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Adding the Gene to Geneograms
Edwin M. Knights describes one of the newer methods of recording family data.

"The first family records were likely recorded on cave walls, but record keeping has become more sophisticated since that time."

WRITTEN DOCUMENTATION of family history started back in the days when cave-dwellers began to decorate their walls with pictographic petroglyphs portraying peripetia. Later, the nobility and wealthy families could commission portrait painters or even sculptors to document their importance for posterity. Clever artists usually succeeded in giving at least a hint of the underlying personalities of their subjects, but they risked dismissal, banishment from the realm, or no doubt even worse fates. Even the talented Gilbert Stuart managed to bungle a painting of Commodore Bainbridge, giving him a shape best described as a truncated ostrich. A subsequent unknown artist modified Stuart's work with a more flattering physique to complement the handsome face that Stuart had portrayed.
        Having one's statue displayed prominently has always invited attacks by unimpressed detractors, as the political winds swirl in different directions. President Andrew Jackson, who was also Commander-in-Chief, thought it fitting to have his bust carved as the figurehead of America's icon sailing ship, Old Ironsides. When the warship returned to its home port of Boston, it was not greeted with the usual enthusiasm. In those days, before the reign of Kennedys, the city was a Republican stronghold and they did not appreciate their favorite frigate being transformed into a floating advertisement for the incumbent President. One stormy summer night the figurehead was decapitated by an irate Bostonian wielding a sharp saw. Fortunately for Jackson, wooden heads could be cloned.
        Written family records cover but a brief portion of humanity's existence. Prince Charles is said to have 262,142 recorded ancestors, but even this impressive genealogical record includes only the last 1,500 years. The 19th century seems to be the dawn of genealogy for those not primarily concerned with royal lineage, as a new breed of genealogists emerged, gleaning information from oral history, family Bibles and town records. Many family trees began to sprout, illustrated with carefully crafted charts. Folklore and tradition tended to diminish in importance as genealogists focused on the importance of primary documentation of evidence. In recent years, however, more attention has been paid to recording more than just the vital statistics. McGoldrick and Gerson probably can be credited with introducing the term "genogram" in 1985, but similar charts were in common use to track family medical histories well before then.

"A geneogram of the Kennedy family."

Pedigree Patterns
In 1975, Dr. Victor A. McKusick emphasized the importance of a thorough family history in the evaluation of genetic disorders, especially of the first-degree relatives (i.e., parents, siblings and offspring). He divided genetic diseases into three groups:
        1. Chromosomal disorders, involving the lack, excess, or abnormal arrangement of one or more chromosomes.
        2. Mendelian, or simply inherited disorders, determined primarily by a single mutant gene. These can be autosomal dominant or recessive, or they can be X-linked types.
        3. Multifactorial disorders. These are caused by an interaction of multiple genes and multiple exogenous or environmental factors. Although these appear to run in families, the inheritance pattern is complex and the risk to relatives is much less than the Mendelian type.
        McKusick created charts of these three varieties of disorders and noted differing pedigree patterns which helped to distinguish them. They are really little family trees, or saplings, ideally involving four generations.
        1. An autosomal dominant pedigree (single mutant gene) shows: a) Each affected person has an affected parent (unless it's a new mutation); b) An affected person has equal numbers of normal and affected offspring; c) Normal children of an affected person have only normal offspring; d) Males and females are equally affected; e) Each sex is likely able to transmit the condition to male and female offspring; and f) The chart shows a vertical transmission pattern through successive generations.
        2. An autosomal recessive pedigree shows: a) Parents are clinically normal; b) Only siblings are affected; c) Vertical transmission does not occur; and d) Males and females are affected equally.
        3. McKusick also created charts showing X-linked dominant and recessive patterns and described patterns associated with more complicated multifactorial genetic diseases. In the latter there is a cumulative effect of inheriting just the right combination of genes to produce the clinical symptoms.
        By using these genograms it's possible to predict the genetic risk within a family.

"Pedigrees and genograms can be made even more useful when employed in combination with DNA analysis."

A New Tool: DNA
Pedigree patterns and genograms assume new importance when combined with the information becoming increasingly available from DNA analysis. Both symptomatic and asymptomatic family members can be checked for the presence of atypical genes, making the inheritance pattern immediately clear. For this reason it is important to PRESERVE DNA EVIDENCE FROM THE OLDER GENERATIONS - evidence usually lost forever when these individuals die. DNA collections are now easily developed from living family members. They can be stored in refrigerated banks established for this purpose. Or lyophilized DNA can be stored at home in contamination-proof containers without the need for refrigeration. Fingertip blood provides the best samples from living persons. It is also possible to save DNA from recently deceased relatives in the funeral home; post-mortem blood is no longer a good source for the DNA but buccal (inside the cheek) biopsies can be collected easily and the preservation process is the same. Of course the value of this DNA record is not limited to currently-recognized genetic diseases, as we are finding more and more conditions with DNA-related factors or susceptibilities. DNA knowledge not only enlightens us about our past - it has become a powerful tool to improve future family health.

Further Reading

  • Gerson, R. and M. McGoldrick. Genograms in Family Assessment (New York: WW Norton & Co., 1985).
  • Goldstein, J.L. and M.S. Brown. "Genetic Aspects of Human Disease" in Principles of Internal Medicine Ed. 8, Thorn G et al., eds. (New York: McGraw-Hill, 1977).
  • Knights, E.M. "Partners in Progress: Genealogy and Molecular Genetics" in NEXUS, Vol. 13, No. 6 (Boston: NEHGS, 1996).
  • Marlin, E. Genograms (Chicago: Contemporary Books, 1989).

This article originally appeared in our January/February 2002 issue.


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