Recording Genetic Information Concerning Individuals and Families

THE notes which follow are intended to form a convenient source of reference for clinicians and o.hers who encounter individuals and families with interesting variations and traits. As specific abnormal traits are usually uncommon and are seldom encountered, the individual clinician may have to spend much time searching for guidance on what information he should collect which may be relevant to the genetical interpretation of his observations. The basic mechanisms of elementary genetics are readily understood and accounts may be found in any textbook. However, in man, where families are small, generations alive at one time few, and experiment impossible, the recognition of a genetic mechanism may be very difficult. It follows that increases in genetic knowledge from clinical and famnily pattern studies will usually come from descriptions and data from many sources. Such descriptions and such data must therefore be as accurate and as detailed as possible if the maximum contribution to knowledge is to be made. Not infrequently reports of genetic interest omit many simple facts about the patient or family which are readily available, but were either not elicited or not recorded because their importance was not realized. Usually the intention of the recorders is to look for evidence xvhich wvill enable the type of inheritance to be recognised. In essence this involves comparison of the observed pattern of a trait in a family or families with that to be expected on various theoretical hypotheses. If there are gaps in recorded information about affected and, equally important, unaffected members of the families the observed patterns wvill be distorted and misleading. In brief, the following information is required about the person whose condition initiated the family study (the "Propositus" or "Index Case" or "Proband") and about each of his relatives living and dead.