This study reported a case of micropenis caused by a novel hemizygous mutation in the ADGRG2 gene, which aimed to expand the understanding of sexual dysplasia caused by ADGRG2 gene mutation.We present the clinical data and genetic test results of a patient with micropenis admitted in September, 2022, to the Tongji Hospital. The patient was a 9-year-10- month-old male whose chief complaint was the presence of a short penis over a period of three years. In April 2016, the patient underwent corrective surgery for a clubbed penis. Upon admission to the study hospital, his height and weight were 145.0 cm (75-90th percentile) and 37.8 kg (50-75th percentile), respectively, and his BA was 12 years old. His physical characteristics included a normal face, bilateral testicle size of 2 ml, and penile length of about 3 cm. A gonadotrophin-releasing hormone-stimulating test revealed normal hypothalamic-pituitary-gonadal axis function. An HCG stimulation test indicated normal sperm production in the testis. Key abnormalities from auxiliary examinations included low testosterone and high ACTH, dehydroepiandrosterone sulfate, androstenedione, and 17-OH-P levels. Genetic testing revealed a new hemizygous mutation, a splicing mutation in intron 4 of the ADGRG2 gene (ChrX: 19040187 (NM_001079858.3): c.154 + 2T > A, inherited from the mother.This study reported a case of micropenis caused by a new hemizygous mutation in the ADGRG2 gene. This indicates the importance of genetic testing and gene-guided treatments to improve prognosis.Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.