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6 Yours, Mine, and Ours—The Blended Family
The most common pedigree symbols. Pregnancy-related symbols are shown in Figure 3.5.
YOURS, MINE, AND OURS—THE BLENDED FAMILY
Pedigree symbols related to pregnancy.
sibling group on the pedigree, ask if they share the same mother and father. If the
answer is no, ask “Which of your brothers and sisters share the same mother and which
share the same father?” Not uncommonly patients confuse half-sibs from step-sibs.
If there is a big gap in age between siblings, this is a clue that they may be
half-siblings. The gap may also be an indication of a period of infertility.
It is not necessary to include each partner of an individual on a pedigree—doing so
can make a pedigree quite complicated as is illustrated in actress Elizabeth Taylor’s
marriage history shown in Figure 3.6.
Figure 3.6 A pedigree of actress Elizabeth Taylor demonstrating how to illustrate multiple marriage partners, step-children, and half siblings. (Source:
3.7 PEDIGREE SYMBOLS RELATED TO PREGNANCY
The various pedigree symbols related to pregnancy, spontaneous abortion, termination
of pregnancy, stillbirth, and infertility are shown in Figure 3.5. If the gestational age is
known, place the gestational age in weeks (wk.) below the symbol. An approximation
of dates can be shown such as “∼12 wk.” Usually the gestational age is stated as the
date from the ﬁrst date of the last menstrual period (LMP) or the estimated date of
delivery (EDD). The older terminology of estimated date of conﬁnement (EDC) is
considered archaic. Pregnancy dating by ultrasound can be noted as “US 12 wk.”
A stillbirth (SB) is deﬁned as “the birth of a dead child with gestational age noted”
(Bennett et al., 1995).
If the gender of the fetus is known then one can write “male” or “female” under the
symbol. This is preferable to making the symbol a square or a circle. If a chromosome
study has conﬁrmed the sex of the fetus, this can be noted under the symbol as
“46,XX” or “46,XY.”
3.8 ASSISTED REPRODUCTIVE TECHNOLOGIES (ART) AND USE
OF DONOR GAMETES
The importance of recording family history for persons conceived through ART,
including information on the family history of egg or sperm donors is detailed in
Chapter 8. The symbols to use in recording this information are noted in the tables to
Chapter 8. Some birth defects may be related to assisted reproductive technologies
(e.g., in vitro fertilization, frozen embryos), and therefore the method of ART should
be recorded on the pedigree.
It is important to distinguish a person who is adopted in to a family (a nonbiological
relative) from a person who is adopted out (a biological relative). To symbolize
adoption, brackets are placed around the symbol for male (square) or female (circle)
or unknown (diamond). If a person or couple adopts an individual, the individual’s
line is dotted (indicating a nonbiological relationship). A person who is placed for
adoption has a solid individual’s line to the birth parents.
It is not uncommon for a family member to adopt a relative—for example, a sibling
adopting a niece or nephew, or grandparents adopting a grandchild. The method of
recording this situation on a pedigree is shown in Figure 3.7.
When a person or couple adopts a child it is useful to inquire if there was a medical
reason; perhaps an adoptive parent had a genetic condition or the couple who adopted
the child experienced infertility. The reason can be noted below the line of descent.
When a child is placed for adoption, information about the child’s medical heritage
is usually given to the adoptive parents (see Chapter 7). A sample adoptive medicalfamily history form can be found in Appendix A.4.
GETTING TO THE ROOTS: RECORDING THE FAMILY TREE
Pedigree symbolization of adoption.
3.10 INFERTILITY AND NO CHILDREN BY CHOICE
If a person or couple is of reproductive age and has no children, inquire if this is by
choice or for a biological reason. The cause of infertility should be noted below the
individual’s line (e.g., azoospermia, endometriosis, etc.).
3.11 AFFECTED STATUS: SHADING THE PEDIGREE SYMBOLS
Accurately documenting who is affected and unaffected on a pedigree is critical for
pedigree analysis. A symbol should only be shaded if the person, pregnancy, miscarriage, or abortion is clinically affected. Of course, whether a person is considered
affected may be a function of the sensitivity of the clinical tool that is used to deﬁne