# Stephen J. Gould
**Stephen J. Gould** is an American molecular biologist, a professor at the Johns Hopkins University School of Medicine. Not to be confused with [Stephen Jay Gould](https://www.edgepedia.org/stephen-jay-gould), the paleontologist and essayist.
| Key facts | |
|---|---|
| Field | Molecular biology: protein trafficking, peroxisome biogenesis, exosome biology[1](https://profiles.hopkinsmedicine.org/provider/stephen-j-gould/2777555) |
| Position | Professor, Johns Hopkins University School of Medicine (full professor since 2002)[1](https://profiles.hopkinsmedicine.org/provider/stephen-j-gould/2777555) |
| Training | B.A. University of California, Santa Barbara, 1984; Ph.D. University of California, San Diego, 1989; postdoctoral training at UC San Diego[1](https://profiles.hopkinsmedicine.org/provider/stephen-j-gould/2777555) |
| Signature work | "Mutations in PEX1 are the most common cause of peroxisome biogenesis disorders," Nature Genetics, 1997[2](https://doi.org/10.1038/ng1297-445) |
| Gene discoveries | several gene discoveries in 1997, including PEX1, PEX12, and PAHX/Refsum disease |[2](https://doi.org/10.1038/ng1297-445) • [3](https://doi.org/10.1038/ng0497-385) • [4](https://europepmc.org/article/MED/9326939)
| Current research | Exosome biogenesis and engineering, exosome-based vaccines and therapeutics, chronic pain, retrovirus budding, SARS-CoV-2 spike cell biology[5](https://cellbio.jhmi.edu/people/stephen-gould-ph-d/) |
| Service roles | Founder, American Society for Exosomes and Microvesicles; founding board member, American Association for Extracellular Vesicles; editor of exosome.org[1](https://profiles.hopkinsmedicine.org/provider/stephen-j-gould/2777555) |
## Education and career
Gould received his B.A. in marine biology from the [University of California, Santa Barbara](https://www.edgepedia.org/university-of-california-santa-barbara) in 1984, his Ph.D. in biology from the [University of California, San Diego](https://www.edgepedia.org/university-of-california-san-diego) in 1989, and carried out his postdoctoral training at UC San Diego.[1](https://profiles.hopkinsmedicine.org/provider/stephen-j-gould/2777555) He joined the [Johns Hopkins](https://www.edgepedia.org/johns-hopkins) faculty in 1991 as an assistant professor, became an associate professor in 1998, and a full professor in 2002.[1](https://profiles.hopkinsmedicine.org/provider/stephen-j-gould/2777555) His Hopkins profile places him in the Department of Biological Chemistry; his laboratory site lists the Department of Cell Biology.[1](https://profiles.hopkinsmedicine.org/provider/stephen-j-gould/2777555) • [6](https://sgouldlab.com/team-members/about-pi/) His research interests lie at the intersection of protein trafficking and human disease.[1](https://profiles.hopkinsmedicine.org/provider/stephen-j-gould/2777555) The Johns Hopkins research portal records his output from 1986 to 2025, including 116 articles and 12 review articles.[7](https://pure.johnshopkins.edu/en/persons/stephen-gould/)
## Representative work
Gould's December 1997 [Nature Genetics](https://www.edgepedia.org/nature-genetics) paper, Mutations in PEX1 are the most common cause of peroxisome biogenesis disorders, identified the human orthologue of yeast PEX1, a gene required for peroxisomal matrix protein import, and showed that mutations in it are the most common cause of the peroxisome biogenesis disorders.[2](https://doi.org/10.1038/ng1297-445) Complementation group 1 accounted for 51% of all PBD patients at the time, and expressing human PEX1 restored peroxisomal protein import in fibroblasts from 30 group 1 patients.[2](https://doi.org/10.1038/ng1297-445) The paper also reported the common PEX1 allele G843D, present in approximately half of group 1 patients and deleterious to PEX1 activity.[2](https://doi.org/10.1038/ng1297-445)
## Gene discovery in peroxisome biogenesis disorders
Peroxisome biogenesis disorders (PBDs) are autosomal recessive diseases caused by defects in the import of peroxisomal matrix proteins; they include [Zellweger syndrome](https://www.edgepedia.org/zellweger-syndrome), neonatal adrenoleukodystrophy, and infantile Refsum disease.[8](https://pubmed.ncbi.nlm.nih.gov/10904262/) By 2000 the PEX genes mutated in 11 of the 12 known complementation groups had been identified.[8](https://pubmed.ncbi.nlm.nih.gov/10904262/) Gould's laboratory contributed several of the central identifications in 1997.
