[An infant with an asymmetric mouth when crying or laughing].

BACKGROUND: If a child cries with an asymmetrical mouth it can be a sign of a nerve compression or a developmental defect in a facial muscle. In the latter case, a 22q11 deletion can be the cause, and multiple organs might be involved. CASE DESCRIPTION: A 2-month-old infant was referred to the paediatric outpatient clinic because he had an asymmetrical mouth when crying or laughing. There were no further symptoms. Genetic investigations and ultrasounds of the heart and kidneys were performed to exclude an underlying syndrome caused by a 22q11 deletion. These revealed no significant findings. It appeared to be a case of isolated 'asymmetric crying facies' as a result of hypoplasia of the depressor anguli oris muscle. CONCLUSION: An asymmetrical mouth in an infant can be a part of a genetic syndrome, in which there can be anomalies in multiple organ systems. For this reason, additional investigations are essential in cases of 'asymmetric crying facies'.