[Item Reduction to Improve Practicability of Neonatal Pain Assessment Tools - Comparison of NFCSshort and PIPP in Daily Clinical Practice]. / Itemreduktion zur Verbesserung der Praktikabilität neonatologischer Schmerzmesssysteme.

HINTERGRUND: Trotz über 50 psychometrisch validierter Beobachtungsverfahren gibt es bisher keinen Konsens über das praktikabelste Schmerzassessment bei Neugeborenen. Die Items von NFCSshort und PIPP wurden mit der Schmerzeinschätzung der prozedurbeteiligten Behandler verglichen und es wurde evaluiert, ob eine Itemreduktion zu Gunsten der Alltagsanwendung möglich wäre. MATERIAL UND METHODEN: 52 Neugeborene wurden in unserer Beobachtungsstudie einer klinisch indizierten peripheren Venenpunktion unterzogen. Patient und Monitordaten wurden standardisiert auf Video aufgezeichnet. Die Schmerzintensität wurden durch sieben unabhängige Untersucher mittels NFCSshort und PIPP bewertet und hinsichtlich der Variabilität zwischen den Untersuchern verglichen. ERGEBNISSE: Nur vier Items des PIPP (Herzfrequenz, Augenbrauenvorwölbung, zusammengekniffene Augen, betonte Nasolabialfalte) wiesen einen signifikanten Zusammenhang mit der geschätzten Schmerzhaftigkeit der Prozedur auf. Die Items 1 (Gestationsalter), 2 (Wachheitsgrad) und 4 (Sauerstoffsättigung) hatten bei keinem Untersucher Einfluss auf das Schmerzmessergebnis. Die Auswertung des NFCSshort zeigte bei zwei Untersuchern für das Item 1 (Vorwölbung der Augenbrauen) und bei einem Untersucher für das Item 2 (zusammengekniffene Augen) keine Einflüsse auf das Messergebnis. DISKUSSION: Die Ergebnisse der Studie legen eine Kürzung des PIPP um drei Items nahe, da diese keinen Einfluss auf das Schmerzmessergebnis zeigten. Eine Reduktion des PIPP um das Item Gestationsalter erscheint fraglich, da es in weiteren Studien als bedeutsames Item bewertet wurde. Ein Verzicht auf das Item Sauerstoffsättigung geht mit einem geringeren Messaufwand einher. Eine weitere Kürzung der bereits gekürzten Version (NFCSshort) auf weniger als fünf Items ist auf Basis unserer Ergebnisse nicht zu empfehlen. BACKGROUND: Despite more than 50 laboratory-evaluated measurement systems, there is no consensus on the most practicable pain assessment in newborns in daily practice. For this purpose, the items of NFCSshort and PIPP were compared to the pain assesment of the involved medical practitioner. The aim of the study was to evaluate whether an item reduction of the assesments in favor of everyday use is feasible. METHODS: In 52 neonates of a paediatric ward venous blood collection was performed in this observational study. Cameras recorded patients and monitor in a standardized way. The pain intensity was assessed with NFCSshort and PIPP by seven independent observers. The ratings were compared for variability between observers. RESULTS: Of the seven PIPP items, only four were significantly associated with procedural pain assessment for all seven observers (heart rate, brow bulge, eye squeeze, nasolabial furrow). For the NFCSshort, no significant association with procedural pain assessment was found for two observers for the item "brow bulge" and for one observer for the item "eye squeeze". CONCLUSION: The results of the study suggest a possible reduction of the PIPP by three items. Disregarding item 1 (gestational age) appears questionable, since its impact as context variable has been proven repeatedly. The waiver of item 4 (oxygen saturation) is associated with less measuring effort. A further reduction of the already shortened version of the NFCS with ten items (NFCSshort, five items) is not recommended by our results.

[Applicability of Neonatal Pain Scores depending on Level of Education and Work Experience in Child Care]. / Anwendbarkeit neonataler Schmerzscores in Abhängigkeit von Ausbildungsstand und Berufserfahrung in der Kinderpflege.