The December 1997 Nature Genetics paper on PEX1 identified the human orthologue of yeast PEX1, a gene required for peroxisomal matrix protein import, and showed that mutations in it are the most common cause of PBDs.[2](https://doi.org/10.1038/ng1297-445) Complementation group 1 accounted for 51% of all PBD patients at the time, and expressing human PEX1 restored peroxisomal protein import in fibroblasts from 30 group 1 patients.[2](https://doi.org/10.1038/ng1297-445) A common allele, G843D, is present in approximately half of group 1 patients and has a deleterious effect on PEX1 activity.[2](https://doi.org/10.1038/ng1297-445) According to NCBI Gene, PEX1 encodes an AAA ATPase that forms a complex at the peroxisomal membrane and functions in protein import.[9](https://www.ncbi.nlm.nih.gov/gene/5189)
A second 1997 Nature Genetics paper isolated the human PEX12 gene, mutated in complementation group 3.[3](https://doi.org/10.1038/ng0497-385) A 1998 American Journal of Human Genetics study with Gould as corresponding author showed that all group 3 patients carry mutations on both alleles of PEX12, and that loss of PEX12 function produces more severe cellular and clinical phenotypes.[10](https://doi.org/10.1086/302103) That study also described an unexpectedly mild patient whose early truncating mutation allowed translation to restart at a downstream AUG codon, producing a shorter functional protein, and proposed that internal initiation can modulate disease severity.[10](https://doi.org/10.1086/302103)
The third 1997 paper identified PAHX (phytanoyl-CoA alpha-hydroxylase) as the gene defective in Refsum disease.[4](https://europepmc.org/article/MED/9326939) Human PAHX is targeted to peroxisomes by the PTS2 receptor and has phytanoyl-CoA alpha-hydroxylase activity requiring iron and 2-oxoglutarate; both Refsum patients examined were homozygous for inactivating PAHX mutations.[4](https://europepmc.org/article/MED/9326939) A companion paper that year purified the enzyme from rat-liver peroxisomes, found a protein of about 270 amino acids with a cleavable PTS2 signal, and confirmed distinct inactivating mutations in four or so Refsum patients.[11](https://europepmc.org/article/MED/9326940)
Gould synthesized this era in two 2000 reviews: the Annual Review of Genetics article on the genetics of peroxisome biogenesis, and a Trends in Genetics review of PBD genetics and cell biology.[12](https://www.annualreviews.org/content/journals/10.1146/annurev.genet.34.1.623) • [8](https://pubmed.ncbi.nlm.nih.gov/10904262/)
## Clinical impact
The gene discoveries translated directly into molecular diagnosis. GeneReviews-level clinical data attribute about half of Zellweger spectrum disorder cases to PEX1 pathogenic variants, roughly 10% to PEX6, and about 6% to PEX12.[13](https://ncbi.nlm.nih.gov/books/NBK1448/) A separate study found that patient fibroblasts carrying G843D grown at 30 °C showed a two- to threefold increase in PEX1 protein with recovery of peroxisomal function, consistent with a misfolded protein stabilized at lower temperature.[14](https://pmc.ncbi.nlm.nih.gov/articles/PMC1226046/) Incidence estimates have moved with better data: GeneReviews records a former estimate of 1:50,000 births from a 2001 Gould paper, revised to a confirmed 1:133,000 in New York state newborn screening.[13](https://ncbi.nlm.nih.gov/books/NBK1448/)
