Control of blood pressure in hypertensive children and adolescents assessed by ambulatory blood pressure monitoring.

BACKGROUND: There have been few studies evaluating the control of hypertension (HT) in children. This study aimed to assess the control of HT using ambulatory blood pressure monitoring (ABPM) and to compare the parameters between the uncontrolled HT and controlled HT groups. METHODS: Hypertensive patients aged ≥ 5 years who underwent ABPM to assess the control of HT were enrolled. Demographics, office blood pressure (BP), ABPM, and echocardiographic data were collected. Controlled HT was defined using a BP goal recommended by the 2016 European Society of Hypertension guidelines. RESULTS: There were 108 patients (64.8% males) with a mean age of 14.3 years and 51.9% had primary HT. Controlled HT was detected in 41.1% and 33.3% by office BP and ABPM, respectively. Based on ABPM, there was a greater prevalence of controlled HT in the primary HT than the secondary HT group (44.6% vs. 21.2%, P = 0.01). In the primary HT group, BMI z-score at the last follow-up had a significant decrease in the controlled HT than the uncontrolled HT group (-0.39 vs. 0.01, P = 0.032). Primary HT was negatively associated with uncontrolled HT by ABPM. In addition, ABPM showed greater sensitivity (77.8% vs. 55.8%) and negative predictive value (80.9% vs. 70.8%) to predict LVH than those of office BP measurement. CONCLUSION: Only one-third of patients achieved the BP goal by ABPM and most were in the primary HT group. Weight reduction is an important measure of BP control in patients with primary HT to attenuate the risk of LVH.

Efficacy and Safety of a Dispersible Tablet of GPO-Deferasirox Monotherapy among Children with Transfusion-Dependent Thalassemia and Iron Overload.

The study aimed to determine efficacy and safety of generic deferasirox monotherapy. Deferasirox was administered in transfusion-induced iron overloaded thalassemia. Efficacy was defined as responders and nonresponders by ≤ 15 reduced serum ferritin from baseline. Adverse events were also monitored. Fifty-two patients with mainly Hb E/ß-thalassemia at the mean (SD) age of 8.7 (4.1) years, were enrolled. The mean (SD) daily transfusion iron load was 0.47 (0.1) mg/kg and maximum daily deferasirox was 35.0 (6.2) mg/kg. Altogether, 52, 40 and 18 patients completed the first, second and third years of study, respectively. The median baseline serum ferritin 2,383 ng/mL decreased to 1,478, 1,038 and 1,268 ng/mL at the end of first, second and third years, respectively, with overall response rate at 73.1% (38/52). Patients with baseline serum ferritin >2,500 ng/mL showed a change in serum ferritin higher than those ≤2,500 ng/mL starting from the 9th month of chelation. Adverse events were found in 5 of 52 patients (9.6%) including transaminitis (n = 2), one each of proteinuria, rash and proximal tubular dysfunction which resolved after transient stopping or decreasing the chelation dose. Generic deferasirox was effective and safe among pediatric patients with transfusion-induced iron overloaded thalassemia.

Inadequate blood pressure control demonstrated by ambulatory blood pressure monitoring in pediatric renal transplant recipients.

BACKGROUND: Adequate BP control in RT recipients should not rely only by normal office BP but also on normal 24-hour BP. This study aims to assess adequacy of BP control by ABPM and to assess ABPM parameters associated with LVMI in pediatric RT recipients. MATERIALS AND METHODS: Patients aged 5-20 years who have been followed after RT were enrolled. Demographic data and BP assessed by office and ABPM were collected. Echocardiography was performed to detect LVMI. RESULTS: Thirty RT recipients (18 males) with median age of 15 years (IQR 13-18.5) were included. Among 23 patients who were taking antihypertensive drugs, uncontrolled hypertension was detected in 34.8% and 78.3% by office BP measurement and ABPM, respectively. Thus, the difference in prevalence of uncontrolled hypertension observed by ABPM versus office BP was 43.5%. Those seven patients who were not taking antihypertensive drugs because of normal office BP, four patients (57.1%) had masked hypertension and one patient had elevated BP. Fifteen patients have progression of LVH after RT. Multivariate analysis revealed that age (OR 1.369, 95%CI 0.985-1.904, P-value = 0.062) had a trend to be associated with progression of LVH. Moreover, nighttime systolic BP z-score was significantly correlated with LVMI (r = 0.551, P-value = 0.002). CONCLUSION: The difference in prevalence of uncontrolled hypertension uncovered by ABPM was 43.5%. Nighttime SBP z-score was significantly correlated with LVMI.