INTRODUCTION: In management of pain the nursing staff plays a major role in measuring, preventing and treating pain. The influence of general work experience and experience with newborns was investigated by comparing PIPP and NRS measurements in groups with work experience and student nurses. METHODS: 44 students of the nursing school and 35 members of the staff of 2 university hospitals scored the Premature Infant Pain Profile PIPP - a 7 dimensional measurement tool - for 10 videos of painful procedures on preterm and newborn. The subjective impression of the patients' pain was obtained by a NRS. RESULTS: In contrast to the application of one dimensional measurement tools there were no differences between the groups with different experience levels. Also the work experience with newborn did not seem to influence the total PIPP score. Certainly both groups showed a moderate dispersion of the total values (e. g. Video 1: 10,5 [9-12] vs. 10 [3-11]). In NRS students rated the pain lower than experienced nurses. These results were not significant. CONCLUSION: The application of PIPP by students was equal to the application by experienced nurses. The work experience with newborn did not seem to influence the rating. Certainly both groups showed a moderate dispersion of total values (e. g. Video 1: 10,5 [9-12] vs. 10 [3-11]).

Genome-wide association study and meta-analysis identify ISL1 as genome-wide significant susceptibility gene for bladder exstrophy.

The bladder exstrophy-epispadias complex (BEEC) represents the severe end of the uro-rectal malformation spectrum, and is thought to result from aberrant embryonic morphogenesis of the cloacal membrane and the urorectal septum. The most common form of BEEC is isolated classic bladder exstrophy (CBE). To identify susceptibility loci for CBE, we performed a genome-wide association study (GWAS) of 110 CBE patients and 1,177 controls of European origin. Here, an association was found with a region of approximately 220kb on chromosome 5q11.1. This region harbors the ISL1 (ISL LIM homeobox 1) gene. Multiple markers in this region showed evidence for association with CBE, including 84 markers with genome-wide significance. We then performed a meta-analysis using data from a previous GWAS by our group of 98 CBE patients and 526 controls of European origin. This meta-analysis also implicated the 5q11.1 locus in CBE risk. A total of 138 markers at this locus reached genome-wide significance in the meta-analysis, and the most significant marker (rs9291768) achieved a P value of 2.13 × 10-12. No other locus in the meta-analysis achieved genome-wide significance. We then performed murine expression analyses to follow up this finding. Here, Isl1 expression was detected in the genital region within the critical time frame for human CBE development. Genital regions with Isl1 expression included the peri-cloacal mesenchyme and the urorectal septum. The present study identified the first genome-wide significant locus for CBE at chromosomal region 5q11.1, and provides strong evidence for the hypothesis that ISL1 is the responsible candidate gene in this region.

Genome-wide association study and mouse expression data identify a highly conserved 32 kb intergenic region between WNT3 and WNT9b as possible susceptibility locus for isolated classic exstrophy of the bladder.

Bladder exstrophy-epispadias complex (BEEC), the severe end of the urorectal malformation spectrum, has a profound impact on continence as well as sexual and renal functions. It is widely accepted that for the majority of cases the genetic basis appears to be multifactorial. Here, we report the first study which utilizes genome-wide association methods to analyze a cohort comprising patients presenting the most common BEEC form, classic bladder exstrophy (CBE), to identify common variation associated with risk for isolated CBE. We employed discovery and follow-up samples comprising 218 cases/865 controls and 78 trios in total, all of European descent. Our discovery sample identified a marker near SALL1, showing genome-wide significant association with CBE. However, analyses performed on follow-up samples did not add further support to these findings. We were also able to identify an association with CBE across our study samples (discovery: P = 8.88 × 10(-5); follow-up: P = 0.0025; combined: 1.09 × 10(-6)) in a highly conserved 32 kb intergenic region containing regulatory elements between WNT3 and WNT9B. Subsequent analyses in mice revealed expression for both genes in the genital region during stages relevant to the development of CBE in humans. Unfortunately, we were not able to replicate the suggestive signal for WNT3 and WNT9B in a sample that was enriched for non-CBE BEEC cases (P = 0.51). Our suggestive findings support the hypothesis that larger samples are warranted to identify association of common variation with CBE.

