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However, this delay in diagnosis and treatment for SMA sadly resulted in the patient dying from respiratory
complications a couple of months later.

THE FUTURE AND EQUITY OF NEWBORN SCREENING
The development and implementation of next-generation genomic sequencing for the study of genetic
disorders and, later on, for molecular clinical diagnostics of patients with rare genetic disorders has raised
the possibility of utilizing genomic sequencing as a newborn screening tool. The utilization of modern
genomic sequencing technologies offers the possibility to identify actionable genetic diseases promptly
before symptom onset and beyond the limitations of identifying abnormal metabolites through MS/MS in
ENBS. In the last few years, several pilot programs have been implemented to evaluate the feasibility,
effectiveness, and impact of genomic newborn screening (gNBS) in sick and healthy newborns primarily in
the United States and the United Kingdom [16-19] . Currently, at least thirty different gNBS programs are being
planned or implemented on a research basis or commercially in Europe, the US, the UK, China, and
Australia [20,21] . Issues regarding how many and which conditions to include, data analysis and variant
interpretation, return of results, data privacy and storage, and data revisiting and custody are among the
main themes that are being explored and discussed for gNBS programs [19-21] . While promising to improve
the lives of millions of newborns in the corresponding countries, the current landscape of gNBS programs
further reflects the disparities in the implementation of genomic sequencing for precision health around the
world. The lack of representation of non-European ancestry individuals in genomic projects and databases
is now a well-recognized problem, yet slow progress has been made in expanding genomic sequencing
efforts to underrepresented populations . A particular issue related to this is the interpretation of genomic
[22]
data and variants for individuals from underrepresented populations like those in LAC. Studies that have
assessed the diagnostic efficacy of genomic sequencing in patients from different ancestries, have shown a
higher proportion of variants of unknown significance and a reduction in diagnostic efficacy for patients
from admixed populations such as Hispanics and African Americans in the US [23,24] . The implementation of
population-level genomics programs, including gNBS, can help not only expand the characterization of
human genomic variation, but also clarify the clinical significance of variants of unknown significance for
individuals from underrepresented populations in both high-income (HIC) and low- and middle-income
countries (LMICs).

The question is not anymore whether gNBS should be done because research programs exploring its
feasibility are already being planned or implemented in several countries, but what the best practices for
these programs should be, their advantages and limitations, and how to ensure the equitable
implementation of genomic technologies to reduce and not broaden health disparities around the
world [18,25] . While HICs are already implementing research gNBS pilot programs to assess their feasibility for
public health, LMICs like Mexico and most other LAC countries are tracking behind on the implementation
of genomic technologies for the research and diagnosis of genetic diseases, let alone exploring their
implementation at the population level or in gNBS programs. This gap in implementation is multifactorial,
but a major factor is the cost of local genomic sequencing in LMICs, which can be 3-5 times higher than in
HICs due to high import fees and taxes plus distributor fees for instruments and reagents.

Mexico was the first country in LAC to initiate NBS eleven years after NBS was mandated and implemented
in some states in the United States, while other LAC countries have not yet implemented basic NBS
programs. Proof of concept for the need to implement ENBS in Mexico was published in 2000 , yet more
[26]
than two decades later, ENBS is not being performed for most newborns in the country. Are the countries
in the LAC region going to maintain this trend and explore implementing gNBS a decade or more later than
more advanced countries?