Unusual cause of anemia in a child with end-stage renal disease: Questions.

This is the case of a 5-year-old girl diagnosed with end-stage renal disease due to bilateral renal hypoplasia who developed anemia of unknown cause.

Mild recessive mutations in six Fraser syndrome-related genes cause isolated congenital anomalies of the kidney and urinary tract.

Congenital anomalies of the kidney and urinary tract (CAKUT) account for approximately 40% of children with ESRD in the United States. Hitherto, mutations in 23 genes have been described as causing autosomal dominant isolated CAKUT in humans. However, >90% of cases of isolated CAKUT still remain without a molecular diagnosis. Here, we hypothesized that genes mutated in recessive mouse models with the specific CAKUT phenotype of unilateral renal agenesis may also be mutated in humans with isolated CAKUT. We applied next-generation sequencing technology for targeted exon sequencing of 12 recessive murine candidate genes in 574 individuals with isolated CAKUT from 590 families. In 15 of 590 families, we identified recessive mutations in the genes FRAS1, FREM2, GRIP1, FREM1, ITGA8, and GREM1, all of which function in the interaction of the ureteric bud and the metanephric mesenchyme. We show that isolated CAKUT may be caused partially by mutations in recessive genes. Our results also indicate that biallelic missense mutations in the Fraser/MOTA/BNAR spectrum genes cause isolated CAKUT, whereas truncating mutations are found in the multiorgan form of Fraser syndrome. The newly identified recessive biallelic mutations in these six genes represent the molecular cause of isolated CAKUT in 2.5% of the 590 affected families in this study.

Mutations in 12 known dominant disease-causing genes clarify many congenital anomalies of the kidney and urinary tract.

Congenital anomalies of the kidney and urinary tract (CAKUT) account for approximately half of children with chronic kidney disease. CAKUT can be caused by monogenic mutations; however, data are lacking on their frequency. Genetic diagnosis has been hampered by genetic heterogeneity and lack of genotype-phenotype correlation. To determine the percentage of cases with CAKUT that can be explained by mutations in known CAKUT genes, we analyzed the coding exons of the 17 known dominant CAKUT-causing genes in a cohort of 749 individuals from 650 families with CAKUT. The most common phenotypes in this CAKUT cohort were vesicoureteral reflux in 288 patients, renal hypodysplasia in 120 patients, and unilateral renal agenesis in 90 patients. We identified 37 different heterozygous mutations (33 novel) in 12 of the 17 known genes in 47 patients from 41 of the 650 families (6.3%). These mutations include (number of families): BMP7 (1), CDC5L (1), CHD1L (5), EYA1 (3), GATA3 (2), HNF1B (6), PAX2 (5), RET (3), ROBO2 (4), SALL1 (9), SIX2 (1), and SIX5 (1). Furthermore, several mutations previously reported to be disease-causing are most likely benign variants. Thus, in a large cohort over 6% of families with isolated CAKUT are caused by a mutation in 12 of 17 dominant CAKUT genes. Our report represents one of the most in-depth diagnostic studies of monogenic causes of isolated CAKUT in children.

Whole-exome resequencing distinguishes cystic kidney diseases from phenocopies in renal ciliopathies.

Rare single-gene disorders cause chronic disease. However, half of the 6000 recessive single gene causes of disease are still unknown. Because recessive disease genes can illuminate, at least in part, disease pathomechanism, their identification offers direct opportunities for improved clinical management and potentially treatment. Rare diseases comprise the majority of chronic kidney disease (CKD) in children but are notoriously difficult to diagnose. Whole-exome resequencing facilitates identification of recessive disease genes. However, its utility is impeded by the large number of genetic variants detected. We here overcome this limitation by combining homozygosity mapping with whole-exome resequencing in 10 sib pairs with a nephronophthisis-related ciliopathy, which represents the most frequent genetic cause of CKD in the first three decades of life. In 7 of 10 sibships with a histologic or ultrasonographic diagnosis of nephronophthisis-related ciliopathy, we detect the causative gene. In six sibships, we identify mutations of known nephronophthisis-related ciliopathy genes, while in two additional sibships we found mutations in the known CKD-causing genes SLC4A1 and AGXT as phenocopies of nephronophthisis-related ciliopathy. Thus, whole-exome resequencing establishes an efficient, noninvasive approach towards early detection and causation-based diagnosis of rare kidney diseases. This approach can be extended to other rare recessive disorders, thereby providing accurate diagnosis and facilitating the study of disease mechanisms.

