Screening for 22q11.2 and 10p13 Deletion Syndromes Using the Mean Platelet Volume to Platelet Count Ratio

22q11.2 deletion syndrome is associated with DiGeorge syndrome, velo-cardiofacial syndrome and Opitz G/BBB syndrome.

A patient with 10p13 deletion may show features that overlap with DiGeorge syndrome.

Clinical features:

(1) facial dysmorphism

(2) neurodevelopmental delay (mental-motor retardation)

Laboratory features:

(1) mean platelet volume >= 8.6 fL (presence of macrothrombocytes)

(2) platelet count <= 265,000 per µL

(3) MPV to platelet count ratio >= 3.3

MPV to platelet count ratio =

= (mean platelet volume) / ((platelet count per µL) / (10^5))

If multiple findings are present, then the patient should be tested for 22q11.2 deletion by FISH analysis.

If there are no macrothrombocytes (MPV normal), then test for the 10p13 deletion.