[Genetic diagnosis of a case of Smith-Magenis syndrome due to a rare small-scale deletion].

Objective: To report on a case of Smith-Magenis syndrome (SMS) due to a rare small-scale deletion.

Methods: Muscle samples from the the third fetus was collected after the in Medical history and clinical data of the patient were collected. The child and his parents were subjected to chromosome karyotyping analysis, multiplex ligation-dependent probe amplification (MLPA) and copy number variation sequencing (CNV-seq).

Results: The child was found to have a normal karyotype. MLPA and CNV-seq detection showed that he has harbored a 1.22 Mb deletion and a 0.3 Mb duplication in the 17p11.2 region. Neither of his parents was found to have similar deletion or duplication.

Conclusion: The child was diagnosed with SMS due to a rare 1.22 Mb deletion in the 17p11.2 region, which is among the smallest deletions associated with this syndrome.