Whole-exome resequencing reveals recessive mutations in TRAP1 in individuals with CAKUT and VACTERL association.

Congenital abnormalities of the kidney and urinary tract (CAKUT) account for approximately half of children with chronic kidney disease and they are the most frequent cause of end-stage renal disease in children in the US. However, its genetic etiology remains mostly elusive. VACTERL association is a rare disorder that involves congenital abnormalities in multiple organs including the kidney and urinary tract in up to 60% of the cases. By homozygosity mapping and whole-exome resequencing combined with high-throughput mutation analysis by array-based multiplex PCR and next-generation sequencing, we identified recessive mutations in the gene TNF receptor-associated protein 1 (TRAP1) in two families with isolated CAKUT and three families with VACTERL association. TRAP1 is a heat-shock protein 90-related mitochondrial chaperone possibly involved in antiapoptotic and endoplasmic reticulum stress signaling. Trap1 is expressed in renal epithelia of developing mouse kidney E13.5 and in the kidney of adult rats, most prominently in proximal tubules and in thick medullary ascending limbs of Henle's loop. Thus, we identified mutations in TRAP1 as highly likely causing CAKUT or VACTERL association with CAKUT.

Identification of two novel CAKUT-causing genes by massively parallel exon resequencing of candidate genes in patients with unilateral renal agenesis.

Congenital abnormalities of the kidney and urinary tract (CAKUT) are the most frequent cause of chronic kidney disease in children, accounting for about half of all cases. Although many forms of CAKUT are likely caused by single-gene defects, mutations in only a few genes have been identified. In order to detect new contributing genes we pooled DNA from 20 individuals to amplify all 313 exons of 30 CAKUT candidate genes by PCR analysis and massively parallel exon resequencing. Mutation carriers were identified by Sanger sequencing. We repeated the analysis with 20 new patients to give a total of 29 with unilateral renal agenesis and 11 with other CAKUT phenotypes. Five heterozygous missense mutations were detected in 2 candidate genes (4 mutations in FRAS1 and 1 in FREM2) not previously implicated in non-syndromic CAKUT in humans. All of these mutations were absent from 96 healthy control individuals and had a PolyPhen score over 1.4, predicting possible damaging effects of the mutation on protein function. Recessive truncating mutations in FRAS1 and FREM2 were known to cause Fraser syndrome in humans and mice; however, a phenotype in heterozygous carriers has not been described. Thus, heterozygous missense mutations in FRAS1 and FREM2 cause non-syndromic CAKUT in humans.

Exome sequencing reveals cubilin mutation as a single-gene cause of proteinuria.

In two siblings of consanguineous parents with intermittent nephrotic-range proteinuria, we identified a homozygous deleterious frameshift mutation in the gene CUBN, which encodes cubulin, using exome capture and massively parallel re-sequencing. The mutation segregated with affected members of this family and was absent from 92 healthy individuals, thereby identifying a recessive mutation in CUBN as the single-gene cause of proteinuria in this sibship. Cubulin mutations cause a hereditary form of megaloblastic anemia secondary to vitamin B(12) deficiency, and proteinuria occurs in 50% of cases since cubilin is coreceptor for both the intestinal vitamin B(12)-intrinsic factor complex and the tubular reabsorption of protein in the proximal tubule. In summary, we report successful use of exome capture and massively parallel re-sequencing to identify a rare, single-gene cause of nephropathy.

Clinical Outcomes of Renal Replacement Therapy in Pediatric Acute Kidney Injury: A 10-Year Retrospective Observational Study.

