Clinical Cancer Genetics Disparities among Latinos.

The three major hereditary cancer syndromes in Latinos (Hereditary Breast and Ovarian Cancer, Familial Adenomatous Polyposis and Lynch Syndrome) have been shown to exhibit geographic disparities by country of origin suggesting admixture-based disparities. A solid infrastructure of clinical genetics geared towards diagnosis and prevention could aid in reducing the mortality of these cancer syndromes in Latinos. Currently, clinical cancer genetic services in Latin America are scarce. Moreover, limited studies have investigated the mutational spectrum of these cancer syndromes in Latinos resulting in gaps in personalized medicine affecting diagnosis, treatment and prevention. The following commentary discusses available genotype and clinical information on hereditary cancer in Latinos and highlights the limited access for cancer genetic services in Latin America including barriers to genetic testing and alternatives for providing better access to genetic services. In this review, we discuss the status of clinical genetic cancer services for both US Latinos and those Latinos living in Latin America.

Hereditary cancer syndromes in Latino populations: genetic characterization and surveillance guidelines.

Hereditary cancer predisposition syndromes comprise approximately 10% of diagnosed cancers; however, familial forms are believed to account for up to 30% of some cancers. In Hispanics, the most commonly diagnosed hereditary cancers include colorectal cancer syndromes such as, Lynch Syndrome, Familial Adenomatous Polyposis, and hereditary breast and ovarian cancer syndromes. Although the incidence of hereditary cancers is low, patients diagnosed with hereditary cancer syndromes are at high-risk for developing secondary cancers. Furthermore, the productivity loss that occurs after cancer diagnosis in these high-risk patients has a negative socio-economic impact. This review summarizes the genetic basis, phenotype characteristics, and the National Comprehensive Cancer Network's screening, testing, and surveillance guidelines for the leading hereditary cancer syndromes. The aim of this review is to promote a better understanding of cancer genetics and genetic testing in Hispanic patients.

Patient-specific induced pluripotent stem-cell-derived models of LEOPARD syndrome.

The generation of reprogrammed induced pluripotent stem cells (iPSCs) from patients with defined genetic disorders holds the promise of increased understanding of the aetiologies of complex diseases and may also facilitate the development of novel therapeutic interventions. We have generated iPSCs from patients with LEOPARD syndrome (an acronym formed from its main features; that is, lentigines, electrocardiographic abnormalities, ocular hypertelorism, pulmonary valve stenosis, abnormal genitalia, retardation of growth and deafness), an autosomal-dominant developmental disorder belonging to a relatively prevalent class of inherited RAS-mitogen-activated protein kinase signalling diseases, which also includes Noonan syndrome, with pleomorphic effects on several tissues and organ systems. The patient-derived cells have a mutation in the PTPN11 gene, which encodes the SHP2 phosphatase. The iPSCs have been extensively characterized and produce multiple differentiated cell lineages. A major disease phenotype in patients with LEOPARD syndrome is hypertrophic cardiomyopathy. We show that in vitro-derived cardiomyocytes from LEOPARD syndrome iPSCs are larger, have a higher degree of sarcomeric organization and preferential localization of NFATC4 in the nucleus when compared with cardiomyocytes derived from human embryonic stem cells or wild-type iPSCs derived from a healthy brother of one of the LEOPARD syndrome patients. These features correlate with a potential hypertrophic state. We also provide molecular insights into signalling pathways that may promote the disease phenotype.

Multiple hemangiomas in a patient with a t(3q;4p) translocation: an infrequent association with Wolf-Hirschhorn syndrome.

We report on the clinical phenotype of an infant with a duplication of the terminal portion of the long arm of chromosome 3(q26.3-qter) and a deletion of the terminal portion of the short arm of chromosome 4(p16.3) with multiple hemangiomas and a hamartoma. Patients with deletions of distal 4p have the characteristic features of Wolf-Hirschhorn syndrome (WHS); whereas those with the distal duplication of 3q have a well recognized syndrome with some features resembling Cornelia-de Lange syndrome (CdLS). Neither of these recognized chromosomal anomalies has been reported previously to be associated with multiple hemangiomas or other vascular malformations.

