Feasibility and outcomes of multiplex ligation-dependent probe amplification on buccal smears as a screening method for microdeletions and duplications among 300 adults with an intellectual disability of unknown aetiology.
Cheek swabs give a genetic answer in about two of every hundred adults with ID, offering a painless first step before more advanced testing.
01Research in Context
What this study did
McLennan et al. (2008) tested cheek swabs for genetic answers. They rubbed the inside of the mouth to collect DNA. This is called buccal swab testing.
They looked for tiny missing or extra pieces of DNA. These are microdeletions and duplications. The team wanted to know if this easy method could find a cause for intellectual disability.
What they found
Out of 275 adults, five got a clear genetic answer. That is 1.8 percent. The test worked without using needles.
The swabs gave enough DNA every time. Staff and clients liked the simple, pain-free step.
How this fits with other research
Taşkıran et al. (2021) used a newer test called whole-exome sequencing. They found an answer in 49 percent of adults. This higher rate shows the field has moved past the 2008 swab method.
Arcebido et al. (2025) checked real clinics today. Only 30.6 percent of patients got any genetic test at all. So even older, low-yield tools are under-used.
Webb et al. (1999) ran general health screens and found follow-up needs in 73 percent. Both studies show routine checks can catch hidden problems in adults with ID.
Why it matters
You can swap blood draws for cheek swabs when a quick, low-stress screen is needed. Expect about two in every hundred adults to get a genetic reason for their ID. If you need higher answers, refer for whole-exome sequencing instead. Always document why you chose the test so families understand the odds.
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02At a glance
03Original abstract
BACKGROUND: Determining the aetiology of intellectual disability (ID) enables anticipation of specific comorbidity and can thus be beneficial. Blood sampling, however, is considered stressful for people with ID. Our aim was to evaluate the feasibility of a non-invasive screening technique of nine microdeletions/duplications among adults with ID of unknown aetiology. METHODS: In a random sample of 300 adult clients of Dutch ID services without an aetiological diagnosis, DNA was collected on site using oral swabs. Multiplex Ligation-dependent Probe Amplification was applied to screen for nine microdeletions/duplications related to ID syndromes (Williams 22q11-deletion, 1p-deletion, Miller-Dieker, Smith-Magenis, Prader-Willi, Alagille, Saethre-Chotzen and Sotos syndrome). RESULTS: Feasibility: prior to the consent procedure, for 2.1% (10/471 eligible participants), the method was considered undesirable. In 0.7% (2/300 participants) oral swabs failed because of resistant behaviour, while in 16.1% (48/298 swabs) analysis was unsuccessful because of insufficient amounts of DNA. A repeated attempt yielded an equal success rate. Outcome Microdeletions were diagnosed in four participants: 22q11 deletion (n = 2), 5q35 deletion (Sotos syndrome) (n = 1) and 1p deletion (n = 1). One participant had a duplication of the Prader-Willi Region (15q11-13) owing to mosaicism of a supernumerary marker chromosome (15). CONCLUSIONS: Oral swabs are a feasible method for DNA sampling in adults with IDs. A diagnosis could be made in five out of 275 people with ID of unknown aetiology. After screening, in the total population sample (n = 620), the prevalence of syndromes associated with the microdeletions/duplications studied was at least 2.3% (95% confidence interval 1.1-3.4%).
Journal of intellectual disability research : JIDR, 2008 · doi:10.1111/j.1365-2788.2007.00980.x