ANCESTRY IN PUERTO RICO 2019

[Argentano]

PUERTO RICO

https://www.frontiersin.org/articles...019.00538/full


Introduction: Puerto Ricans, the second largest Latino group in the continental US, are underrepresented in genomic studies of Alzheimer disease (AD). To increase representation of this group in genomic studies of AD, we developed a multisource ascertainment approach to enroll AD patients, and their family members living in Puerto Rico (PR) as part of the Alzheimer’s Disease Sequencing Project (ADSP), an international effort to advance broader personalized/precision medicine initiatives for AD across all populations.

Methods: The Puerto Rico Alzheimer Disease Initiative (PRADI) multisource ascertainment approach was developed to recruit and enroll Puerto Rican adults aged 50 years and older for a genetic research study of AD, including individuals with cognitive decline (AD, mild cognitive impairment), their similarly, aged family members, and cognitively healthy unrelated individuals age 50 and up. Emphasizing identification and relationship building with key stakeholders, we conducted ascertainment across the island. In addition to reporting on PRADI ascertainment, we detail admixture analysis for our cohort by region, group differences in age of onset, cognitive level by region, and ascertainment source.

Results: We report on 674 individuals who met standard eligibility criteria [282 AD-affected participants (42% of the sample), 115 individuals with mild cognitive impairment (MCI) (17% of the sample), and 277 cognitively healthy individuals (41% of the sample)]. There are 43 possible multiplex families (10 families with 4 or more AD-affected members and 3 families with 3 AD-affected members). Most individuals in our cohort were ascertained from the Metro, Bayamón, and Caguas health regions. Across health regions, we found differences in ancestral backgrounds, and select clinical traits.

Discussion: The multisource ascertainment approach used in the PRADI study highlights the importance of enlisting a broad range of community resources and providers. Preliminary results provide important information about our cohort that will be useful as we move forward with ascertainment. We expect that results from the PRADI study will lead to a better understanding of genetic risk for AD among this population.


Admixture Results
We examined the population structure of Puerto Ricans using the supervised ADMIXTURE analysis at K = 3. Figure 3A illustrates the results from the ADMIXTURE analysis in a bar-plot figure. Each vertical bar represents an individual and corresponding estimates of the fraction of continental ancestries (African, European, and Native American). On average, Puerto Ricans have mostly European ancestry with a mean value of 69.3% (SD = 12.2). Mean values for African and Native American ancestry are 17.3% (SD = 12.2) and 13.4% (SD = 4.2), respectively as seen in the box plots (Figure 3B).







We observed a non-uniform distribution of European and African ancestral backgrounds across the health regions with relatively high European and low African ancestral proportions in Mayagüez, Ponce, and Bayamón (Figure 4B). The average European and African ancestry fractions in these zones are 74.4% (s = 5.8), 74% (SD = 8.1), 73.3% (SD = 8.7) and 11.9% (SD = 6.6), 11.6% (SD = 5.9), 11.0% (SD = 4.9), respectively. In contrast, the Native American ancestral background shows nearly uniform distribution across the geographical zones (Figure 4B).

[Argentano]

Looking at the regional results, it seems that most regions are pred euro tri racial but some are more african (Metro) and others more amerindian (Bayamon, Fajardo, Mayaguez)

[Argentano]

As other studies have previously shown

- its quite rare for a puerto rican to be less than 50% european
- pred SSA puerto ricans are extremely rare.
-Most PR score some amerindian

[Argentano]

According too this study

PUERTO RICO european 69.3% African 17.3% and Native American 13.4%


AND majority of the samples in this study come from the less euro area (metro)

[time67]

As other studies have previously shown

- its quite rare for a puerto rican to be less than 50% european
- pred SSA puerto ricans are extremely rare.
-Most PR score some amerindian

Most are probably concentrated in Loiza.

[perikolez]

According too this study

PUERTO RICO european 69.3% African 17.3% and Native American 13.4%


AND majority of the samples in this study come from the less euro area (metro)

Puerto Rico is the most european caribean island with the exception of Saint Barthelemy.

[Argentano]

Puerto Rico is the most european caribean island with the exception of Saint Barthelemy.

something that IMO makes PUR very euro is that its very colonial and homogeneous. Maybe you dont find many whites but most of the individuals are at least 50% euro so its impossible for them to be below 60% euro on average.

The puerto ricans we have added in gedmatch are almost identical to this study, 73% euro and very homogeneous. All the euro is spanish.

[SilverKnight]

Puerto Rico is the most european caribean island with the exception of Saint Barthelemy.

Followed by Cuba in 2nd place, and then DR in 3rd, all 3 very Colonial.. Cuba though has a large pool of people with over 75 % European, whom many have moved to the US in the last 4 decades

[Erronkari]

Is "Metro" San Juan area?

[BirdMan]

Yes - but they didn't define all of the regions in a traditional way (Bayamon is always included in the definition and occasionally Caguas as well),

Traditional definition of Área Metro