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CION Cancer Clinics
Reading your pedigree: what the symbols mean | CION Cancer Clinics
A pedigree is your family tree drawn in standard symbols. Squares are men, circles are women, shading marks who had cancer and a slash means a relative has died. Knowing these few symbols lets you check your own drawing for mistakes. This page walks through each symbol, how to read the drawing step by step, and when to ask your counsellor. At CION Cancer Clinics in Hyderabad, our oncologists review your family history with you and guide you to the right genetic counselling and testing.
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Medically reviewed by Dr. Naresh GunduConsultant Medical Oncologist · MBBS, DNB (Internal Medicine), DM (Medical Oncology, AIIMS) · last reviewed September 2026, next review due September 2027
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On this page
- What is a pedigree, and why should I learn to read mine?
- What do the shapes, shading and lines mean?
- How do I read my own pedigree, step by step?
- The words written on a pedigree, in plain language
- What you might see, and what it means
- What this page cannot tell you
- Four things families assume about the pedigree
- Common questions about reading a pedigree
The short answer
What is a pedigree, and why should I learn to read mine?
A pedigree is your family tree drawn in a standard set of symbols. Each shape is a person, each line is a relationship, and shading marks who had cancer. Once you know a handful of symbols, you can read your own and check it is right.
Why checking it yourself matters
The counsellor builds the drawing from what you tell them in one sitting. Names get confused, a cousin is put on the wrong side, or an aunt is missed. Every risk estimate and test decision rests on that drawing. Reading it lets you catch a mistake before it shapes advice for the whole family.
How the drawing is laid out
Each generation sits on its own row. The oldest generation is at the top, usually your grandparents, and the youngest is at the bottom. Rows are often labelled with Roman numerals, and people in each row are numbered from left to right. That way anyone can point to one person without writing a name.
Ask for a copy of your pedigree. You are entitled to see how your family has been recorded.The basic symbols
What do the shapes, shading and lines mean?
Most counsellors follow the same international standard, so a pedigree drawn in Hyderabad can be read by a counsellor anywhere.
Squares and circles
A square is a male relative and a circle is a female relative. A diamond is used when the sex is not stated, or for a group of siblings drawn as one symbol.
Shading
A filled symbol means that person had the condition being studied, here usually cancer. A key beside the drawing says what each shading means.
- Fully shaded: one cancer
- Split into quarters: more than one cancer
- A dot inside: a carrier who is well
Lines between people
A horizontal line joins partners. A vertical line drops from that line to their children, who hang from a bar in birth order, oldest on the left. A double line joins partners who are blood relatives.
Marks on a symbol
A diagonal slash through a symbol means that person has died. An arrow points to the person who first brought the family to the clinic.
- Text below: cancer type and age at diagnosis
- A plus or minus: tested positive or negative
- A question mark: details not confirmed
Not sure whether this applies to you?
Ask an oncologistReading it yourself
How do I read my own pedigree, step by step?
Find the arrow
Start with the person the arrow points to. That is usually you, or the relative who has cancer. Everything else is read in relation to them.
Check your own row
Count your brothers and sisters. Check each one is the right sex, in the right order, and marked correctly as well or unwell.
Move up to parents and grandparents
Your mother's side and your father's side should sit on opposite sides of the drawing. Check nobody has crossed over.
Read the notes under each shaded symbol
Look at the cancer type and the age at diagnosis. A wrong age or a wrong organ is the most common error, and it matters most.
Look for the pattern on each side
Several shaded symbols on one side, young ages or rare cancers are what the counsellor is looking for. Ask what they see.
Beside the drawing
The words written on a pedigree, in plain language
- Pedigree
- The family tree drawn in standard symbols. Counsellors usually cover at least three generations.
- Proband
- The first person in the family to be seen by the genetics service, often the one with cancer. Marked with an arrow.
- Consultand
- The person asking for advice, who may be well. Sometimes this is you, while the proband is a parent.
- Affected
- Had the condition being studied. On a cancer pedigree it means that person was diagnosed with cancer.
- Consanguinity
- Partners who are blood relatives, such as cousins or an uncle and niece. Shown with a double line.
- Key
- The small box explaining what each shading or colour means on your particular drawing.
Leave a number, we will call you
One field. No form to fill in, and no charge for the call.