The centrosomal protein nephrocystin-6 is mutated in Joubert syndrome and activates transcription factor ATF4.

The molecular basis of nephronophthisis, the most frequent genetic cause of renal failure in children and young adults, and its association with retinal degeneration and cerebellar vermis aplasia in Joubert syndrome are poorly understood. Using positional cloning, we here identify mutations in the gene CEP290 as causing nephronophthisis. It encodes a protein with several domains also present in CENPF, a protein involved in chromosome segregation. CEP290 (also known as NPHP6) interacts with and modulates the activity of ATF4, a transcription factor implicated in cAMP-dependent renal cyst formation. NPHP6 is found at centrosomes and in the nucleus of renal epithelial cells in a cell cycle-dependent manner and in connecting cilia of photoreceptors. Abrogation of its function in zebrafish recapitulates the renal, retinal and cerebellar phenotypes of Joubert syndrome. Our findings help establish the link between centrosome function, tissue architecture and transcriptional control in the pathogenesis of cystic kidney disease, retinal degeneration, and central nervous system development.

Nephrocystin-5, a ciliary IQ domain protein, is mutated in Senior-Loken syndrome and interacts with RPGR and calmodulin.

Nephronophthisis (NPHP) is the most frequent genetic cause of chronic renal failure in children. Identification of four genes mutated in NPHP subtypes 1-4 (refs. 4-9) has linked the pathogenesis of NPHP to ciliary functions. Ten percent of affected individuals have retinitis pigmentosa, constituting the renal-retinal Senior-Loken syndrome (SLSN). Here we identify, by positional cloning, mutations in an evolutionarily conserved gene, IQCB1 (also called NPHP5), as the most frequent cause of SLSN. IQCB1 encodes an IQ-domain protein, nephrocystin-5. All individuals with IQCB1 mutations have retinitis pigmentosa. Hence, we examined the interaction of nephrocystin-5 with RPGR (retinitis pigmentosa GTPase regulator), which is expressed in photoreceptor cilia and associated with 10-20% of retinitis pigmentosa. We show that nephrocystin-5, RPGR and calmodulin can be coimmunoprecipitated from retinal extracts, and that these proteins localize to connecting cilia of photoreceptors and to primary cilia of renal epithelial cells. Our studies emphasize the central role of ciliary dysfunction in the pathogenesis of SLSN.

A hospital-based intermittent nocturnal hemodialysis program for children and adolescents.

OBJECTIVE: To establish a hospital-based nocturnal hemodialysis (NHD) program for children and adolescents. STUDY DESIGN: Sixteen patients (age, 0.5 to 17 years) were prospectively included. Uremia-associated measures as well as amount and dosage of medication were enumerated. Quality of life also was evaluated. Results were compared with data of the same patients on conventional hemodialysis and with matched control subjects (conventional HD). RESULTS: NHD was well tolerated. Median Kt/V values increased. Predialytic mean arterial pressure, urea, phosphate, and parathyroid hormone levels decreased. There was an increase in protein catabolic rate. Dietary and fluid restrictions could be lifted. Amount and dosage of phosphate and potassium binders and antihypertensive medication could be reduced. Quality of life improved and days of absence from school decreased in all patients. CONCLUSIONS: In addition to a better control of uremia-associated measures, NHD allows free dietary and fluid intake and improves patient well-being. Given the continuing shortage of donor organs for kidney transplantation and the high morbidity and mortality on conventional HD, intensified dialysis regimens are a much-needed therapeutic option.

Phenotype severity in the bladder exstrophy-epispadias complex: analysis of genetic and nongenetic contributing factors in 441 families from North America and Europe.

