Chinese doctors reported on Tuesday the discovery of an abnormal karyotype in human chromosome 5, the world's first such case, in northwest China's Shaanxi Province.

Baoji City's maternal and child care service center diagnosed a girl with dwarfism, because of her lacking a sex chromosome and the long arm in chromosome 5 has a kink.

Tang Kai, director of the center's genetics and heredity lab, said the abnormality was first of its kind seen.

Clinical manifestations of the girl's disease are growth retardation and insufficient development of gonads.

The case was reported to the State Key Lab of Medical Genetics, and entered the Database of the China Human Chromosome Abnormality Catalogue.

"Gene analysis on the mutations should be complete to have a clearer view of their clinical effect," Tang added.