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Collection of genetic data in population‐based studies across urban and rural areas: The challenges of the Mexican Health and Aging Study: Biomarkers (non‐neuroimaging) / Method development and/or quality control
Abstract Background The Mexican Health and Aging Study is a longitudinal study aimed to evaluate the impact of age‐related diseases among adults 50 years and older in both urban and rural areas of Mexico. Over a 20‐year follow‐up period the study has collected data on cognitive function, health and...
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| Published in: | Alzheimer's & dementia 2020-12, Vol.16 (S4) |
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| Main Authors: | , , , , , , , |
| Format: | Article |
| Language: | English |
| Online Access: | Request full text |
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| Summary: | Abstract
Background
The Mexican Health and Aging Study is a longitudinal study aimed to evaluate the impact of age‐related diseases among adults 50 years and older in both urban and rural areas of Mexico. Over a 20‐year follow‐up period the study has collected data on cognitive function, health and socio‐economic factors among the study participants. In addition, blood and saliva samples are available from 2,800 and 7,862 participants respectively. The DNA extracted from blood and saliva samples will be used to conduct downstream genetic analyses.
Method
The saliva collection cohort consisted of participants aged 60 and older from the Mexican Health and Aging Study willing and able to provide a sample. Interviewers across Mexico were trained to collect and ship the saliva samples to the headquarters of the National Institute of Statistics (INEGI) in Aguascalientes, Mexico. Saliva samples passing quality control process were sent to the National Centralized Repository for Alzheimer’s Disease and Related Dementias (NCRAD) in Indiana, for DNA extraction and storage. DNA samples were distributed to different institutions for genetic analysis:
APOE
genotyping was conducted at LGC Genomics and genome wide genotyping at the Children’s Hospital of Philadelphia. A subset of the samples were subject to whole genome sequencing conducted by the Uniformed Services University of the Health Sciences.
Result
A total of 8,156 saliva samples were collected of which 279 failed customs clearance for shipment from Mexico to the USA. 0.23% samples were dropped at extraction and 0.23% failed DNA quality standards for genotyping. A total of 7,832 samples were used for
APOE
, genome‐wide genotyping and whole genome sequencing.
Conclusion
Sample collection for genetic studies in remote rural areas of developing countries such as Mexico present important logistical challenges. The use of saliva as a main source of DNA provides a non‐invasive, low cost, effective and feasible alternative to blood sample collection. Our results suggest that similar protocols can take place in other under‐represented populations of Latin America. Future work will aim to augment the analytical power of the cohort by collecting saliva samples from additional subjects of the MHAS cohort. |
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| ISSN: | 1552-5260 1552-5279 |
| DOI: | 10.1002/alz.045579 |