Inborn errors of purine and pyrimidine metabolism: how much we owe to H. Anne Simmonds.

Purines and pyrimidines, regarded for a long time merely as building blocks for nucleic acid synthesis and intermediates in the transfer of metabolic energy, have attracted increasing attention after genetically determined aberrations in their metabolism were linked to a range of symptoms from hyperuricemia and immunodeficiency to neurological disorders. The pathogenesis of such disorders involves cell or mitochondrial damage, but the molecular mechanisms underlying symptoms is often unclear. H. Anne Simmonds made major contributions to the metabolic, clinical, and molecular aspects of these disorders and the Purine Research Laboratory, which she established in London, became the world center for clinical and experimental studies in the field. We owe her gratitude not only for this direct contribution but also for her enthusiasm for purine and pyrimidine research that she transmitted to generations of scientists. Our research in this field stemmed from expertise in pyridine metabolism and its connection with purines, and from clinical involvement with biochemical diagnosis of enzyme deficiencies. We joined H. Anne Simmonds in studying the biochemical basis of altered NAD content in erythrocytes of PNP- and HPRT-deficient patients, discovering some alterations in NAD synthesis and breakdown.