Our Staff

All our professionals at Gastroenterology & Hepatology Associates of Mid-Michigan maintain the highest levels of accreditation and pursue ongoing education to stay abreast of the latest trends in gastroenterology.

Todd K. Holtz, M.D.

Todd K. Holtz, M.D.

Dr. Holtz is a graduate of Wayne State University School of Medicine in 1988. He completed his residency at the University of Michigan Hospital in 1991. He completed his fellowship training at Wayne State University Hospital in 1993. He is board certified in Gastroenterology. Dr. Holtz joined Gastroenterology & Hepatology Associates in 1994.

Ernest Ofori-Darko, M.D.

Ernest Ofori-Darko, M.D.

Dr. Ofori-Darko graduated from the University of Ghana Medical School in 1987. He received his PhD from Harvard Medical School in 1994. He completed his residency at the University of Connecticut in 1997. In 2000 he completed his Fellowship training at the University of Michigan. He is board certified in Gastroenterology. Dr. Ofori-Darko joined the practice in 2000.

Christina L. Murphy, D.O.

Christina L. Murphy, D.O.

Dr. Murphy graduated from Kirksville College of Osteopathic Medicine in 1998. She completed her Internal Medicine residency at Genesys Regional Medical Center. In 2004 she completed her Gastroenterology Fellowship at Genesys Regional Medical Center. She is board certified in Gastroenterology. Dr. Murphy joined the practice in 2004.

Karen F. Huang, D.O.

Karen F. Huang, D.O.

Dr. Huang graduated from Michigan State University College of Osteopathic Medicine in 2002. She completed her Internal Medicine residency at Genesys Regional Medical Center in 2005. In 2008 she completed her Fellowship in Gastroenterology at Genesys Regional Medical Center. She is board certified in Gastroenterology. Dr. Huang joined Gastroenterology & Hepatology in 2010.

Leann M. Schwedler, MSN, NP-C

Leann M. Schwedler, MSN, NP-C

Leann graduated from Saginaw Valley State University, University Center, Michigan in 2014 with a Master of Science in Nursing, Family Nurse Practitioner. She was certified through the American Nurses Credentialing Center Nurse Practitioner in 2015. Leann joined the practice in 2015.

Susan M. Knoerr, DNP, FNP-C

Susan M. Knoerr, DNP, FNP-C

Susan graduated from Saginaw Valley State University, University Center, MI in 2007 with her Bachelor of Science in Nursing. She graduated from the University of Michigan, Flint in 2014 with her Doctor of Nursing Practice, Family Nurse Practitioner degree. She is certified with AANP. Susan joined the practice in 2017.