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Lee B, Lee SY, Han DH, Park HD. Interpretation of SLC3A1 and SLC7A9 variants in cystinuria patients: The significance of the PM3 criterion and protein stability. Urolithiasis 2023; 51:94. [PMID: 37439839 PMCID: PMC10345071 DOI: 10.1007/s00240-023-01466-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 06/27/2023] [Indexed: 07/14/2023]
Abstract
Cystinuria is a genetic disorder caused by defects in the b0,+ transporter system, which is composed of rBAT and b0,+AT coded by SLC3A1 and SLC7A9, respectively. Variants in SLC3A1 and SLC7A9 follow autosomal recessive inheritance and autosomal dominant inheritance with reduced penetrance, respectively, which complicates the interpretation of cystinuria-related variants. Here, we report seven different SLC3A1 variants and six different SLC7A9 variants. Among these variants were two novel variants previously not reported: SLC3A1 c.223C > T and SLC7A9 c.404A > G. In silico analysis using REVEL correlated well with the functional loss upon SLC7A9 variants with scores of 0.8560-0.9200 and 0.4970-0.5239 for severe and mild decrease in transport activity, respectively. In addition, DynaMut2 was able to predict a decreased protein expression level resulting from the SLC7A9 variant c.313G > A with a ΔΔGStability -2.93 kcal/mol. Our study adds to the literature as additional cases of a variant allow applying the PM3 criterion with higher strength level. In addition, we suggest the clinical utility of REVEL and DynaMut2 in interpreting SLC3A1 and SLC7A9 variants. While a decreased protein expression level is not embraced in the current variant interpretation guidelines, we believe in silico protein stability predicting tools could serve as evidence of protein function loss.
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Affiliation(s)
- Beomki Lee
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul, 06351, Korea
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea
| | - Soo-Youn Lee
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul, 06351, Korea
| | - Deok Hyun Han
- Department of Urology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul, 06351, Korea.
| | - Hyung-Doo Park
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul, 06351, Korea.
- Department of Medical Device Management and Research, SAIHST, Sungkyunkwan University, Seoul, 06355, Korea.
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Vinit N, Khoury A, Lopez P, Heidet L, Botto N, Traxer O, Boyer O, Blanc T, Lottmann HB. Extracorporeal Shockwave Lithotripsy for Cystine Stones in Children: An Observational, Retrospective, Single-Center Analysis. Front Pediatr 2021; 9:763317. [PMID: 34869121 PMCID: PMC8636798 DOI: 10.3389/fped.2021.763317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 10/15/2021] [Indexed: 11/18/2022] Open
Abstract
Purpose: Cystinuria is a genetic disorder characterized by a defective reabsorption of cystine and dibasic amino acids leading to development of urinary tract calculi from childhood onward. Cystine lithiasis is known to be resistant to fragmentation. The aim was to evaluate our long-term experience with extracorporeal shockwave lithotripsy (ESWL) used as first-line urological treatment to treat cystine stones in children. Methods: We retrospectively reviewed the charts of all children who underwent ESWL for cystine stone. We assessed the 3-month stone-free rate, according to age, younger (group 1) or older (group 2) than 2 years old. Results: Between 2003 and 2016, 15 patients with a median (IQR) age at first treatment of 48 (15-108) months underwent ESWL in monotherapy. Median age was, respectively, 15 and 108 months in each group. The median (IQR) stone burden was 2,620 (1,202-8,265) mm3 in group I and 4,588 (2,039-5,427) mm3 in group II (p = 0.96). Eleven patients had bilateral calculi. ESWL was repeated on average 2.4 times, with a maximum of 4 for patients of group I, and 4.8 times, with a maximum of 9 for group II (p > 0.05). ESWL in monotherapy was significantly more efficient to reach stone-free status for children under 2 years of age: 83% vs. 6.2% (p = 0.040). The median (IQR) follow-up of the study was 69 (42-111) months. Conclusion: ESWL appears as a valid urological option for the treatment of cystine stones, in young children. Even if cystine stones are known to be resistant to fragmentation, we report 83% of stone-free status at 3 months with ESWL used in monotherapy in children under 2 years old with cystinuria. In older children, the success rate is too low to recommend ESWL as a first line approach.
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Affiliation(s)
- Nicolas Vinit
- Department of Pediatric Surgery and Urology, Necker-Enfants Malades Hospital, APHP, Paris, France
| | - Antoine Khoury
- Department of Pediatric Surgery and Urology, Necker-Enfants Malades Hospital, APHP, Paris, France
| | - Pauline Lopez
- Department of Pediatric Surgery and Urology, Necker-Enfants Malades Hospital, APHP, Paris, France
| | - Laurence Heidet
- Department of Pediatric Nephrology, Reference Center for Inherited Renal Disease (MARHEA), Necker-Enfants Malades Hospital, APHP, Paris, France.,INSERM UMR 1163, Laboratory of Inherited Kidney Diseases, Imagine Institute, Université de Paris, Paris, France
| | - Nathalie Botto
- Department of Pediatric Surgery and Urology, Necker-Enfants Malades Hospital, APHP, Paris, France
| | - Olivier Traxer
- Department of Urology, Tenon Hospital, APHP, Paris, France.,Groupe de Recherche Clinique sur la Lithiase Urinaire (GRC no 20), Tenon Hospital, Sorbonne Université, Paris, France.,Sorbonne Université, Paris, France
| | - Olivia Boyer
- Department of Pediatric Nephrology, Reference Center for Inherited Renal Disease (MARHEA), Necker-Enfants Malades Hospital, APHP, Paris, France.,INSERM UMR 1163, Laboratory of Inherited Kidney Diseases, Imagine Institute, Université de Paris, Paris, France.,Université de Paris, Paris, France
| | - Thomas Blanc
- Department of Pediatric Surgery and Urology, Necker-Enfants Malades Hospital, APHP, Paris, France.,Université de Paris, Paris, France.,INSERM U1151-CNRS UMR 8253, Université de Paris, Paris, France
| | - Henri B Lottmann
- Department of Pediatric Surgery and Urology, Necker-Enfants Malades Hospital, APHP, Paris, France
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