Background Congenital anomalies of kidneys and urinary tract (CAKUT) are the most predominant developmental disorders comprising ∼20–30% of all anomalies identified in the prenatal period. Mutations in hepatocyte nuclear factor 1-beta (HNF-1β) involved in the development of kidneys, liver, pancreas and urogenital tract are currently the most frequent monogenetic cause of CAKUT found in 10–30% of patients depending on screening policy and study design. We aimed to validate criteria for analysis of HNF1B in a prospective cohort of paediatric and adult CAKUT patients. Methods We included CAKUT patients diagnosed in our paediatric and adult nephrology departments from January 2010 until April 2013 based on predefined screening criteria. Subjects presenting with at least one major renal criterion or one minor renal criterion combined with one or more extra-renal criteria in the personal history or a familial history of renal or extra-renal manifestations were considered eligible. Results We prospectively screened 205 patients and detected HNF1B mutations in 10% [n = 20, 12 children, median age 4.2 (range 0–13.1) years and 8 adults, median age 34.8 (range 16.6–62) years]. We observed that bilateral renal anomaly, renal cysts from unknown origin, a combination of two major renal anomalies and hypomagnesaemia were predictive for finding HNF1B mutations (P < 0.001; P < 0.001; P = 0.004; P = 0.008, respectively). Conclusions We demonstrated that HNF1B mutations are responsible for ∼10% of CAKUT cases, both in children and in adults. Based on our results we propose adapted criteria for HNF1B analysis to reduce the screening costs without missing affected patients. These criteria should be reaffirmed in a larger validation cohort.

To investigate growth patterns and anthropometrics in former extremely low birth weight (ELBW, 0.67 SDS. At 11 years, anthropometrics, neurocognitive performance, body composition, grip strength and puberty scores were assessed. ELBW neonates displayed extra–uterine growth restriction with mean Z–scores for height, weight and head circumference of –0.77, –0.93 and –0.46 at birth, –1.61, –1.67 and –0.72 at 9 months, –1.22, –1.61 and –0.84 at 24 months, and –0.42, –0.49 and –1.09 at 11 years. ELBW children performed consistently worse on neurocognitive testing with an average intelligence quotient equivalent at 11 years of 92.5 (SD 13.1). Catch–up growth was not associated with neurocognitive performance. Compared to controls, ELBW cases had lower grip strength (13.6 vs. 15.9 kg) and percentage lean body weight (75.1 vs. 80.5%), but higher body fat (24.6 vs. 19.2%) and advanced puberty scores at 11 years (all P≤0.025). Catch–up growth for weight and height in the first two years of life in cases was associated with a lower percentage body fat compared to cases without catch–up growth (16.8% catch-up growth for weight vs. 25.7%, P<0.001; 20.9% catch-up for height vs. 25.8%, P = 0.049). In young adolescence, former ELBW children still have difficulties to reach their target height. Compared to normal birth weight controls, ELBW adolescents show lower neurocognitive performance and grip strength and a higher percentage body fat, a potential risk factor for adverse health outcomes in adulthood. Our key finding is that catch–up growth in ELBW children in the first two years of life is associated with a lower percentage body fat and is therefore likely to be beneficial.

Low birth weight and prematurity are risk factors for hypertension in adulthood. Few studies in preterm or full-term born children reported on plasma renin activity (PRA). We tested the hypothesis that renin might modulate the incidence of hypertension associated with prematurity. We enrolled 93 prematurely born children with birth weight <1000 g and 87 healthy controls born at term, who were all examined at ≈11 years. Renal length and glomerular filtration rate derived from serum cystatin C were 0.28 cm (95% confidence interval, 0.09–0.47) and 11.5 mL/min per 1.73 m ² (6.4–16.6) lower in cases, whereas their systolic/diastolic blood pressure (BP) was 7.5 mm Hg (4.8–10.3)/4.0 mm Hg (2.1–5.8) higher ( P <0.001 for all). The odds of having systolic prehypertension or systolic hypertension associated with extreme low birth weight were 6.43 (2.52–16.4; P <0.001) and 10.9 (2.46–48.4; P =0.002). Twenty-four hours of urinary sodium excretion was similar in cases and controls (102.1 versus 106.8 mmol; P =0.47). Sodium load per nephron was estimated as sodium excretion divided by kidney length (mmol/cm). PRA was 0.54 ng/mL per hour (0.23–0.85; P =0.001) lower in cases. PRA, systolic BP, and sodium load were available in 43 cases and 56 controls. PRA decreased with systolic BP (slope −0.022 ng/mL per hour/ ^{− mm Hg} ; P =0.048), but was unrelated to sodium load (slope +0.13 mmol/cm ^{− mm Hg} ; P =0.54). The slope of PRA on systolic BP was similar ( P =0.17) in cases and controls. In conclusion, extremely low birth weight predisposes young adolescents to low-renin hypertension, but does not affect the inverse association between PRA and BP. Clinical Trial Registration—: URL: https://www.clinicaltrials.gov . Unique identifier: NCT02147457.