Side by side
What you might see, and what it means
On the drawing
What it tells you
A shaded circle with a slash through it
A woman who had cancer and has since died
A double line between two partners
The couple are related by blood, such as cousins
A diamond with a number inside
Several siblings drawn as one, none affected
A symbol with a plus sign beside it
That person was tested and carries the family fault
Being straight with you
What this page cannot tell you
It cannot tell you what your pedigree means for your risk. Reading the symbols is one skill. Weighing the pattern, the ages and the gaps is another, and it belongs to the counsellor. What your specific drawing means is a question for the counsellor who drew it.
Drawings differ slightly between clinics
The standard is widely used, but counsellors add their own notes and shading keys. Always read the key on your own drawing first. If a symbol is unclear, ask.
Where Indian families need extra care
Marriages between relatives are common in parts of Telangana and Andhra Pradesh. That makes some drawings loop back on themselves, and relatives can appear on both sides. Tell the counsellor plainly if your parents are related. It changes how the tree is read.
Who this does not apply to
Most people with one older relative who had cancer do not need a detailed pedigree. A simple family history taken by your doctor is often enough to show testing is not needed.
Commonly believed
Four things families assume about the pedigree
"Only relatives who had cancer need to be drawn."
Well relatives matter just as much. A mother with five healthy sisters tells a different story from a mother with one sister who had cancer.
"In-laws and men can be left off."
Men carry and pass on faults exactly as women do. A father's side with few women can hide a pattern that only shows when the men are drawn in.
"Lots of shading means the family definitely has a gene fault."
Common cancers can cluster by chance or through shared habits. The counsellor looks at the type of cancer and the age, not just the number of shaded shapes.
"Once it is drawn, it cannot be changed."
A pedigree is updated whenever you learn something new. A fresh diagnosis or a corrected age should always be passed on to your counsellor.
Questions we are asked
Common questions about reading a pedigree
Can I ask for a copy of my pedigree?
Yes. It is part of your record, and most counsellors are happy to share it. A copy helps you check it at home with older relatives, who often remember details you do not.
What if I spot a mistake on my drawing?
Tell your counsellor as soon as you can, even after testing. A wrong cancer type or age can change the advice given to you and to relatives. The drawing is updated and the risk estimate is looked at again.
Why is my father's side drawn when my mother had cancer?
Because a fault can come from either parent. The counsellor needs both sides to judge where a pattern is, and whether there is one at all. A fault from your father's side works in exactly the same way.
How are adopted relatives shown?
An adopted person is usually drawn with square brackets around their symbol. A line shows whether they were adopted in or out. This matters because adopted relatives do not share the same inherited risk as blood relatives.
How are twins drawn?
Twins hang from a single point instead of two separate lines. Identical twins have a short bar joining their two lines. Identical twins share the same genes, so a result in one usually applies to the other.
What does a question mark next to a relative mean?
The detail has not been confirmed. You may have been told it was cancer without knowing the type, or the age is a guess. The counsellor may ask you to find records to confirm it before weighing that relative fully.
Why does the counsellor want to know if my parents are related?
When parents are blood relatives, they are more likely to share the same rare gene change. This matters more for some inherited conditions than others. It is a medical question, asked without judgement, and it is recorded with a double line.
Can I draw my family tree before the appointment?
A written list helps more than a drawing. Note each relative on both sides, whether they had cancer, what type, and roughly how old they were. Call the CION helpline if you are unsure what to bring.
Your Specialists
Meet CION's oncologists. Bring your family history or genetic report to them.
Our medical oncologists see people with a strong family history of cancer, arrange genetic counselling and testing where it fits, and plan the checks that follow.
Medical Oncologist
Dr. C. Raghavendra Reddy
MBBS(Gold Medal), DNB(General Medicine), DM(Medical Oncology)(Gold Medal)
Medical Oncologist
Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
Medical Oncologist
Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
Medical Oncologist
Medical Oncologist
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Sources
- National Cancer Institute — Cancer Genetics Risk Assessment and Counseling (PDQ)–Health Professional Version
- MedlinePlus Genetics — Why is it important to know my family health history?
- Cancer Research UK — What happens when you see a genetic counsellor
- National Cancer Institute — Genetic Testing for Inherited Cancer Susceptibility Syndromes
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Drawing the pedigree: your family tree on paperHow the counsellor builds the drawing in the first placeVerifying family cancer history with recordsHow to turn a question mark into a confirmed detailRisk assessment: how your number is calculatedWhat the counsellor does with the drawing nextWhat to bring to your first appointmentThe family details worth gathering beforehand
Talk to us
Want someone to walk you through your family tree?
A genetic counsellor can go through your pedigree with you and correct anything that looks wrong. One helpline serves every CION centre.