Homozygosity mapping identifies a bile acid biosynthetic defect in an adult with cirrhosis of unknown etiology

Integrated Analysis of Single-Cell and Bulk RNA Sequencing Reveals HSD3B7 as a Prognostic Biomarker and Potential Therapeutic Target in ccRCC

Clear cell renal cell carcinoma (ccRCC) is the most common kidney malignancy, with a poor prognosis for advanced-stage patients. Identifying key biomarkers involved in tumor progression is crucial for improving treatment outcomes. In this study, we employed an integrated approach combining single-cell RNA sequencing (scRNA-seq) and bulk RNA sequencing (bulk RNA-seq) to identify biomarkers associated with ccRCC progression and prognosis. Single-cell transcriptomic data were obtained from publicly available datasets, and genes related to tumor progression were screened using Monocle2. Bulk RNA-seq data for ccRCC were retrieved from The Cancer Genome Atlas (TCGA) and integrated with scRNA-seq data to explore tumor heterogeneity. We identified 3 beta-hydroxy steroid dehydrogenase type 7 (HSD3B7) as a candidate biomarker for ccRCC, associated with poor overall survival, disease-specific survival, and progression-free interval. Elevated HSD3B7 expression correlated with aggressive clinical features such as advanced TNM stages, histologic grades, and metastasis. Functional studies demonstrated that HSD3B7 promotes cell proliferation, migration, and invasion in vitro, while its silencing significantly inhibits tumor growth in vivo. Our findings reveal that HSD3B7 is a novel biomarker for ccRCC, providing insights into its role in tumor progression and potential as a target for therapy. This study highlights the value of integrating scRNA-seq and bulk RNA-seq data to uncover key regulators of tumor biology and lays the foundation for developing personalized therapeutic strategies for ccRCC patients.

EASL Clinical Practice Guidelines on genetic cholestatic liver diseases

Genetic cholestatic liver diseases are caused by (often rare) mutations in a multitude of different genes. While these diseases differ in pathobiology, clinical presentation and prognosis, they do have several commonalities due to their cholestatic nature. These Clinical Practice Guidelines (CPGs) offer a general approach to genetic testing and management of cholestatic pruritus, while exploring diagnostic and treatment approaches for a subset of genetic cholestatic liver diseases in depth. An expert panel appointed by the European Association for the Study of the Liver has created recommendations regarding diagnosis and treatment, based on the best evidence currently available in the fields of paediatric and adult hepatology, as well as genetics. The management of these diseases generally takes place in a tertiary referral centre, in order to provide up-to-date approaches and expertise. These CPGs are intended to support hepatologists (for paediatric and adult patients), residents and other healthcare professionals involved in the management of these patients with concrete recommendations based on currently available evidence or, if not available, on expert opinion.

Navigating cholestasis: identifying inborn errors of bile acid metabolism for precision diagnosis

Inborn errors of bile acid metabolism (IEBAM) cause cholestasis during the neonatal period, and 8 types of IEBAM have been reported to date. IEBAM accounts for approximately 2% of cases of cholestasis of unknown cause. As only 10 patients have been identified in Japan, IEBAM presents diagnostic challenges due to the similarity of clinical symptoms with biliary atresia, thus necessitating precise differentiation to avoid unnecessary invasive procedures. Laboratory tests in IEBAM are characterized by normal γ-glutamyltransferase (GGT) and serum total bile acid (STBA) levels despite the presence of cholestasis; therefore, measuring STBA and GGT is essential to distinguishing biliary atresia from IEBAM. With suspected IEBAM, liquid chromatography-mass spectrometry (LC/MS) analysis of urinary bile acids is needed to optimize diagnostic and therapeutic efficacy and avoid open cholangiography and initiate treatment for primary bile acids such as cholic acid or chenodeoxycholic acid. This prospective report aims to increase awareness of IEBAM by highlighting the characteristics of general blood test and bile acid profiles from LC/MS analyses of blood, urine, and stool samples.

