| Literature DB >> 36090564 |
Zhechi He1, Ke Wu2, Wenqing Xie1, Jianghua Chen1.
Abstract
Background: Focal segmental glomerulosclerosis (FSGS) is a histopathological diagnosis of the sclerosis of glomeruli and the damage to renal podocytes. FSGS affects the filtration function of the kidneys and results in nephrotic syndrome (NS) in children and adults. FSGS is a clinically and genetically heterogeneous disorder. FSGS-1 [OMIM #603278] is one of the progressive hereditary renal diseases. It is caused by heterozygous variants of the actinin alpha 4 (ACTN4) [OMIM*604638] gene on chromosome 19q13.2 in a dominant inheritance (AD) manner. With the recent development of whole-exome sequencing (WES), 22 (including our case) pathogenic or likely pathogenic variants have been identified in ACTN4 gene. Case presentation: We reported a 17-year-old Chinese girl who was hospitalized with foamy urine, nausea and vomiting. Laboratory tests revealed increased levels of serum creatinine and urea nitrogen. Ultrasonography demonstrated bilaterally reduced size of kidneys. The primary diagnoses were NS and chronic kidney disease stage 5 (CKD5). The hemodialysis was initiated in 48 h after admission. After 4 months of treatment, the patient received an allogeneic kidney transplantation from her father. A novel heterozygous missense variant c.494C > T (p.A165V) in the ACTN4 gene was found by WES in the patient. This variant was confirmed by Sanger sequencing. The computational simulation of the stability of mutant protein (p.A165V) was decreased. Interatomic interactions of the p.A165V site were increased, and it might be associated with the increased ubiquitylation in the vicinity of the mutant site.Entities:
Keywords: ACTN4; de novo; end-stage renal disease; focal segmental glomerulosclerosis; proteinuria
Year: 2022 PMID: 36090564 PMCID: PMC9452832 DOI: 10.3389/fped.2022.930258
Source DB: PubMed Journal: Front Pediatr ISSN: 2296-2360 Impact factor: 3.569
FIGURE 1The Chinese patient’s pedigree.
FIGURE 2The results of Sanger sequencing (ACTN4 variant was marked with red arrows).
FIGURE 3In total, 30 amino acids surrounding the variant position (marked with a black box).
FIGURE 4The schematic diagram of ACTN4 variants and ACTN4 protein’s domains (UniProtKB-O43707). The patient’s ACTN4 variant was marked with a red box.
FIGURE 5Prediction of interatomic interactions of p.A165V (A,B) and p.G195D (C,D). Residues 165 and 195 in the wild-type and mutant proteins (p.A165V and p.G195D) are colored in light green and are shown as sticks. The respective chemical interactions are labeled as dotted lines and colored as follows: hydrogen bonds—(red), weak hydrogen bonds—(orange), hydrophobic contacts—(green), amide-amide contacts—(blue), and ionic interactions—(gold). Amino acid residues are also colored according to type, namely; nitrogen (blue), oxygen (red), and sulfur (yellow). In comparison with wild-type sites, some interactions were observed to be added in mutant sites.
Genotypes and phenotypes of patients with ACTN4 variants previously reported.