Children with severe acute kidney injury (AKI) have had a high mortality rate despite the use of advanced renal replacement therapy (RRT). This study aims to determine the clinical outcomes and the predictors of survival in pediatric AKI requiring RRT in Thailand. All patients aged 1 month to 18 years with AKI requiring RRT in the Department of Pediatrics, Ramathibodi Hospital from January 1st, 2010 to December 31st, 2019 were enrolled. Clinical and laboratory data were obtained through a medical record review. There were 92 patients with a 45% survival rate. Five factors associated with mortality included multi-organ dysfunction syndrome, presence of sepsis, high pediatric risk of mortality III, use of nephrotoxic drugs, and use of vasopressors. By multivariate analysis, the presence of sepsis and the use of nephrotoxic drugs were independently associated with mortality. Patients with fluid overload ≥10% was associated with poor survival.

Waist-to-height-ratio is associated with sustained hypertension in children and adolescents with high office blood pressure.

Background: Waist-to-height-ratio (WHtR) has been proposed as another indicator for cardiometabolic risk factors including hypertension. Normally, hypertension can be diagnosed in the office setting by detecting high blood pressure for three occasions. However, patients with high office blood pressure may not exhibit high blood pressure outside the office. Ambulatory blood pressure monitoring (ABPM) is a procedure to measure blood pressure over 24-h. Sustained hypertension is characterized as hypertension detected by both office measurement and ABPM. This study aimed to evaluate the performance of WHtR in the diagnosis of sustained hypertension in patients with high office blood pressure. Materials and methods: Demographic data, height, body weight, body mass index (BMI), and waist circumference were retrospectively reviewed in children and adolescents who underwent ABPM due to persistently high office blood pressure. Patients were separated into two groups: a sustained hypertension group and a normal ABPM group. BMI was adjusted to z-score using the WHO Anthroplus software. WHtR was calculated by the formula: waist circumference (cm)/height (m). The performances of different parameters were analyzed using the receiver operating characteristic (ROC) curve and multivariate logistic regression. Results: Sixty patients (63% male) with a mean age of 12.9 ± 3.7 years had persistently high office blood pressure. Twenty-nine (48.3%) had high ambulatory blood pressure parameters so-called "sustained hypertension." The sustained hypertension group had a higher mean BMI z-score (2.32 vs. 1.31, p = 0.01) and a higher mean WHtR (57.7 vs. 49.2 cm/m, p < 0.001) than those of the normal ABPM group. For the diagnosis of sustained hypertension, the ROC analysis revealed that WHtR had a greater area under the ROC curve (AUC) than that of BMI z-score (0.772 vs. 0.723). WHtR remained associated with sustained hypertension (OR 1.2, 95% CI 1.022-1.408, p = 0.026) after adjusting for age, gender, and BMI z-score. Conclusions: Apart from being a more user-friendly metric, WHtR tended to outperform BMI z-score in predicting sustained hypertension in children and adolescents with persistently high office blood pressure.

Mapping of a new locus for congenital anomalies of the kidney and urinary tract on chromosome 8q24.

BACKGROUND: Congenital anomalies of the kidney and urinary tract (CAKUT) account for the majority of end-stage renal disease in children (50%). Previous studies have mapped autosomal dominant loci for CAKUT. We here report a genome-wide search for linkage in a large pedigree of Somalian descent containing eight affected individuals with a non-syndromic form of CAKUT. METHODS: Clinical data and blood samples were obtained from a Somalian family with eight individuals with CAKUT including high-grade vesicoureteral reflux and unilateral renal agenesis. Total genome search for linkage was performed using a 50K SNP Affymetric DNA microarray. As neither parent is affected, the results of the SNP array were analysed under recessive models of inheritance, with and without the assumption of consanguinity. RESULTS: Using the non-consanguineous recessive model, a new gene locus (CAKUT1) for CAKUT was mapped to chromosome 8q24 with a significant maximum parametric Logarithm of the ODDs (LOD) score (LOD(max)) of 4.2. Recombinations were observed in two patients defining a critical genetic interval of 2.5 Mb physical distance flanked by markers SNP_A-1740062 and SNP_A-1653225. CONCLUSION: We have thus identified a new non-syndromic recessive gene locus for CAKUT (CAKUT1) on chromosome 8q24. The identification of the disease-causing gene will provide further insights into the pathogenesis of urinary tract malformations and mechanisms of renal development.

Nineteen novel NPHS1 mutations in a worldwide cohort of patients with congenital nephrotic syndrome (CNS).

