Background: Alport syndrome (AS) is a common and heterogeneous genetic kidney disease, that often leads to end-stage kidney disease (ESKD). Methods: This is a single-center, retrospective study that included 36 adults with type IV collagen (COL4) mutations. Our main scope was to describe how genetic features influence renal survival. Results: A total of 24 different mutations were identified, of which eight had not been previously described. Mutations affecting each of the type IV collagen α chains were equally prevalent (33.3%). Most of the patients had pathogenic variants (61.1%). Most patients had a family history of kidney disease (71%). The most prevalent clinical picture was nephritic syndrome (64%). One-third of the subjects had extrarenal manifestations, 41.6% of patients had ESKD at referral, and another 8.3% developed ESKD during follow-up. The median renal survival was 42 years (95% CI, 29.98–54.01). The COL4A4 group displayed better renal survival than the COL4A3 group (p = 0.027). Patients with missense variants had higher renal survival (p = 0.023). Hearing loss was associated with lower renal survival (p < 0.001). Conclusions: Patients with COL4A4 variants and those with missense mutations had significantly better renal survival, whereas those with COL4A3 variants and those with hearing loss had worse prognoses.

Background/Objectives: We sought to evaluate the clinical predictors of underlying histologic activity in patients with lupus nephritis (LN), with a focus on urinary soluble protein CD163 (usCD163). Methods: We conducted a retrospective, cross-sectional study of forty-two consecutive LN patients with concurrent determination of usCD163 at the moment of kidney biopsy. A first morning void prior to the kidney biopsy was collected and usCD163 was measured by a commercial ELISA assay (EUROIMMUN, Lubeck, DE). Results: The study cohort had a median age at the moment of kidney biopsy of 33.5 (IQR: 24–42.7) years. The mean eGFR and median 24 h proteinuria were 76.6 ± 33.9 mL/min/1.73 m² and 1.98 (IQR: 0.83–4.52) g/day. The median activity (AI) and chronicity (CI) indices were 7 (IQR: 3–11) and 3 (IQR: 1–5), respectively. usCD163 significantly correlated with 24 h proteinuria (r = 0.7, p < 0.001), hematuria (r = 0.51, p < 0.001), and serum complement levels, C3 (r = −0.5, p = 0.001) and C4 (r = −0.32, p = 0.03), but not with eGFR (r = −0.23, p = 0.14). Regarding the histological parameters, usCD163 significantly correlated with the AI and the individual active lesions (except for fibrinoid necrosis), but not with CI or any chronic lesion. usCD163 had a higher AUC compared to the classical measures of renal involvement (proteinuria, hematuria, eGFR) for discriminating an elevated AI, but the differences between AUC reached statistical significance only for hematuria. Thus, the AUC of usCD163 was 0.74 (95%CI, 0.58–0.86) for an AI over 2, an AUC of 0.77 (95%CI, 0.61–0.88) for an AI over 3 and an AUC of 0.74 (95%CI, 0.57–0.86) for an AI of at least 9. The optimal cutoff value for usCD163 identified for all AI thresholds evaluated was 296.2 ng/mmol. Conclusions: usCD163 correlates with glomerular inflammation, being able to discriminate histologic activity from chronicity in patients with LN and identify minimal histologic activity, although it did not significantly outperform proteinuria.