Genome-wide association analysis and admixture mapping in a Puerto Rican cohort supports an Alzheimer disease risk locus on chromosome 12.

Introduction: Hispanic/Latino populations are underrepresented in Alzheimer Disease (AD) genetic studies. Puerto Ricans (PR), a three-way admixed (European, African, and Amerindian) population is the second-largest Hispanic group in the continental US. We aimed to conduct a genome-wide association study (GWAS) and comprehensive analyses to identify novel AD susceptibility loci and characterize known AD genetic risk loci in the PR population. Materials and methods: Our study included Whole Genome Sequencing (WGS) and phenotype data from 648 PR individuals (345 AD, 303 cognitively unimpaired). We used a generalized linear-mixed model adjusting for sex, age, population substructure, and genetic relationship matrix. To infer local ancestry, we merged the dataset with the HGDP/1000G reference panel. Subsequently, we conducted univariate admixture mapping (AM) analysis. Results: We identified suggestive signals within the SLC38A1 and SCN8A genes on chromosome 12q13. This region overlaps with an area of linkage of AD in previous studies (12q13) in independent data sets further supporting. Univariate African AM analysis identified one suggestive ancestral block (p = 7.2×10-6) located in the same region. The ancestry-aware approach showed that this region has both European and African ancestral backgrounds and both contributing to the risk in this region. We also replicated 11 different known AD loci -including APOE- identified in mostly European studies, which is likely due to the high European background of the PR population. Conclusion: PR GWAS and AM analysis identified a suggestive AD risk locus on chromosome 12, which includes the SLC38A1 and SCN8A genes. Our findings demonstrate the importance of designing GWAS and ancestry-aware approaches and including underrepresented populations in genetic studies of AD.

Linkage of Alzheimer disease families with Puerto Rican ancestry identifies a chromosome 9 locus.

The genetic admixture of Caribbean Hispanics provides an opportunity to discover novel genetic factors in Alzheimer disease (AD). We sought to identify genetic variants for AD through a family-based design using the Puerto Rican (PR) Alzheimer Disease Initiative (PRADI). Whole-genome sequencing (WGS) and parametric linkage analysis were performed for 100 individuals from 23 multiplex PRADI families. Variants were prioritized by minor allele frequency (<0.01), functional potential [combined annotation dependent depletion score (CADD) >10], and co-segregation with AD. Variants were further ranked using an independent PR case-control WGS dataset (PR10/66). A genome-wide significant linkage peak was found in 9p21 with a heterogeneity logarithm of the odds score (HLOD) >5.1, which overlaps with an AD linkage region from two published independent studies. The region harbors C9orf72, but no expanded repeats were observed in the families. Seven variants prioritized by the PRADI families also displayed evidence for association in the PR10/66 (p < 0.05), including a missense variant in UNC13B. Our study demonstrated the importance of family-based design and WGS in genetic study of AD.

'Fit Moms/Mamás Activas' internet-based weight control program with group support to reduce postpartum weight retention in low-income women: study protocol for a randomized controlled trial.

BACKGROUND: High postpartum weight retention is a strong independent risk factor for lifetime obesity, cardiovascular disease, and type 2 diabetes in women. Interventions to promote postpartum weight loss have met with some success but have been limited by high attrition. Internet-based treatment has the potential to overcome this barrier and reduce postpartum weight retention, but no study has evaluated the effects of an internet-based program to prevent high postpartum weight retention in women. METHODS/DESIGN: Fit Moms/Mamás Activas targets recruitment of 12 Women, Infants and Children (WIC) Supplemental Nutrition Program clinics with a total of 408 adult (>18 years), postpartum (<1 year) women with 14.5 kg or more weight retention or a body mass index of 25.0 kg/m(2) or higher. Clinics are matched on size and randomly assigned within county to either a 12-month standard WIC intervention or to a 12-month WIC enhanced plus internet-based weight loss intervention. The intervention includes: monthly face-to-face group sessions; access to a website with weekly lessons, a web diary, instructional videos, and computer-tailored feedback; four weekly text messages; and brief reinforcement from WIC counselors. Participants are assessed at baseline, six months, and 12 months. The primary outcome is weight loss over six and 12 months; secondary outcomes include diet and physical activity behaviors, and psychosocial measures. DISCUSSION: Fit Moms/Mamás Activas is the first study to empirically examine the effects of an internet-based treatment program, coupled with monthly group contact at the WIC program, designed to prevent sustained postpartum weight retention in low-income women at high risk for weight gain, obesity, and related comorbidities. TRIAL REGISTRATION: This trial was registered with Clinicaltrials.gov (identifier: NCT01408147 ) on 29 July 2011.