Genotype-Phenotype Correlation Reanalysis in 83 Chinese Cases with OCRL Mutations

Background: Both Lowe syndrome and Dent-2 disease are caused by variants in the OCRL gene. However, the reason why patients with similar OCRL gene mutations presented with different phenotypes remains uncertain.

Methods: Children with hemizygous pathogenic or likely pathogenic variants in OCRL were compiled from published and unpublished consecutive cases from China. Furthermore, a Chi-square test was employed to analyze the correlation of the location and types of mutations on the phenotype of children with Lowe syndrome or Dent-2 disease.

Results: Among the total 83 patients, 70.8% (34/48) cases of Lowe syndrome presented with truncating mutations, while only 31.4% (11/35) cases of Dent-2 disease presented with truncating mutation (Χ² = 12.662; P < 0.001). Meanwhile, the majority of mutations in Dent-2 disease are located in Exon 2-12 (21/35, 60.0%), while the majority of mutations in Lowe syndrome are located in Exon 13-23 (39/48, 81.3%; Χ² = 14.922; P < 0.001).

Conclusions: Truncating mutations of the OCRL gene were more common in patients with Lowe syndrome than in Dent-2 disease, while mutation is more likely located at exon 2-12 in Dent-2 disease than that in Lowe syndrome. The type and location of mutation are important indicators for the phenotypes in patients with OCRL mutation. This is a large cohort study analyzing the genotype-phenotype correlation in patients with Lowe syndrome and Dent-2 disease in China. Our data may improve the interpretation of new OCRL variants and genetic counseling. Furthermore, a large international study would be necessary to illustrate the genotype-phenotype correlation in patients with OCRL mutations.