to clinical trials, risk-reducing surgeries, surveillance and prevention of secondary malignancy, and genetic counseling and subsequent cascade testing of at-risk relatives.