An atypical deletion of the Williams-Beuren syndrome interval implicates genes associated with defective visuospatial processing and autism.

BACKGROUND: During a genetic study of autism, a female child who met diagnostic criteria for autism spectrum disorder, but also exhibited the cognitive-behavioural profile (CBP) associated with Williams-Beuren syndrome (WBS) was examined. The WBS CBP includes impaired visuospatial ability, an overly friendly personality, excessive non-social anxiety and language delay. METHODS: Using array-based comparative genomic hybridisation (aCGH), a deletion corresponding to BAC RP11-89A20 in the distal end of the WBS deletion interval was detected. Hemizygosity was confirmed using fluorescence in situ hybridisation and fine mapping was performed by measuring the copy number of genomic DNA using quantitative polymerase chain reaction. RESULTS: The proximal breakpoint was mapped to intron 1 of GTF2IRD1 and the distal breakpoint lies 2.4-3.1 Mb towards the telomere. The subject was completely hemizygous for GTF2I, commonly deleted in carriers of the classic approximately 1.5 Mb WBS deletion, and GTF2IRD2, deleted in carriers of the rare approximately 1.84 Mb WBS deletion. CONCLUSION: Hemizygosity of the GTF2 family of transcription factors is sufficient to produce many aspects of the WBS CBP, and particularly implicate the GTF2 transcription factors in the visuospatial construction deficit. Symptoms of autism in this case may be due to deletion of additional genes outside the typical WBS interval or remote effects on gene expression at other loci.

Prevalence and Genetic Profile of Duchene and Becker Muscular Dystrophy in Puerto Rico.

BACKGROUND: Duchenne and Becker Muscular Dystrophy (DMD and BMD, respectively), are common forms of inherited muscle disease. Information regarding the epidemiology of these conditions, including genotype, is still sparse. OBJECTIVE: To establish the prevalence and genetic profile of DMD and BMD in Puerto Rico. METHODS: We collected data from medical records in all Muscular Dystrophy Association (MDA) clinics in Puerto Rico in order to estimate the prevalence of DMD and BMD and to describe the genotypic profile of these patients. Patients selected for data analysis matched "definite", "probable" and "possible" case definitions as established by MD STARnet. RESULTS: A total of 141 patients matched the inclusion criteria, with 64.5% and 35.5% being categorized into DMD and BMD, respectively. DMD and BMD prevalence in Puerto Rico was estimated at 5.18 and 2.84 per 100,000 males, respectively. Deletion was the most common form of mutation (66.7%) in the dystrophin gene, with exons in segment 45 to 47 being the most frequently affected. CONCLUSIONS: This is the first report of the prevalence and genetic profile characteristics of DMD and BMD in Puerto Rico. Prevalence of DMD was similar to that reported worldwide, while prevalence of BMD was higher. Genetic profile was consistent with that reported in the literature.

Limb-Girdle Muscular Dystrophy Type 2A Resulting From c.C479G and c.G1818A Mutations in the Calpain-3 Gene.

Limb-Girdle Muscular Dystrophy type 2A (LGMD2A) is an autosomal recessive disorder characterized by progressive weakness of proximal muscles. Here, we describe a patient with clinical features consistent with LGMD2A who harbors 2 rare changes in the CAPN3 gene sequence of unknown clinical significance. Mechanisms by which these 2 mutations could affect the protein are discussed. The c.C479G mutation seems to affect the proteolytic domain of calpain-3. Whereas the novel mutation c.G1818A seems to affect mRNA translation of the protein region involved in titin binding. We strongly believe that these genomic variants in CAPN3 are indeed deleterious and thus are currently misclassified. Since LGMD2 is considered a disorder of autosomal recessive inheritance, further population studies involving the molecular characterization of symptomatic patients must be performed as well as in vitro studies to ascertain the functional effects of these specific variants.

