Genetic testing for a suspected rare disease in a child

Begin with the problem the test should explain

A child may come to genetics because of developmental differences, seizures, unusual growth, congenital anomalies or several symptoms that have not yet formed a clear diagnosis. Similar symptoms can have different causes, so the test should be chosen alongside a careful clinical assessment.

Write a short timeline from pregnancy and birth to the present. Include when skills were acquired or lost, major illnesses and relevant family history. A clear timeline often helps more than sending a large folder without explaining which question remains unanswered.

Sources and references: [1]

Why a smaller test can sometimes be the right one

Genetic investigations can look at an individual gene, a group of genes, chromosomes or other relevant biological changes. When the examination strongly suggests a particular condition, a targeted test may answer the question directly. A panel can be useful when several known genes could explain a recognizable pattern.

Ask what the proposed test detects and what it could miss. A previous negative result only has meaning within the scope of that test. Bring the full laboratory report, including its methods, rather than a message saying that a genetic test was normal.

Sources and references: [1] [3]

What whole exome sequencing adds

Whole exome sequencing examines the protein-coding portions of genes. Whole genome sequencing examines a broader portion of the DNA sequence. Both can help when the clinical picture does not point to a single gene, although neither identifies every possible genetic cause.

ACMG guidance supports considering exome or genome sequencing as a first- or second-tier investigation for children with congenital anomalies, developmental delay or intellectual disability. That recommendation applies to a defined clinical population. It does not mean every child needs broad sequencing or that an exome is always the next test after an uncertain appointment.

Sources and references: [2] [4]

What a result could change

Before testing, ask the team to describe the possible next decisions. A diagnosis may guide further examinations, surveillance, family counselling or treatment choices. In other cases, the most immediate benefit is an explanation that helps organize care and avoid repeating investigations.

Make this concrete: who will interpret the result, which specialist will discuss it with you and how will it reach the clinicians already caring for your child? A report is most useful when there is an appointment to connect the laboratory finding with the child's symptoms.

Sources and references: [3] [5]

Discuss uncertain and additional findings in advance

A variant of uncertain significance is a DNA change whose role in disease is not established. It should not be treated as a confirmed explanation merely because it appears in a report. Family testing may sometimes help clarify a result.

Broader sequencing can also identify information unrelated to the original question. Ask what the laboratory reports, what choices you have about receiving additional findings and whether those choices differ for a child. Our separate guide to uncertain variants focuses on what happens after a VUS result.

Sources and references: [3] [5]

What happens after a negative result

A negative test can leave a genetic condition unresolved because a test may miss relevant changes or current knowledge may not explain them. The next step can be clinical reassessment, a different test or reconsideration of the results later.

Ask what new information would justify reopening the investigation. Updated symptoms or family information may matter. Keep the original report and laboratory details so a future clinician can see exactly what was done; repeating an apparently similar test without that information can waste time and money.

Sources and references: [3]

Prepare the consent and follow-up questions

Before providing a sample, clarify the test's scope, turnaround estimate, cost and whether samples from relatives might be requested. Ask how consent, storage and access to results are handled, particularly when a sample or report crosses borders.

Parents should leave with a contact for questions and a plan for discussing all possible outcomes, including an uncertain result. Decide who in the family needs an explanation and whether an interpreter will be needed. Genetic terminology is easier to absorb when the appointment has time for the implications, not just the name of a variant.

Sources and references: [1] [5]

A rare-disease assessment in Shanghai

Children's Hospital of Fudan University has developed multidisciplinary rare-disease diagnosis services and molecular diagnostic resources. That makes it a relevant enquiry point when a child needs a coordinated assessment rather than an isolated commercial test.

EastMedGo can help organize the developmental timeline, specialist letters and previous laboratory reports for review. We can clarify which clinic should assess the child and which existing records need translation before discussing new testing. Start with the unanswered clinical question and the tests already completed, so the enquiry can focus on a useful next step.

Sources and references: [6]

Common questions