By the late 1950s, genetics was becoming increasingly important in the study of disease. The conquest of many infectious and nutritional diseases had made genetic conditions more conspicuous; the genetic consequences of radiation exposure had attracted more attention since the advent of nuclear bombs; work in molecular biology was starting to elucidate the ways in which faulty genes might produce defective cell proteins; there had been great progress in relating chromosomal abnormalities to clinical syndromes, notably the linking of Down syndrome to an extra copy of chromosome 21. And amniocentesis soon made it possible to do pre-natal examinations of a baby's chromosomes. The relative novelty and rapid growth of medical genetics made it difficult for many individual practitioners and medical school faculty to keep up. In 1959, on their regular summer trip to Maine and Nova Scotia, the McKusicks visited the Roscoe B. Jackson Laboratory (JAX) in Bar Harbor--a leading center for mammalian genetic research--and together with John Fuller, assistant director at JAX, conceived the Short Course in Medical Genetics. The purpose of the intensive two-week course was to provide medical school faculty members and other interested professionals with an introduction to the broad area covered by "medical genetics," to provide insight into the development of modern ideas of heredity, and to integrate medical applications with pertinent aspects of experimental mammalian genetics. The teaching staff for the first course, held at Bar Harbor in the summer of 1960, included eight from JHUSM, eleven from JAX, and eight visiting lecturers. The first week was devoted to basic genetics, starting with mitosis and the formation of germ cell, extending through blood groups, biochemical genetics, and cell genetics, and finally working into the statistical aspects of genetic investigations (with emphasis on the pitfalls of family investigations, and the fact that simple recurrence of a disorder within a family was not enough to label it as hereditary). The second week of the course dealt more specifically with individual syndromes and classes of disorders. The subjects ranged from muscular dystrophy, congenital malformations, anemia, and neurological defects to cancer, circulatory disorders, psychiatric conditions, and radiation genetics.
The "Bar Harbor Course" was an immediate success, and has been held every summer since 1960 as a collaborative effort of Johns Hopkins and the Jackson Laboratory. McKusick served as co-director for many decades. Between 1967 and 1977, sessions in odd-numbered years were devoted to mouse genetics, and titled the Short Course in Experimental Mammalian Genetics. After 1979, with the advent of recombinant DNA technology, the two fields converged in many respects, and the course merged its human and animal genetics components. Since its beginning, the Short Course in Medical Genetics been taught by more than 90 faculty from JHU, more than 120 from JAX, and more than 290 from other institutions. Over 5,000 clinical specialists, medical and scientific educators, and even medical school deans have taken the course. Through its "Press Week," the Short Course has also enabled many medical journalists to write more informed stories about advances in genetic medicine.
One of the ongoing challenges as medical genetics evolved and knowledge accumulated was nosology, i.e., classifying the multiple distinct forms of genetic disorders. Such delineation was vital for proper diagnosis and management of individual cases, for genetic counseling, and for determining the basic defect and pathogenic mechanisms of disorders. In 1968, McKusick organized the first of a series of annual conferences entitled "Clinical Delineation of Birth Defects." Participants shared recent research on various genetic disorders, attended case presentations of patients affected with those disorders, and discussed differential diagnosis. Besides fostering education and research, the published proceedings of the conferences gave an academic respectability to the study of rare syndromes and congenital deformities, both of which had been regarded as a form of medical "stamp collecting."
Five years later, in 1973, McKusick collaborated with Hopkins colleague Frank Ruddle to organize the first Human Gene Mapping (HGM) workshop. Eleven of these international meetings were held between 1973 and 1991, and served an important function in the collation of gene map information both published and unpublished. Groups of researchers who worked on particular chromosomes vetted the information accumulated since the previous conference, including abstracts submitted by workshop participants. The workshops also had committees on comparative gene mapping as well as a committee on nomenclature (which attempted to standardize names of genes and gene symbols and establish conventions for indicating the cytogenetic band location of genes).
McKusick often noted that the development of an effective polio vaccine in the mid-1950s was a key factor in the growth of medical genetics: the National Foundation-March of Dimes (MOD), which had funded substantial polio research, shifted its support focus to new areas, particularly birth defects. MOD provided all of the funding for the first 25 sessions of the Bar Harbor Short Course in Medical Genetics, and continues to provide some of the support; it also funded the Clinical Delineation of Birth Defects conferences and the HGM workshops, and published the proceedings from those events.