A 7-year-old boy has hypernasality and velopharyngeal incompetence. He underwent repair of a ventricular septal defect at birth and repair of a cleft palate at age 9 months. His mother says that he has had difficulties with language learning. Physical examination shows upward slanting of the palpebral fissures, a broad nasal root, a small mouth, and a thin upper lip. Which of the following studies is most likely to lead to a diagnosis in this patient?A. Measurement of serum creatine kinase level
Fluorescent in situ hybridisation (FISH) analysis. This is the classic test to diagnose velocardiofacial syndrome, otherwise known as Di George syndrome, Shprintzen’s syndrome and catch 22 syndrome (chromosome locus 22q11.2; C - cardia, A - abnormal facies, T - thymic aplasia, C - cleft palate, H - hypocalcaemia). Inheritence is usually sporadic.