What is the Rule of Two/Too?

The Rule of Too/Two is an easy way to discover possible risks of genetic conditions in your family medical history.

Have you ever heard of the Rule of Two?

No, this isn’t about Star Wars…

What is the Rule of Two/Too?

If you didn’t know about the Rule of Two/Too, you will likely be very surprised to know that there are more than one of these rules!

The Rules of Two is a quick and easy way to figure our if your child's asthma is under good control.

The Rules of Two is a quick and easy way to figure our if your child’s asthma is out of control.

Remember that one now?

What about this other one?

The rule of Two/Too.

Arthur Grix proposed the Rule of Too/Two to make things simple for primary care providers when looking for genetic conditions within a family.
Arthur Grix proposed the Rule of Too/Two to make things simple for primary care providers when looking for genetic conditions within a family.

The Rule of Too/Two can help you figure out if you might have a genetic condition in your family!

After all, filling out your family medical history is pretty easy for most people. Knowing what to do with all of that information, especially how it might translate into a risk for a genetic condition is the tricky part…

“Family health history questions that result in answers using the descriptors “too” or “two”may indicate a genetic condition.”

A Toolkit to Improve Care for Pediatric Patients with Genetic Conditions in Primary Care

And that’s where the Rule of Too/Two comes in!

It reviews many of the red flags for genetic conditions and can help you figure out if you or your kids should undergo any kind of genetic screening.

The Rule of Too/Two includes:

  • being TOO tall as compared to their genetic potential for height
  • being TOO short as compared to their genetic potential for height
  • getting sick at TOO early/TOO young an age – extreme early onset cardiovascular disease, cancer, or renal failure, etc., and developing adult disorders in childhood can be a sign of a genetic cause
  • TOO many people in a family having the same condition
  • having an unusual or extreme presentation of a common condition that is TOO different than usual, like breast cancer in a male family member
  • a family member having TWO different types of tumors
  • a condition in TWO generations of family members
  • a condition that affects TWO people in the family
  • a family member with TWO or more birth defects or congenital anomalies

When you fill out your family health history, if you are using the terms ‘too’ and ‘two’ very often, then you might talk to your health care provider to take a closer look.

“Everyone is eligible for one tumor, one birth defect (ASD, cleft lip, birth mark, etc.).”

Arthur Grix, MD

The Rule of Too/Two is an easy way to discover possible risks of genetic conditions in your family medical history.

There are other genetic risk assessment methods besides the Rule of Too/Two.
There are other genetic risk assessment methods besides the Rule of Too/Two.

Which ever method you use, if you find genetic risks in your family tree, you might want to see a genetic counselor for further evaluation.

More on the Rule of Two/Too

Author: Vincent Iannelli, MD

Vincent Iannelli, MD