OBJECTIVE: To identify genetic and nongenetic risk factors that contribute to the severity of the bladder exstrophy-epispadias complex (BEEC). STUDY DESIGN: Patients with BEEC from North America (n = 167) and Europe (n = 274) were included. The following data were collected: associated anomalies, parental age at conception, mode of conception, periconceptional folic acid supplementation, maternal risk factors during pregnancy, and environmental risk factors. The patients were divided into 3 subgroups according to phenotype severity: (i) mild, epispadias (n = 43); (ii) intermediate, classic bladder exstrophy (n = 366); and (iii) severe, cloacal exstrophy (n = 31). These subgroups then were compared with identify factors that contribute to phenotype severity. RESULTS: Males were overrepresented in all subgroups. A relatively high prevalence of cleft lip, with or without cleft palate, was observed. Maternal smoking and medical radiation during the first trimester were associated with the severe cloacal exstrophy phenotype. Compliance with periconceptional folic acid supplementation was associated with the mildest phenotype (epispadias). CONCLUSIONS: Periconceptional folic acid supplementation appears to prevent the development of the severe phenotype of BEEC.

Diagnosis and Therapy of Female Genital Malformations (Part 1). Guideline of the DGGG, OEGGG and SGGG (S2k Level, AWMF Registry Number 015/052, May 2019).

Objectives Female genital malformations may take the form of individual entities, they may involve neighboring organs or they may occur in the context of complex syndromes. Given the anatomical structures of the vulva, vagina, uterus and adnexa, the clinical picture of malformations may vary greatly. Depending on the extent of the malformation, organs of the urinary system or associated malformations may also be involved. Methods This S2k-guideline was developed by representative members from different medical specialties and professions as part of the guidelines program of the DGGG, SGGG and OEGGG. The recommendations and statements were developed using a structured consensus process with neutral moderation and voted on. Recommendations The guideline is the first comprehensive presentation of the symptoms, diagnosis and treatment options for female genital malformations. Additional chapters on classifications and transition were included.

Diagnosis and Therapy of Female Genital Malformations (Part 2). Guideline of the DGGG, OEGGG and SGGG (S2k Level, AWMF Registry Number 015/052, May 2019).

Objectives Female genital malformations may be present in the form of individual entities, they may involve neighboring organs or they may occur in the context of complex syndromes. Given the anatomical structures of the vulva, vagina, uterus and uterine appendages, the clinical picture of malformations varies greatly. Methods This S2k-guideline was developed by representative members from different medical specialties and professions as part of the guidelines program of the DGGG, SGGG and OEGGG. The recommendations and statements were developed and voted on using a structured consensus process with neutral moderation. Recommendations This guideline is the first comprehensive summary of female genital malformations from infancy to adulthood which covers clinical examinations, diagnostic workups and treatment options. Additional chapters have been included on complex urogenital malformations, vascular malformations, psychosomatic care, and tumor risk.

Estimated Glomerular Filtration Rates Calculated by New and Old Equations in Children and Adolescents With Type 1 Diabetes-What to Do With the Results?

Background: To apply and evaluate various equations for estimated glomerular filtration rates (eGFR) in a large paediatric type 1 diabetes population and compare the eGFR values with urinary creatinine clearances (UCC) in a subset of patients. Methods: Six eGFR formulae applicable for children and adolescents were used for calculation of eGFR values in 36,782 children/adolescents with type 1 diabetes. Via regression models, factors influencing eGFR values were identified. eGFR values were compared with measured UCC in 549 patients. Spearman correlation coefficients were given to assess the relation of eGFR and UCC values. Bland-Altman-Plots with corresponding linear regression were drawn to evaluate the agreement between eGFR and UCC. Results: eGFR values differed widely depending on the formula used, resulting in a percentage of pathological values <60 mL/min/1.73 m2 up to 8%. Regression models showed age, sex, and duration of diabetes as influencing factors. Microalbuminuria was associated with significantly higher eGFR values for all formulae. In comparison of eGFR with UCC, the highest correlation coefficient was 0.33, the lowest 0.01. Bland-Altman-Plots demonstrated graphically a poor agreement between eGFR and UCC, regardless of the formula used. Conclusions: The broad range of eGFR values indicate that an ideal eGFR formula for children and adolescence with T1D is yet missing. The minimal agreement between measured UCC and eGFR values urges us to be careful in application and interpretation of eGFR values regardless of the formula used.

