In 2014 I had my genome run on 23andMe and through digging and getting a second genome run I confirmed that I was homozygous for rs1049564 (and other SNPs) in my PNP gene.
I was finally able to push for a PNP activity test which revealed low activity. I do not think the doctors would have ever tested for this.
Here is the paper that persuaded them to do the test: https://www.researchgate.net/figure/Purine-nucleoside-phosph...
Since it is only a partial deficiency it did not cause catastrophic effects as a child, but as I got older it became worse.
Here is a paper talking about the partial deficiency: https://pubmed.ncbi.nlm.nih.gov/32695102/
I also have neurological issues (mood disorder) that I blame on the same deficiency.