Johns Hopkins School of Medicine in the context of "Johns Hopkins University"

Lesch–Nyhan syndrome (LNS) is a rare inherited disorder caused by a deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT). This deficiency occurs due to mutations in the HPRT1 gene located on the X chromosome. LNS affects about 1 in 380,000 live births. The disorder was first recognized and clinically characterized by American medical student Michael Lesch and his mentor, pediatrician William Nyhan, at Johns Hopkins.

The HGPRT deficiency causes a build-up of uric acid in all body fluids. The combination of increased synthesis and decreased utilization of purines leads to high levels of uric acid production. This results in both high levels of uric acid in the blood and urine, associated with severe gout and kidney problems. Neurological signs include poor muscle control and moderate intellectual disability. These complications usually appear in the first year of life. Beginning in the second year of life, a particularly striking feature of LNS is self-mutilating behaviors, characterized by lip and finger biting. Neurological symptoms include facial grimacing, involuntary writhing, and repetitive movements of the arms and legs similar to those seen in Huntington's disease. The cause of the neurological abnormalities remains unknown. Because a lack of HGPRT causes the body to poorly utilize vitamin B₁₂, some males may develop megaloblastic anemia.

Johns Hopkins Hospital (JHH) is the teaching hospital and biomedical research facility of Johns Hopkins School of Medicine in Baltimore, Maryland. Founded in 1889, Johns Hopkins Hospital and its school of medicine are considered to be the founding institutions of modern American medicine and the birthplace of numerous famed medical traditions, including rounds, residents, and house staff. Several medical specialties were founded at the hospital, including neurosurgery by Harvey Cushing and Walter Dandy, cardiac surgery by Alfred Blalock and Vivien Thomas, and child psychiatry by Leo Kanner. Johns Hopkins Children's Center, which serves infants, children, teens, and young adults aged 0–21, is attached to the hospital.

Johns Hopkins Hospital is widely regarded as one of the world's greatest hospitals and medical institutions. For 21 consecutive years from 1991 to 2020, it was ranked as the best overall hospital in the United States by U.S. News & World Report. In its 2019–2020 edition, U.S. News & World Report ranked the hospital on 15 adult specialties and 10 children's specialties; the hospital came in 1st in Maryland and third nationally behind the Mayo Clinic in Rochester, Minnesota and Massachusetts General Hospital in Boston. In 2021, the hospital marked 32 consecutive years of placing in the top five hospitals in the nation.

Michael Lesch (June 30, 1939 – March 19, 2008) was an American physician and medical educator who helped identify an important genetic disorder associated with intellectual disability and self-mutilation. This disease is now known as the Lesch–Nyhan syndrome. In the mid-1960s when the syndrome was discovered, Lesch was a research associate working at the Laboratory of General and Comparative Biochemistry at the NIH National Institute of Mental Health in Bethesda, Maryland. William Nyhan, a pediatrician and biochemical geneticist, was his mentor. Lesch was 30 years old when he discovered the disease.

Lesch completed his medical training at Johns Hopkins in the Osler Medical Service in 1964. While at Hopkins he earned the distinguished honor of president, Alpha Omega Alpha, The Johns Hopkins University Chapter.

William Leo Nyhan (born March 13, 1926) is an American physician best known as the co-discoverer of Lesch–Nyhan syndrome.

Nyhan currently serves as professor of pediatrics at University of California, San Diego School of Medicine in La Jolla, California. He has held positions at Johns Hopkins School of Medicine and the Miller School of Medicine at the University of Miami, and has served on a number of advisory committees, pediatric advisory boards, and research foundation boards.