BACKGROUND: Recessive mutations in the NPHS1 gene encoding nephrin account for approximately 40% of infants with congenital nephrotic syndrome (CNS). CNS is defined as steroid-resistant nephrotic syndrome (SRNS) within the first 90 days of life. Currently, more than 119 different mutations of NPHS1 have been published affecting most exons. METHODS: We here performed mutational analysis of NPHS1 in a worldwide cohort of 67 children from 62 different families with CNS. RESULTS: We found bi-allelic mutations in 36 of the 62 families (58%) confirming in a worldwide cohort that about one-half of CNS is caused by NPHS1 mutations. In 26 families, mutations were homozygous, and in 10, they were compound heterozygous. In an additional nine patients from eight families, only one heterozygous mutation was detected. We detected 37 different mutations. Nineteen of the 37 were novel mutations (approximately 51.4%), including 11 missense mutations, 4 splice-site mutations, 3 nonsense mutations and 1 small deletion. In an additional patient with later manifestation, we discovered two further novel mutations, including the first one affecting a glycosylation site of nephrin. CONCLUSIONS: Our data hereby expand the spectrum of known mutations by 17.6%. Surprisingly, out of the two siblings with the homozygous novel mutation L587R in NPHS1, only one developed nephrotic syndrome before the age of 90 days, while the other one did not manifest until the age of 2 years. Both siblings also unexpectedly experienced an episode of partial remission upon steroid treatment.

Outcomes of Empirical Antimicrobial Therapy for Pediatric Community-onset Febrile Urinary Tract Infection in the Era of Increasing Antimicrobial Resistance.

BACKGROUND: Urinary tract infection (UTI) is a common cause of fever in children. Despite the increasing numbers of extended-spectrum beta-lactamase-producing organisms in the community, the empirical therapy of choice is still third-generation cephalosporins. This study was performed to investigate whether inappropriate empirical therapy (IAT) of community-onset UTI results in adverse clinical outcomes. METHODS: We retrospectively studied a cohort of pediatric patients with first-episode community-onset UTI caused by Escherichia coli, Klebsiella pneumoniae and Proteus spp. at Ramathibodi Hospital from 2011 to 2017. The patients were classified into IAT and appropriate empirical therapy (AT) groups. Medical records were reviewed to assess clinical outcomes. RESULTS: One hundred fifty-one eligible patients were enrolled in this study. The most common causative organism was E. coli (88.8% and 96.2% in the AT and IAT groups, respectively). Among the causative organisms, 19.8% were extended-spectrum beta-lactamase-producing organisms. There was no significant difference in clinical failure, microbiologic failure, relapse or time to defervescence between the 2 groups. No patients in either group developed sepsis after receiving empirical therapy. However, the length of hospital stay was significantly longer in the IAT than AT group [4.00 (4.50-6.00) vs. 7.00 (5.00-11.25) days, respectively; P = 0.000]. CONCLUSIONS: No significant difference in treatment outcomes was found between pediatric patients receiving AT and IAT for the treatment of UTI. In the era of increasing antimicrobial resistance, third-generation cephalosporins may still be a good choice as an empirical antimicrobial for children diagnosed with community-onset UTI.

Henoch-Schönlein purpura from vasculitis to intestinal perforation: A case report and literature review.

Henoch-Schönlein purpura (HSP) is generally a self-limited vasculitis disease and has a good prognosis. We report a 4-year-old Thai boy who presented with palpable purpura, abdominal colicky pain, seizure, and eventually developed intestinal ischemia and perforation despite adequate treatment, including corticosteroid and intravenous immunoglobulin therapy. Imaging modalities, including ultrasonography and contrast-enhanced computed tomography, could not detect intestinal ischemia prior to perforation. In this patient, we also postulated that vasculitis-induced mucosal ischemia was a cause of the ulcer, leading to intestinal perforation, and high-dose corticosteroid could have been a contributing factor since the histopathology revealed depletion of lymphoid follicles. Intestinal perforation in HSP is rare, but life-threatening. Close monitoring and thorough clinical evaluation are essential to detect bowel ischemia before perforation, particularly in HSP patients who have hematochezia, persistent localized abdominal tenderness and guarding. In highly suspicious cases, exploratory laparotomy may be needed for the definite diagnosis and prevention of further complications.

Rapid detection of monogenic causes of childhood-onset steroid-resistant nephrotic syndrome.

