While he enjoyed his work as an Examiner, developing advanced techniques for DNA extraction from crime scene samples, he soon became increasingly fascinated with the research aspect.

motivated by this new interest, Dr. Yan pursued graduate studies in the Department of Forensic Medicine at China Medical University while continuing his work at the coroner's office.

After completing his Ph.D., he briefly served as a Postdoctoral Associate at University of Turku before moving to the United States to join Dr. Martin M. Matzuk's lab in the Department of Pathology at Baylor College of Medicine in Houston, Texas.

His lab first put forward a novel idea for the development of non-hormonal male contraceptives: “Do not kill, but disable sperm”,[11][12] which led to the discovery of TRIPTONIDE, a natural compound purified from the Chinese herb Tripterygium Wilfordii Hook F. Triptonide acts as a reversible non-hormonal contraceptive agent in mice and monkeys, and established it as a drug candidate for “The Pill” for men.

In the male, motile ciliary beating functions as an agitator to maintain the constant suspension of immotile testicular sperm during their transit through the efferent ductules in men.

[14][15] This work led to a novel concept that efferent ductal obstructions due to motile ciliopathy represent a new cause of male infertility, which has been validated in clinics.

In the female, motile cilia in the oviduct/Fallopian tube are essential for oocyte pickup and, therefore, fertility, but dispensable for embryo and sperm transport, which are mostly achieved through smooth muscle contraction.

Additionally, using a variety of gene knockout/genome editing technologies, his lab discovered many genetic networks that control the most fundamental cellular and molecular events in spermatogenesis, e.g., sperm connecting piece formation,[18] cytoplasmic removal,[19] global shortening of 3’UTRs,[20][21][22] and delayed translation/uncoupling of transcription and translation, and dynamic changes in poly(A) length and non-A contents.

[23] As a young scientist, Dr. Yan was the first to discover mitochondrial genome-encoded small RNAs (mitosRNAs) [24] and endo-siRNAs in the male germline,[25] as well as meiotic sex chromosome inactivation (MSCI)-escaping X-linked miRNAs [26] and elucidated the functions of all during reproduction.

[34][35] He established the first-ever National Center for Male Reproductive Epigenomics,[36] which is funded by an NCTRI P50 grant from the NICHD with a research focus on the molecular mechanism underlying epigenetic inheritance of lifestyle-induced metabolic syndrome in both humans and mice.

Over the past 16 years, he has mentored six junior faculty members, trained 16 postdoctoral fellows, and 27 graduate students, contributing significantly to the development of the next generation of scientists.