KomuraSoft LLC
Chapter 6

Genetic testing and family history

Five questions to organize family history, screening vs. diagnosis, VUS, and how to read a negative result.

Words used in this chapter

Family history (family health history)
A record of diseases and health conditions seen in the family.
Screening
A test for broadly picking out candidates for further investigation.
Diagnosis
Confirming or narrowing down whether a suspected condition is present.
Positive
The change being tested for was found.
Negative
No cause was found within the range tested.
VUS (variant of uncertain significance)
A variant whose pathogenic significance is unknown. Its interpretation has not yet been confirmed.
Genetic counseling
A consultation in which family history and test results are organized and explained.

Viewpoint used in this chapter

Of the five viewpoints listed on the course top page, this chapter focuses on "5. Weigh results differently." We practice reading positive, negative, and VUS results with their proper weights, rather than treating them as interchangeable answers.

A test can add answers — and sometimes add questions

Genetic tests are powerful, but the result is not always a simple "yes / no." Positive, negative, and VUS each mean different things.

That is why a test result has to be read together with the person's symptoms, the family history, and what the test actually looked at. It is important not to jump to a conclusion from numbers or labels alone.

Family history is more than genetics, but it is still a strong clue

A family history includes who had which disease, around what age they were diagnosed, which side of the family it was on, and whether test results already exist.

A family history captures not only genetic background but also shared lifestyle and environment. Even so, it is a very important clue at the entry point of clinical care or genetic counseling.

One-line family history notes (hands-on exercise)

This is a hands-on section. Before moving to the comprehension check below, try once to write this out on paper or in a notes app — that drives the framework of relationship / condition / age / side-of-family into your head. Before a consultation, lining up "who / what / around what age / which side of the family" is a useful preparatory exercise. Just putting these four items on one line makes gaps in the information obvious.

Relationship
e.g. maternal uncle.
Condition / symptom
e.g. breast cancer.
Age at diagnosis
e.g. 42.
Side of family / prior testing
e.g. maternal / no prior test.

Example one-line note: "Maternal uncle / breast cancer / age 42 / maternal side / no prior test." Lining up one line per family member is enough as an entry point to family history.

Screening and diagnosis play different roles

Screening is often used to cast a wide net and pick out "candidates to look at more closely." Diagnosis is used to confirm or narrow down a suspected condition.

Both matter, but because their purposes differ, their results are not read the same way. First confirm whether the test is "for finding" or "for confirming."

Positive, negative, and VUS mean different things

Positive
The change being tested for was found. What that means from there depends on the context.
Negative
No cause was found within the range tested. This is not proof that there are no genetic factors at all.
VUS
A variant whose relationship to disease is not yet clear. It cannot be called pathogenic or benign on its own.

In particular, a VUS is itself a result that says "we do not know". It is not a failed test, and it is not a confirmed diagnosis.

Common misunderstandings

  • Negative does not mean "genetic contribution is zero."
  • VUS is not the same as a confirmed diagnosis — its interpretation has simply not been confirmed yet.
  • A family history is not only a record of genetics; it also captures shared environment.
  • Screening and diagnosis are easier to understand as different roles rather than as different tests.

Chapter check — reading tests and family history

Five questions to confirm how to interpret test results and a family history.

Q30. Which is the closest description of a family health history?

Q31. At an introductory level, which is the closest description of the difference between screening and diagnosis?

Q32. Which is the closest description of a VUS (variant of uncertain significance)?

Q33. What is the closest interpretation of a negative result on a genetic test?

Q34. Which of the following is not an example of information that is typically useful to organize before genetic counseling or a clinic visit?

Key takeaways from this chapter

  • A family history is a record that includes genetics, lifestyle, and environment.
  • Screening casts a wide net; diagnosis confirms or narrows down.
  • A VUS is a result whose meaning has not been confirmed at this time.
  • A negative result is read as "no cause was found within the range tested."
  • Before a consultation, organizing relationship, diagnosis, age, and maternal/paternal side goes a long way.