| References | Ethnicity | Gender | Family history | Age of onset | Initial symptoms or diagnosis | Histopathology diagnosis | Time to ESKD | Age of kidney transplant | Origin of variant | Protein domain | Evidence of pathogenicity | Pathogenicity | |
| Weins et al. ( | Western European | M | FH | 5 | Proteinuria | FSGS | 3 y | 10 | c.175T > C (p.W59R) |
| ABD | PS2, PS3, PM1, PM2, PP3, PP4 | Pathogenic |
| Dai et al. ( | Chinese | ND | S | ND | ND | FSGS | ND | ND | c.184T > A (p.S62T) |
| ABD | PS2, PM1, PM2, PP3, PP4 | Pathogenic |
| Weins et al. ( | ND | ND | ND | ND | Proteinuria | FSGS | ND | ND | c.214G > C (p.E72Q) | ND | ABD | PM1, PM2, PP3, PP4 | Likely pathogenic |
| Rodrigues et al. ( | Colombian | ND | ND | ND | ND | FSGS | ND | ND | c.448_450delATC (p.I150del) | ND | ABD | PM1, PM2, PM4, PP3, PP4 | Likely pathogenic |
| Barua et al. ( | ND | ND | ND | ND | Proteinuria | FSGS | ND | ND | c.457T > C (p.F153L) | ND | ABD | PM1, PM2, PP3, PP4 | Likely pathogenic |
| Giglio et al. ( | Caucasian | F | S | 3 | SRNS | FSGS | ND | ND | c.464T > C (p.I155T) |
| ABD | PS2, PM1, PM2, PP3, PP4 | Pathogenic |
| Bezdíčka et al. ( | Czech | F | ND | 15.1 | SRNS | ND | ND | ND | c.475 T > C (p.S159P) | ND | ABD | PM1,PM2, PP3, PP4 | Likely pathogenic |
| Bartram et al. ( | German | F | S | 13 | ESKD | ND | ND | 14 | c.584G > A (p.G195D) |
| ABD | PS2, PS3, PM1, PM2, PP3, PP4 | Pathogenic |
| Nagano et al. ( | Japanese | M | ND | 6 | Proteinuria | FSGS | 7 y | ND | c.671T > C (p.L224P) |
| ABD | PS2, PM1, PM2, PP3, PP4 | Pathogenic |
| Kaplan et al. ( | Oklahoma | ND | ND | ND | ND | FSGS | ND | ND | c.763A > G (p.K255E) | ND | ABD | PS3, PM1, PM2, PP3, PP4 | Pathogenic |
| Bartram et al. ( | Canary Islands | ND | ND | ND | ND | FSGS | ND | ND | c.776C > T (p.T259I) | ND | ABD | PS3, PM1, PM2, PP3, PP4 | Pathogenic |
| Sen et al. ( | ND | M | ND | 6 | SRNS | FSGS | ND | ND | c.776C > A (p.T259N) | ND | ABD | PM1, PM2, PM5, PP3, PP4 | Likely pathogenic |
| Dai et al. ( | Caucasian | F | S | 7 | SRNS | FSGS | 8 y, 9 m | 11 | c.782T > A (p.V261E) |
| ABD | PS2, PM1, PM2, PP3, PP4 | Pathogenic |
| Kakajiwala et al. ( | Caucasian | F | S | 5 | NS | FSGS | 6 m | 6 | c.784T > C (p.S262P) |
| ABD | PS2, PM1, PM2, PP3, PP4 | Pathogenic |
| Choi et al. ( | Korean | M | S | 3 | Proteinuria | FSGS | ND | ND | c.785C > T (p.S262F) | Germline mosaicism from the father’s sperm | ABD | PM1, PM2, PM5, PP3, PP4 | Likely pathogenic |
| F | 3.7 | Proteinuria | FSGS | ND | 5.7 | ||||||||
| Bierzynska et al. ( | White | M | S | 12 | SRNS | FSGS | 1 y, 4 m | ND | c.778_786del | ND | ABD | PM1, PM2, PM4, PP3, PP4 | Likely pathogenic |
| Feng et al. ( | European American | F | S | 14 | NS | FSGS | 6 m | 16 | c.793T > C (p.Y265H) | ND | ABD | PS3, PM1, PM2, PP3, PP4 | Pathogenic |
| Nagano et al. ( | Japanese | M | ND | 8 | Proteinuria | FSGS | ND | ND | c.912 + 1G > A | ND | - | PM2, PM6, PP3, PP4 | Likely pathogenic |
| Rodrigues et al. ( | Black | F | S | 20 | Proteinuria | FSGS | ND | ND | c.1043A > G (p.Q348R) | ND | Spectrin | PS3, PM2, PM6, PP3, PP4 | Pathogenic |
| Schapiro et al. ( | Kurd | M | ND | ND | Proteinuria, | FSGS | ND | ND | c.1606C > A (p.R536S) | ND | Spectrin | PM2, PM6 PP3, PP4 | Likely pathogenic |
| Safaříková et al. ( | Czech | F | FH | 54 | NS | FSGS | ND | ND | c.2242A > G (p.N748D) | ND | Spectrin | PM2, PM6 PP3, PP4 | Likely pathogenic |
| Our patient | Chinese | F | S | 17 | Proteinuria | ND | ND | 17 | c.494C > T (p.A165V) |
| ABD | PS2, PM1, PM2, PP3, PP4 | Pathogenic |
M, male; F, female; y, years; m, month; FH, family history; S, sporadic; ESKD, end-stage kidney disease; ND, not done or no data; ABD, actin binding domain; FSGS, focal segmental glomerulosclerosis; NS, nephrotic syndrome; SRNS, steroid-resistant nephrotic syndrome; PS2, de novo (both maternity and paternity confirmed) in a patient with the disease and no family history; PS3, well-established in vitro or in vivo functional studies supportive of a damaging effect on the gene or gene product; PM1, variants located in a mutational hot spot and/or critical and well-established functional domain (e.g., active site of an enzyme) without benign variation; PM2, variants were absent from controls; PM4, protein length changes as a result of in-frame deletions/insertions in a non-repeat region or stop-loss variants; PM5, novel missense change at an amino acid residue where a different missense change determined to be pathogenic has been seen before; PM6, assumed de novo, but without confirmation of paternity and maternity; PP3, multiple lines of computational evidence support a deleterious effect on the gene or gene product; PP4, patients’ phenotype or family history is highly specific for a disease with a single genetic etiology.