Mutation analysis of NPHP6/CEP290 in patients with Joubert syndrome and Senior-Løken syndrome.

BACKGROUND: Nephronophthisis (NPHP) is an autosomal recessive cystic kidney disease that constitutes the most common genetic cause of renal failure in the first three decades of life. Using positional cloning, six genes (NPHP1-6) have been identified as mutated in NPHP. In Joubert syndrome (JBTS), NPHP may be associated with cerebellar vermis aplasia/hypoplasia, retinal degeneration and mental retardation. In Senior-Løken syndrome (SLSN), NPHP is associated with retinal degeneration. Recently, mutations in NPHP6/CEP290 were identified as a new cause of JBTS. METHODS: Mutational analysis was performed on a worldwide cohort of 75 families with SLSN, 99 families with JBTS and 21 families with isolated nephronophthisis. RESULTS: Six novel and six known truncating mutations, one known missense mutation and one novel 3 bp pair in-frame deletion were identified in a total of seven families with JBTS, two families with SLSN and one family with isolated NPHP.

Delayed transport of tissue-nonspecific alkaline phosphatase with missense mutations causing hypophosphatasia.

Hypophosphatasia is a rare genetic disease characterized by diminished bone and tooth mineralization due to deficient activity of tissue-nonspecific alkaline phosphatase (TNSALP). The disease is clinically heterogeneous due to different mutations in the TNSALP gene. In order to determine whether mutated TNSALP proteins may be sequestered, degraded, or subjected to delay in their transport to the cell membrane, we built a plasmid expressing a YFP-TNSALP fluorescent fusion protein allowing the observation of cellular localization in live cells by fluorescence confocal microscopy at different time points after transfection. We studied five mutants (c. 571G>A, c. 653T>C, c. 746G>T, c. 1363G>A and c. 1468A>T) exhibiting various levels of in vitro residual enzymatic activity. While the wild-type protein reached the membrane within the first 24h after transfection, the mutants reached the membrane with delays of 24, 48 or 72 h. For all of the tested mutations, accumulation of the mutated proteins, mainly in the Golgi apparatus, was observed. We concluded that reduced ALP activity of these TNSALP mutants results from structural disturbances and delay in membrane anchoring, and not from compromised catalytic activity.

Molecular characterization of HOXA13 polyalanine expansion proteins in hand-foot-genital syndrome.

We report on a father and daughter with hand-foot-genital syndrome (HFGS) with typical skeletal and genitourinary anomalies due to a 14-residue polyalanine expansion in HOXA13. This is the largest (32 residues) polyalanine tract so far described for any polyalanine mutant protein. Polyalanine expansion results in protein misfolding, cytoplasmic aggregation and degradation; however, HOXA13 polyalanine expansions appear to act as loss of function mutations in contrast to gain of function for HOXD13 polyalanine expansions. To address this paradox we examined the cellular consequences of polyalanine expansions on HOXA13 protein using COS cell transfection and immunocytochemistry. HOXA13 polyalanine expansion proteins form cytoplasmic aggregates, and distribution between cytoplasmic aggregates or the nucleus is polyalanine tract size-dependent. Geldanamycin, an Hsp90 inhibitor, reduces the steady-state abundance of all polyalanine-expanded proteins in transfected cells. We also found that wild-type HOXA13 or HOXD13 proteins are sequestered in HOXA13 polyalanine expansion cytoplasmic aggregates. Thus, the difference between HOXA13 polyalanine expansion loss-of-function and HOXD13 polyalanine expansion dominant-negative effect is not the ability to aggregate wild-type group 13 paralogs but perhaps to variation in activities associated with refolding, aggregation or degradation of the proteins.

