A novel proximal 3q29 chromosome microdeletion in a Chinese patient with Chiari malformation type II and Sprengel's deformity.

Background: Chiari malformation type II (CM-II) is mainly characterized by elongation and descent of the cerebellum through the foramen magnum into the spinal canal. Moreover, CM-II is uniquely associated with myelomeningocele. Sprengel's deformity refers to the malposition of the scapula, i.e. scapular elevation which is sometimes accompanied with scapula dysplasia. Although few familial cases of CM-II and Sprengel's deformity have been previously reported, both of these defects are considered to be sporadic, thus the exact etiology and causative genes have largely remained unknown.

Case presentation: The patient was diagnosed with CM-II accompanied with Sprengel's deformity. Further genetic investigation revealed a novel 666 kb microdeletion located in 3q29 (chr3:194,532,035-195,198,585; Hg19). Subsequently, genes within the affected region were summarized, and XXYLT1 and ACAP2 were identified as the candidate genes.

Conclusion: We reported a case of a patient with CM-II and Sprengel's deformity harboring a microdeletion in 3q29. This case highlights the importance of 3q29 in early neural and skeletal development, as well as expands the phenotype spectrum of this rare disorder.