## Current research program
The Gould laboratory has moved from peroxisomes to the exosome biogenesis pathway. Its stated areas are the molecular mechanisms of exosome biogenesis; engineered exosome-based tools, vaccines, and therapeutics; expression-dependent strategies to reverse pathogenic cell phenotypes in chronic pain and other diseases; and tools for selecting transgenic mammalian cells.[5](https://cellbio.jhmi.edu/people/stephen-gould-ph-d/) The laboratory also examines how HIV and other retroviruses use the exosome biogenesis pathway to form infectious virions, and the consequences of that origin.[15](https://www.hopkinsmedicine.org/research/labs/s/stephen-gould-laboratory)
## Funding and service
The 1997 PEX1 work was supported by NIDDK and the Eunice Kennedy Shriver NICHD.[2](https://doi.org/10.1038/ng1297-445) He founded the American Society for Exosomes and Microvesicles, is a founding board member of the American Association for Extracellular Vesicles, and is editor of exosome.org; for 14 years he organized the annual meeting of US exosome scientists and developed the first graduate-level exosome class.[1](https://profiles.hopkinsmedicine.org/provider/stephen-j-gould/2777555)
## References
1. Stephen J. Gould, PhD, Johns Hopkins Medicine Profiles. https://profiles.hopkinsmedicine.org/provider/stephen-j-gould/2777555
2. Mutations in PEX1 are the most common cause of peroxisome biogenesis disorders. Nat Genet 1997. https://doi.org/10.1038/ng1297-445
3. Isolation of the human PEX12 gene, mutated in group 3 of the peroxisome biogenesis disorders. Nat Genet 1997. https://doi.org/10.1038/ng0497-385
4. Identification of PAHX, a Refsum disease gene. Nat Genet 1997. https://europepmc.org/article/MED/9326939
5. Stephen Gould, Ph.D., Johns Hopkins Cell Biology. https://cellbio.jhmi.edu/people/stephen-gould-ph-d/
6. About the PI, Gould Lab. https://sgouldlab.com/team-members/about-pi/
7. Stephen Gould, Johns Hopkins Pure research portal. https://pure.johnshopkins.edu/en/persons/stephen-gould/
8. Peroxisome biogenesis disorders: genetics and cell biology. Trends Genet 2000. https://pubmed.ncbi.nlm.nih.gov/10904262/
9. PEX1, NCBI Gene. https://www.ncbi.nlm.nih.gov/gene/5189
10. Phenotype-genotype relationships in complementation group 3 of the PBDs. Am J Hum Genet 1998. https://doi.org/10.1086/302103
11. Refsum disease is caused by mutations in the phytanoyl-CoA hydroxylase gene. Nat Genet 1997. https://europepmc.org/article/MED/9326940
12. The Genetics of Peroxisome Biogenesis. Annu Rev Genet 2000. https://www.annualreviews.org/content/journals/10.1146/annurev.genet.34.1.623
13. Zellweger Spectrum Disorder, GeneReviews. https://ncbi.nlm.nih.gov/books/NBK1448/
14. Disorders of peroxisome biogenesis due to mutations in PEX1. Am J Hum Genet. https://pmc.ncbi.nlm.nih.gov/articles/PMC1226046/
15. Stephen Gould Laboratory, Johns Hopkins Medicine. https://www.hopkinsmedicine.org/research/labs/s/stephen-gould-laboratory
16. NIH R01 DK059479, Peroxisome Membrane Biogenesis. https://grantome.com/grant/NIH/R01-DK059479-02
17. Stephen Gould, Hopkins BCMB. https://bcmb.bs.jhmi.edu/people/stephen-gould/
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*Topic: Encyclopedia › Life and health › Life and health scientists › Life scientists › Researchers in molecular and cell biology › Autophagy and membrane trafficking › Secretory pathway and organelle biogenesis*
*Initially written Sep 21, 2026 · Reviewed: Sep 25, 2026 · Edited: Sep 25, 2026; Oct 11, 2026 · Last review: Sep 25, 2026*
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License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license