Abstract: Objective To improve the understanding of genotype and phenotype of 2q31.1 microdeletion syndrome. Method　The clinical data of 2q31.1 microdeletion syndrome in a child were analyzed, and the relevant literature was reviewed. Results　An 11-month-old girl had global developmental delay and convulsions for 2 times since birth. She presented with special faces, deformity of extremities, decreased muscle tension of limbs, deformity of toes and fingers. MRI of the brain showed dysplasia of the corpus callosum. The microdeletions of 7.279 Mb in 2q31.1-2q31.3 region: arr 2q31.1q31.3 (174570453-181849708) ×1 were confirmed by chromosome chip detection and comparative genomic hybridization (array CGH). The child was diagnosed with 2q31.1 microdeletion syndrome finally. It has been reported that the haploinsufficiency of HOXO gene cluster and its regulatory sequence in 2q31.1 microdeletion syndrome leads to limb deformity. The loss-of-function mutations of LNPK result in neurodevelopmental disorders with convulsive seizures and corpus callosum hypoplasia, characterized by psychomotor retardation, mental retardation, hypotonia, convulsive seizures and corpus callosum hypoplasia. The neurological involvement of this child is similar to the phenotype of LNPK single gene mutation. Thus, it is speculated that the neurological involvement of the child may be caused by haploinsufficiency of LNPK. Conclusion　It is necessary to be aware of 2q31.1 microdeletion syndrome in patients with global developmental delay and limb deformity.

Key words: 　chromosome 2;　2q31.1 microdeletion syndrome;　limb deformity