Dr Horikawa, a paediatric endocrinologist, is the Director of the Endocrinology and Metabolism Division of the Japanese National Centre for Child Health and Development (NCCHD) and has been with the NCCHD since 2002. She is the author of over 300 original, peer-reviewed endocrinology articles (174 English/152 Japanese) and has contributed to 43 book publications. She has served in executive board member positions in several important national and international professional society groups such as Japan Endocrine Society, Asia Pacific Endocrine Society and Growth Hormone Research Society (GRS). She continues to be active in her editorial work and research interests (growth, sex development, and maturation, neuroendocrinology (hypothalamus-pituitary axis), adrenal disorders). In 2016, Dr Horikawa was awarded the Japanese Society of Pediatric Endocrinology Kenji Fujieda award