The known variants of VUS in the ACTN4 gene.
| Patients’ diagnosis | Evidence of pathogenicity | Pathogenicity | References | |
| c.459C > G (p.F153L) | Unknown | PM1, PM2, PP3 | VUS | PMID: 33226606 |
| c.485-7T > C | Developmental disorder | PM2, BP4 | VUS | PMID: 28135719 |
| c.734-26C > G | SRNS | PM2, BP4 | VUS | PMID: 29869118 |
| c.845G > A (p.C282Y) | Bronchopulmonary dysplasia | PM2, PP3 | VUS | PMID: 31848748 |
| c.929G > A (p.R310Q) | FSGS | PS3, BP4, BP6 | VUS | PMID: 21680739 |
| c.1279G > A (p.A427T) | SRNS | PM2, BP4 | VUS | PMID: 29869118 |
| c.1660A > G (p.M554V) | Autism spectrum disorder | PS2, PM2, BP4 | VUS | PMID: 25363768 |
| c.2020C > T (p.R674C) | SRNS | PM2, PP3 | VUS | PMID: 25903641 |
| c.2084G > A (p.R695H) | SRNS | PM2, BP4 | VUS | PMID: 28780565 |
| c.2351C > T (p.A784V) | IgA nephropathy | PM2, BP4 | VUS | PMID: 23890478 |
| c.2378G > A (p.C793Y) | IgA nephropathy | PM2, PP3 | VUS | |
| c.2401G > A (p.p.V801M) | FSGS | PM2, BP4, BP6 | VUS | PMID: 24130771 |
| c.2620G > A (p.D874N) | SRNS | PM2, BP4, | VUS | PMID: 30406062 |
| c.2629G > A (p.E877K) | SRNS | PM2, PP3 | VUS | PMID: 28780565 |
FSGS, focal segmental glomerulosclerosis; SRNS, steroid-resistant nephrotic syndrome; PVS1, null variant (nonsense, frameshift, canonical ± 1 or 2 splice sites, initiation codon, single or multiexon deletion) in a gene where LOF is a known mechanism of disease; PS2, de novo (both maternity and paternity confirmed) in a patient with the disease and no family history; PS3, well-established in vitro or in vivo functional studies supportive of a damaging effect on the gene or gene product; PM1, variants located in a mutational hot spot and/or critical and well-established functional domain (e.g., active site of an enzyme) without benign variation; PM2, variants were absent from controls; PM4, protein length changes as a result of in-frame deletions/insertions in a non-repeat region or stop-loss variants; PP3, multiple lines of computational evidence support a deleterious effect on the gene or gene product; PP5, reputable source recently reports variant as pathogenic, but the evidence is not available to the laboratory to perform an independent evaluation; BP4, multiple lines of computational evidence suggest no impact on gene or gene product (conservation, evolutionary, splicing impact, etc.); BP6, reputable source recently reports variant as benign, but the evidence is not available to the laboratory to perform an independent evaluation; CKD, chronic kidney disease; VUS, variants of unknown significance.