Novel OCRL1 mutations in patients with the phenotype of Dent disease.

BACKGROUND: Dent disease is an X-linked tubulopathy frequently caused by mutations affecting the voltage-gated chloride channel and chloride/proton antiporter ClC-5. A recent study showed that defects in OCRL1, encoding a phosphatidylinositol 4,5-bisphosphate 5-phosphatase (Ocrl) and usually found mutated in patients with Lowe syndrome, also can provoke a Dent-like phenotype (Dent 2 disease). METHODS: We investigated 20 CLCN5-negative males from 17 families with a phenotype resembling Dent disease for defects in OCRL1. RESULTS: In our complete series of 35 families with a phenotype of Dent disease, a mutation in the OCRL1 gene was detected in 6 kindreds. All were novel frameshift (Q70RfsX88 and T121NfsX122, detected twice) or missense mutations (I257T and R476W). None of our patients had cognitive or behavioral impairment or cataracts, 2 classic hallmarks of Lowe syndrome. All patients had mild increases in lactate dehydrogenase and/or creatine kinase levels, which rarely is observed in CLCN5-positive patients, but frequently found in patients with Lowe syndrome. To explain the phenotypic heterogeneity caused by OCRL1 mutations, we performed extensive data-bank mining and extended reverse-transcriptase polymerase chain reaction analysis, which provided no evidence for yet unknown (tissue-specific) alternative OCRL1 transcripts. CONCLUSION: Mutations in the OCRL1 gene are found in approximately 23% of kindreds with a Dent phenotype. Defective protein sorting/targeting of Ocrl might be the reason for mildly elevated creatine kinase and lactate dehydrogenase serum concentrations in these patients and a clue to suspect Dent disease unrelated to CLCN5 mutations. It remains to be elucidated why the various OCRL1 mutations found in patients with Dent 2 disease do not cause cataracts.

Mutational analysis of the NPHP4 gene in 250 patients with nephronophthisis.

Nephronophthisis (NPH), a recessive cystic kidney disease, is the most frequent genetic cause for end-stage renal disease in the first two decades of life. Mutations in three genes (NPHP1, 2, and 3) were identified as causative. Extrarenal manifestations are known, such as retinitis pigmentosa (Senior-Loken syndrome, SLS) and ocular motor apraxia type Cogan. Recently, we identified a novel gene (NPHP4) as mutated in NPH. To date, a total of only 13 different NPHP4 mutations have been described. To determine the frequency of NPHP4 mutations, we performed mutational analysis by direct sequencing of all 30 NPHP4 exons in 250 different patients with isolated NPH, SLS, or Cogan syndrome ascertained worldwide over 14 years. We identified 23 novel NPHP4 sequence variants in 26/250 different patients (10%). Interestingly, we detected homozygous or compound heterozygous mutations of NPHP4 in only 6/250 different patients (2.4%), but only one heterozygous NPHP4 sequence variant in 20/250 different patients (8%). In the six patients with two NPHP4 mutations, 5/8 mutations (63%) were likely loss-of-function mutations, whereas in the 20 patients with only one sequence variant, only 1/20 (5%) was a likely loss-of-function (i.e., truncating) mutation. We conclude that: i) two recessive mutations in NPHP4 are a rare cause of nephronophthisis; ii) single heterozygous NPHP4 sequence variants are three times more prevalent than two recessive mutations; iii) there is no genotype/phenotype correlation; iv) there must exist further genes causing nephronophthisis, since in 224/250 (90%) patients, no sequence variants in either of the four NPH genes were detected.

Haplotype analysis improves molecular diagnostics of autosomal recessive polycystic kidney disease.