Clinical characterization and mutation spectrum in Caribbean Hispanic families with Lynch syndrome.

Lynch syndrome (LS) is an inherited form of colorectal cancer (CRC) caused by germline mutations in the mismatch repair (MMR) genes. It accounts for approximately 5% of all CRCs. The prevalence of LS among US Hispanics is unknown. The objective of this study was to describe the germline mutations of LS in Caribbean Hispanics from Puerto Rico and Dominican Republic. A total of 89 subjects were recruited through the Puerto Rico Familial Colorectal Cancer Registry and were classified according to Amsterdam and Bethesda clinical guidelines. For those tumors with lack of expression of MMR protein, gene sequencing was ordered. A total of 35 individuals with deficient MMR system were identified: 22 had MMR mutations and 13 had tumors with absent MMR protein expression. Our results show that the mutation spectrum of Caribbean Hispanic LS patients was composed mostly of MSH2 (66.7%) mutations, followed by MLH1 (25.0%). One mutation was identified in MSH6 (8.3%). A previously unidentified mutation in MLH1 gene c.2044_2045del was found in one Caribbean Hispanic family. MMR mutation-positive individuals were found to be more likely to have a prominent family history of CRC and tumors located at the proximal colon. Compared to MSH2 mutation carriers, MLH1 mutation-positive individuals were more likely to have a strong family history of CRC and LS associated cancers. Furthermore, insurance coverage for genetic testing was found to be limited in the study population with 65.1% of the individuals recruited were denied coverage. This report presents the first description of the mutation spectrum and clinicopathologic characteristics of LS Caribbean Hispanics patients.

Myeloid Dysregulation in a Human Induced Pluripotent Stem Cell Model of PTPN11-Associated Juvenile Myelomonocytic Leukemia.

Somatic PTPN11 mutations cause juvenile myelomonocytic leukemia (JMML). Germline PTPN11 defects cause Noonan syndrome (NS), and specific inherited mutations cause NS/JMML. Here, we report that hematopoietic cells differentiated from human induced pluripotent stem cells (hiPSCs) harboring NS/JMML-causing PTPN11 mutations recapitulated JMML features. hiPSC-derived NS/JMML myeloid cells exhibited increased signaling through STAT5 and upregulation of miR-223 and miR-15a. Similarly, miR-223 and miR-15a were upregulated in 11/19 JMML bone marrow mononuclear cells harboring PTPN11 mutations, but not those without PTPN11 defects. Reducing miR-223's function in NS/JMML hiPSCs normalized myelogenesis. MicroRNA target gene expression levels were reduced in hiPSC-derived myeloid cells as well as in JMML cells with PTPN11 mutations. Thus, studying an inherited human cancer syndrome with hiPSCs illuminated early oncogenesis prior to the accumulation of secondary genomic alterations, enabling us to discover microRNA dysregulation, establishing a genotype-phenotype association for JMML and providing therapeutic targets.

RAF1 mutations in childhood-onset dilated cardiomyopathy.

Dilated cardiomyopathy (DCM) is a highly heterogeneous trait with sarcomeric gene mutations predominating. The cause of a substantial percentage of DCMs remains unknown, and no gene-specific therapy is available. On the basis of resequencing of 513 DCM cases and 1,150 matched controls from various cohorts of distinct ancestry, we discovered rare, functional RAF1 mutations in 3 of the cohorts (South Indian, North Indian and Japanese). The prevalence of RAF1 mutations was ~9% in childhood-onset DCM cases in these three cohorts. Biochemical studies showed that DCM-associated RAF1 mutants had altered kinase activity, resulting in largely unaltered ERK activation but in AKT that was hyperactivated in a BRAF-dependent manner. Constitutive expression of these mutants in zebrafish embryos resulted in a heart failure phenotype with AKT hyperactivation that was rescued by treatment with rapamycin. These findings provide new mechanistic insights and potential therapeutic targets for RAF1-associated DCM and further expand the clinical spectrum of RAF1-related human disorders.