PTPRQ and myopathy: Although the family history was negative for thumb aplasia, epilepsy, mental retardation, myopathy, and orthopedic disease, the clinical presentation of the index patient was suspected due to a sporadic genetic defect at either the chromosomal or gene level. Chromosomal micro- or macrodeletions or duplications as well as point mutations in PTPRQ, SALL4, RECQL4, and SALL1 have previously been identified in syndromic thumb aplasia.