BACKGROUND: Autosomal recessive polycystic kidney disease (ARPKD) is characterized by wide phenotypic variability, ranging from in utero detection with enlarged, echogenic kidneys to an adult presentation with congenital hepatic fibrosis. The ARPKD gene, PKHD1 , covers about 470 kb of DNA (67 exons), and mutation studies have found marked allelic heterogeneity with a high level of novel missense changes and neutral polymorphisms. To improve the prospects for molecular diagnostics and to study the origin of some relatively common mutations, the authors have developed a strategy for improved ARPKD haplotyping. METHODS: A protocol of multiplex PCR and fluorescence genotyping in a single capillary has been developed to assay 7 highly informative simple sequence repeat (SSR) markers that are intragenic or closely flanking PKHD1. RESULTS: Examples in which haplotype analysis, used in combination with mutation screening, improved the utility of molecular diagnostics, especially in families in which just a single PKHD1 mutation has been identified, are illustrated. The new markers also allow screening for larger DNA deletions, detecting unknown consanguinity and exploring the disease mechanism. Analysis of 8 recurring mutations has shown likely common haplotypes for each, and the divergence from the ancestral haplotype, by recombination, can be used to trace the history of the mutation. The common mutation, T36M, was found to have a single European origin, about 1,225 years ago. CONCLUSION: Improved haplotype analysis of ARPKD complements mutation-based diagnostics and helps trace the history of common PKHD1 mutations.

Urinalysis in children and adolescents.

BACKGROUND: Urinalysis is the most commonly performed biochemical test in infancy and early childhood. The urine sample should be correctly obtained, age-specific aspects should be considered, and age-dependent reference values should be used. METHOD: This review is based on a selective literature search in electronic databases, textbooks, and guidelines from Germany and abroad on the acquisition of urine samples and the performance of urinalysis in infancy and early childhood. RESULTS: The timing and mode of acquisition of the urine sample affect the assessment of hematuria, proteinuria, leukocyturia, nitrituria, and the uropathogenic bacterial colony count in the urine culture. Dipstick tests can be used for targeted screening for these features. The test results should be interpreted together with the findings of urine microscopy, the medical history, and the physical examination. Proteinuria should be quantified and differentiated; both of these things can be done either from collected urine or (especially in infants and young children) from a spontaneously voided urine sample, by determination of the protein/creatinine quotient. Orthostatic proteinuria in an adolescent requires no further evaluation or treatment. Hematuria should be characterized as either glomerular or non-glomerular erythrocyturia. Asymptomatic, isolated microhematuria in childhood is not uncommon and often transient; in the absence of a family history, it usually does not require an extensive work-up. Proteinuria combined with hematuria should arouse the suspicion of glomerulonephritis. CONCLUSION: Urinalysis in infancy and early childhood is a simple and informative diagnostic test as long as the urine sample has been obtained properly and the results are interpreted appropriately for this age group.

Evidence of oligogenic inheritance in nephronophthisis.

Nephronophthisis is a recessive cystic renal disease that leads to end-stage renal failure in the first two decades of life. Twenty-five percent of nephronophthisis cases are caused by large homozygous deletions of NPHP1, but six genes responsible for nephronophthisis have been identified. Because oligogenic inheritance has been described for the related Bardet-Biedl syndrome, we evaluated whether mutations in more than one gene may also be detected in cases of nephronophthisis. Because the nephrocystins 1 to 4 are known to interact, we examined patients with nephronophthisis from 94 different families and sequenced all exons of the NPHP1, NPHP2, NPHP3, and NPHP4 genes. In our previous studies involving 44 families, we detected two mutations in one of the NPHP1-4 genes. Here, we detected in six families two mutations in either NPHP1, NPHP3, or NPHP4, and identified a third mutation in one of the other NPHP genes. Furthermore, we found possible digenic disease by detecting one individual who carried one mutation in NPHP2 and a second mutation in NPHP3. Finally, we detected the presence of a single mutation in nine families, suggesting that the second recessive mutation may be in another as yet unidentified NPHP gene. Our findings suggest that oligogenicity may occur in cases of nephronophthisis.