Puerto Rico leads the U.S. in rare diseases.
Who can diagnose them?

The government announced that Puerto Rico is the U.S. jurisdiction with the most rare diseases, and that it will build an official registry of who has them. This record looks at the other side of the problem: the capacity to diagnose them that already exists today, counted with federal data. Because a disease no one can identify is as serious as one that does not exist.

What the news says

On April 11, 2025, Law 9-2025 was signed, creating the Office for the Support and Registry of People with Rare Diseases (OER), under the Department of Health, with a $450,000 budget. Its director, Dr. Fernando Ocasio, told El Vocero that the office "is developing the interface for what will be the registry" and that so far it has identified 42 rare diseases on the island, of the roughly 7,000 catalogued worldwide.

A disease is considered "rare" when it affects fewer than 2 in every 10,000 people. The president of the College of Physicians-Surgeons, Dr. Carlos Díaz, noted that "the system is not agile, not fast," and that insurers question and deny the specialized studies needed to reach a diagnosis.

Why it hits Boricuas harder

The reason has a name: the founder effect. Puerto Rico's population comes from a mix of three roots (Taíno, Spanish and African) and from groups that stayed isolated for generations. When a mutation enters a small group and that group grows more or less among itself, the mutation becomes far more common than in the rest of the world.

That makes certain rare genetic diseases, here, less rare. Albinism, for example, appears in about 1 in 20,000 people in Puerto Rico, and HPS-3 syndrome (a type of albinism with bleeding problems) concentrates in specific mountain towns: Comerío, Naranjito and Barranquitas. Boricua genetics is not a trivia fact. It draws a map.

The bottleneck no one counted: who can diagnose

Diagnosing a rare disease almost always requires a clinical geneticist: a physician trained to read DNA and name what other specialists cannot find. We searched the federal NPPES registry for how many exist in Puerto Rico. This is the count, verified one by one (July 2026):

The 2 clinical geneticists (M.D.) who diagnose patients are in Santurce and Manatí. Counting the clinical genetics subspecialties (molecular and biochemical), there are 4, and four of them share the same building on Calle San Jorge in Santurce. In practice, clinical genetics for all of Puerto Rico runs from a handful of metro offices. Source: federal NPPES registry (taxonomies 207SG0201X, 207SG0202X, 207SG0203X, 170300000X).

And the mutations concentrate where no one is

This is where the two maps cross. Founder mutations concentrate in the mountains and in specific towns. The specialists who diagnose and manage them (geneticists, neurologists, pediatricians) concentrate in the metro. See the Atlas of Boricua founder diseases, one by one and by town →

We looked at our database, verified against NPPES, for the central mountain region:

The central mountain region (the same one where founder mutations concentrate) has 1 neurologist, 0 neurosurgeons and 0 geneticists for the entire region. A family from Comerío or Barranquitas with a child who needs a geneticist drives two hours or more to reach Santurce. That is once they already know they need a geneticist. Most do not know yet. That is the real meaning of the "diagnostic odyssey": it is not only that the science is hard, it is that no one knows whom to see or where they are.

The odyssey, in a family with a name

Melissmar López Pimentel was born in 2007. Her parents spent 11 years looking for answers before, in 2018, she was diagnosed with TBCK syndrome, a neurogenetic disease with a founder variant identified in Puerto Rico. That is why it is known as the "Boricua Syndrome" (the p.R126X mutation). There are about 100 diagnosed cases worldwide; the foundation her parents created has identified around 21 families in Puerto Rico alone.

Promised vs. delivered

The government set goals: interoperable data infrastructure and covering 75% of identifiable cases by 2030. It is a good promise. It is also a five-year promise, with $450,000, starting from 42 catalogued diseases and not yet knowing how many people have them or in what towns they live. We will track that promise, year by year, at Puerto Rico Sin Filtros. This record keeps the other side: who can diagnose today, and where.

Citable data

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