How to Draw a Pedigree

Before you begin

First name or initials of relatives (To maintain confidentiality do NOT use full names; alternatively, use generation-individual numbers (I-1, I-2, II-1). Please limit identifying information to be compliant with HIPAA guidelines.)
Affected status (i.e. who in the family has disease) for each individual in the family.
Age of all family members, or age at death (To be compliant with HIPAA guidelines, please do not submit a full birth date at this time.).
Whether individuals are living or deceased. Cause of death, if known, should be indicated below the symbol.
Residence for all family members (City, State).
Willingness to participate in the study (indicate with an asterisk).
Key to shading of symbols.
Adoption status
Consanguinity (i.e. parents are related)
Race and ethnicity
Date pedigree obtained

It is helpful to start in the middle of the page when drawing a pedigree.
Male partners are to the left of female partners.
Siblings are drawn from oldest to youngest with the oldest listed on the left and the youngest on the right.
If there are multiple disorders or diseases, use quadrants or different shading (solid, cross-hatching) to indicate each disease (see examples)

Step 1 - Where to begin

a. Draw the proband

Begin by drawing a solid square (male) or circle (female) for the first person with disease who presented to medical attention. This individual is called the proband. Place an arrow on the lower left corner of this individual to indicate he/she is the proband.

c. Proband labeling

Add the age

Write the person's current age below the symbol.

b. Label the proband

Add the initials

Write the person's first name, or initials below the symbol.

d. Proband labeling

Add the disease or disorder

Indicate the disease or disorder the individual has along with the age of onset below the symbol.

Step 2a

Add parents

Next, draw the person’s parents. To indicate partners/marriage draw a horizontal line connecting the two symbols (see below). If the individuals are consanguineous (i.e. related) indicate consanguinity with a double horizontal line. If the degree of consanguinity is not clear on the pedigree, please write above the relationship line, i.e. “2nd cousins.”

Step 2b

Label parents

Add the parents current age, or age at death (d. age or year) with cause of death. Also, indicate any diagnoses (dx. Disease X) the individuals may have along with the age at diagnosis (dx. Disease X 50y.o.).

Step 3

Add siblings

Draw any siblings in birth order from left (oldest) to right (youngest). Siblings are connected by a horizontal line above the symbols, with vertical lines connecting the symbols to the horizontal line. Leave space to add any partners and children.

Step 4

Add other relatives (e.g., grandparents, aunts, uncles)

Add aunts, uncles, grandparents in the same manner. All affected individuals should be included in the pedigree and as many unaffected individuals as possible (parents, grandparents, and siblings of any affected individual).

Step 5

Label siblings and other relatives

For each individual add the following below their symbol;

Initials or generation number.
Current age (if known).
Any diagnoses the individual has received along with the age of onset of the disorder.

If working with a research study:

An asterisk (*) next to individuals willing to participate in the study.
The current place of residence (City, State) for each individual willing to participate in the study can be recorded on the pedigree.

Step 6

Label pedigree - finishing touches

At the top of the pedigree write the ethnicity of each grandparent. Record the date the pedigree was obtained.
Finally, draw a key in the lower left corner indicating what the shading represents.

Glossery of symbols and lines

Living unaffected female: Clear circle	Living unaffected male: Clear square	Unknown sex: Clear diamond
Living affected female: Black circle	Living affected male: Black square
Marriage/Mating Line: horizontal line connecting 2 symbols at the center of each symbol
Separated, Divorce, Relationship no longer exists Line: horizontal line connecting 2 symbols with 2 diagonal hash marks
Offspring Line: Vertical line from the center of the mating line to the center of the offspring symbol or to the sibling line
Children from a previous partner (stepchildren)
Sibling line
Horizontal line above the offspring and connected by vertical lines.		Example: brother and sister siblings (single births)
Dizygotic (fraternal) twins indicated by two diagonal vertical lines originating from the same point
Monozygotic twins have a horizontal line connecting the diagonal lines
No children A vertical line with 2 hash marks at the end. Indicate if an adult does not have children by choice (c), infertility (i)

Use a diamond if the gender is not yet known, a circle or a square if the gender is known.
A triangle is used for any pregnancy not carried to term.
Include gestational age, or estimated date of delivery (EDD) for all pregnancies.
Pregnancy (P), Stillbirth (SB), Spontaneous abortion (SAB), Termination of pregnancy (TOP), Ectopic pregnancy (ECT).

Place brackets around the adopted individual. A dashed offspring line indicates the individual was adopted into the family, and a solid line indicates the individual was adopted out of the family.

Iowa Institute of Human Genetics

How to Draw a Pedigree

Before you begin

Step 1 - Where to begin

a. Draw the proband

c. Proband labeling

b. Label the proband

d. Proband labeling

Step 2a

Step 2b

Step 3

Step 4

Step 5

Step 6

Glossery of symbols and lines

Sibling line

No children

References

How to Draw a Pedigree

Before you begin

The following information must be included on the pedigree:

General guidelines

Glossery of symbols and lines