Autosomal recessive osteopetrosis (ARO) is a rare genetic bone disease characterized by dense and fragile bone, caused by a defect in osteoclasts responsible for the bone destruction. In this study, we aimed to investigate the mutations in TCIRG1 and SNX10 that are responsible for 50% and 4% of the cases, respectively. All amplicons were sequenced by Sanger sequencing following PCR amplification. As a result, six different mutations of the TCIRG1 gene were found in five of the twelve unrelated cases. These include two novel mutations, namely c.630 + 1G > T mutation and c.1778_1779delTG mutation of the gene which are identified as homozygous. A compound heterozygosity of known mutations c.649_674del26 and c.1372G > A and homozygous presence of the known c.2235 + 1G > A mutation were also observed in different patients. In addition, as a result of the prenatal testing in a family with osteopetrosis infant, the c.1674-1G > A mutation was detected as homozygous for the fetus. In TCIRG1, c.166C > T change, which is indicated as likely benign according to ClinVar database, was heterozygous. Several known polymorphisms; c.117 + 83 T > C, c.417 + 11A > G and c.714-19C > A in TCIRG1 gene; c.24 + 36 T > A and c.112-84G > A in SNX10 gene were also detected. In conclusion, our study revealed that five of the twelve cases carry at least one mutation of TCIRG1 gene. Further studies with more patients and other genes would help better understanding of genetic etiology of the disease.