BACKGROUND AND OBJECTIVES: In steroid-resistant nephrotic syndrome (SRNS), >21 single-gene causes are known. However, mutation analysis of all known SRNS genes is time and cost intensive. This report describes a new high-throughput method of mutation analysis using a PCR-based microfluidic technology that allows rapid simultaneous mutation analysis of 21 single-gene causes of SRNS in a large number of individuals. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This study screened individuals with SRNS; samples were submitted for mutation analysis from international sources between 1996 and 2012. For proof of principle, a pilot cohort of 48 individuals who harbored known mutations in known SRNS genes was evaluated. After improvements to the method, 48 individuals with an unknown cause of SRNS were then examined in a subsequent diagnostic study. The analysis included 16 recessive SRNS genes and 5 dominant SRNS genes. A 10-fold primer multiplexing was applied, allowing PCR-based amplification of 474 amplicons in 21 genes for 48 DNA samples simultaneously. Forty-eight individuals were indexed in a barcode PCR, and high-throughput sequencing was performed. All disease-causing variants were confirmed via Sanger sequencing. RESULTS: The pilot study identified the genetic cause of disease in 42 of 48 (87.5%) of the affected individuals. The diagnostic study detected the genetic cause of disease in 16 of 48 (33%) of the affected individuals with a previously unknown cause of SRNS. Seven novel disease-causing mutations in PLCE1 (n=5), NPHS1 (n=1), and LAMB2 (n=1) were identified in <3 weeks. Use of this method could reduce costs to 1/29th of the cost of Sanger sequencing. CONCLUSION: This highly parallel approach allows rapid (<3 weeks) mutation analysis of 21 genes known to cause SRNS at a greatly reduced cost (1/29th) compared with traditional mutation analysis techniques. It detects mutations in about 33% of childhood-onset SRNS cases.

ARHGDIA mutations cause nephrotic syndrome via defective RHO GTPase signaling.

Nephrotic syndrome (NS) is divided into steroid-sensitive (SSNS) and -resistant (SRNS) variants. SRNS causes end-stage kidney disease, which cannot be cured. While the disease mechanisms of NS are not well understood, genetic mapping studies suggest a multitude of unknown single-gene causes. We combined homozygosity mapping with whole-exome resequencing and identified an ARHGDIA mutation that causes SRNS. We demonstrated that ARHGDIA is in a complex with RHO GTPases and is prominently expressed in podocytes of rat glomeruli. ARHGDIA mutations (R120X and G173V) from individuals with SRNS abrogated interaction with RHO GTPases and increased active GTP-bound RAC1 and CDC42, but not RHOA, indicating that RAC1 and CDC42 are more relevant to the pathogenesis of this SRNS variant than RHOA. Moreover, the mutations enhanced migration of cultured human podocytes; however, enhanced migration was reversed by treatment with RAC1 inhibitors. The nephrotic phenotype was recapitulated in arhgdia-deficient zebrafish. RAC1 inhibitors were partially effective in ameliorating arhgdia-associated defects. These findings identify a single-gene cause of NS and reveal that RHO GTPase signaling is a pathogenic mediator of SRNS.

COQ6 mutations in human patients produce nephrotic syndrome with sensorineural deafness.

Steroid-resistant nephrotic syndrome (SRNS) is a frequent cause of end-stage renal failure. Identification of single-gene causes of SRNS has generated some insights into its pathogenesis; however, additional genes and disease mechanisms remain obscure, and SRNS continues to be treatment refractory. Here we have identified 6 different mutations in coenzyme Q10 biosynthesis monooxygenase 6 (COQ6) in 13 individuals from 7 families by homozygosity mapping. Each mutation was linked to early-onset SRNS with sensorineural deafness. The deleterious effects of these human COQ6 mutations were validated by their lack of complementation in coq6-deficient yeast. Furthermore, knockdown of Coq6 in podocyte cell lines and coq6 in zebrafish embryos caused apoptosis that was partially reversed by coenzyme Q10 treatment. In rats, COQ6 was located within cell processes and the Golgi apparatus of renal glomerular podocytes and in stria vascularis cells of the inner ear, consistent with an oto-renal disease phenotype. These data suggest that coenzyme Q10-related forms of SRNS and hearing loss can be molecularly identified and potentially treated.