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Kidney Week

Abstract: PO1298

Genotype-Phenotype Analyses in Korean X-Linked Alport Syndrome: A Multicenter Study

Session Information

Category: Genetic Diseases of the Kidneys

  • 1002 Genetic Diseases of the Kidneys: Non-Cystic

Authors

  • Kim, Ji hyun, Seoul National University Bundang Hospital, Seongnam, Korea (the Republic of)
  • Cheong, Hae Il, Hallym University Dongtan Sacred Heart Hospital, Hwaseong, Gyeonggi, Korea (the Republic of)
  • Kang, Hee Gyung, Seoul National University Hospital, Jongno-gu, Seoul, Korea (the Republic of)
  • Ahn, Yo Han, Seoul National University Hospital, Jongno-gu, Seoul, Korea (the Republic of)
Background

X-linked (XL) inheritance, caused by COL4A5 mutation, is most common in Alport syndrome (AS). Many clinical studies have elucidated the correlation between genotype and phenotype in male XLAS, whereas no association has been found in female XLAS. Here, we analyzed genotype-phenotype correlation in Korean XLAS.

Methods

This multicenter, retrospective study collected XLAS cases who had been diagnosed from 1985 to Jan 2021 in 13 tertiary centers of Korea. Sanger or next-generation sequencing were conducted in clinically suspected AS patients (male:female 96:42 from 121 Korean families) for genetic confirmation. We divided the cases into three groups according to the genetic variant types: 1=missense or in-frame mutations (n=46); 2=splicing mutations (n=12); 3=frameshift or nonsense mutations (n=38). Kidney survival was compared between the groups using Kaplan-Meier method.

Results

For male XLAS, median age of presentation was 5.1 years (yrs) and onset symptoms were gross hematuria (n=24), asymptomatic urinary abnormality (n=25) or nephrotic syndrome (n=19). At last follow-up, 54 (56.3%) patients had reached CKD G5 (median age 20.0 yrs)) and renin-angiotensin system inhibitors (RASi) were used in nearly all the patients. Hearing loss (HL) was present in 50%. Kidney survival rate was significantly different (median age of group 1, 29.0 yrs; group 2, 21.4 yrs; group 3, 20.6 yrs, p=0.014). HL showed a similar trend by mutant types (group 1, 32.6%; group 2, 58.3%; group 3, 68.4%; p=0.002). Female XLAS presented at median age of 3.0 yrs and 9 (21.4%) patients were reached CKD G5 at median age of 29.2 yrs. HL was present in 14.3%. Kidney survival was not significantly correlated with variant types.

Conclusion

There were strong genotype-phenotype correlation in male Korean XLAS. Both male and female XLAS showed similar results consistent with previous papers according to mutant types, but kidney survival rate was worse for all variant types, despite the appropriate use of RASi. These data could potentially be helpful of counseling in Korean families with XLAS.