Androgen Metabolism and Response in Prostate Cancer Anti-Androgen Therapy Resistance

All aspects of prostate cancer evolution are closely related to androgen levels and the status of the androgen receptor (AR). Almost all treatments target androgen metabolism pathways and AR, from castration-sensitive prostate cancer (CSPC) to castration-resistant prostate cancer (CRPC). Alterations in androgen metabolism and its response are one of the main reasons for prostate cancer drug resistance. In this review, we will introduce androgen metabolism, including how the androgen was synthesized, consumed, and responded to in healthy people and prostate cancer patients, and discuss how these alterations in androgen metabolism contribute to the resistance to anti-androgen therapy.

Cholestatic liver diseases of genetic etiology: Advances and controversies

With the application of modern investigative technologies, cholestatic liver diseases of genetic etiology are increasingly identified as the root cause of previously designated "idiopathic" adult and pediatric liver diseases. Here, we review advances in the field enhanced by a deeper understanding of the phenotypes associated with specific gene defects that lead to cholestatic liver diseases. There are evolving areas for clinicians in the current era specifically regarding the role for biopsy and opportunities for a "sequencing first" approach. Risk stratification based on the severity of the genetic defect holds promise to guide the decision to pursue primary liver transplantation versus medical therapy or nontransplant surgery, as well as early screening for HCC. In the present era, the expanding toolbox of recently approved therapies for hepatologists has real potential to help many of our patients with genetic causes of cholestasis. In addition, there are promising agents under study in the pipeline. Relevant to the current era, there are still gaps in knowledge of causation and pathogenesis and lack of fully accepted biomarkers of disease progression and pruritus. We discuss strategies to overcome the challenges of genotype-phenotype correlation and draw attention to the extrahepatic manifestations of these diseases. Finally, with attention to identifying causes and treatments of genetic cholestatic disorders, we anticipate a vibrant future of this dynamic field which builds upon current and future therapies, real-world evaluations of individual and combined therapeutics, and the potential incorporation of effective gene editing and gene additive technologies.

Prognosis and clinical characteristics of patients with 3β-hydroxy-Δ5-C27-steroid dehydrogenase deficiency diagnosed in childhood: A systematic review of the literature

OBJECTIVES

3β-hydroxy-Δ5-C27-steroid dehydrogenase deficiency is a rare autosomal recessive condition. So far fewer than 100 cases have been reported and the factors affecting the prognosis are not yet established. The objective of this study is to explore a possible prediction of the outcome of this rare condition.

METHODS

This review was undertaken and reported in accordance with the preferred reporting items for systematic review and meta-analyses guidelines. Demographics, clinical features, gene data, treatment strategies and prognoses at the last follow-up were extracted and summarized. Patients were divided into 2 groups (alive with native liver and liver transplantation/died). Risk factors for the different clinical features were identified.

RESULTS

87 patients that were taken from 7 case reports and 9 case series were included. 38 (38/63, 63.0%) of them presented initial symptoms when they were younger than 1 month and 55 (55/63, 87.3%) less than 1 year. There is a larger proportion of patients younger than 1 month or 1 year at the age of symptom onset in the liver transplantation /died group than patients in alive with the native liver group. The majority of patients (53/62, 85.5%) were diagnosed before the age of 5 year. In all cases, 65 (predicted) pathogenic variants have been identified. Over 70% of patients carried an HSD3B7 variant on exon 1, 4, 5 or 6. 71 (81.6%) were alive at the last follow-up, 16 (18.4%) underwent liver transplantation or died. No significance was found between the group alive with native liver and group liver transplantation /died.

CONCLUSION

Age of onset of the symptoms may be a potential factor that determines the outcome of patients with 3β-HSD deficiency, patients presented with symptoms and signs at an age younger than 1 month or even 1 year may have a worse prognosis. Since there is no difference between clinical outcome and zygosity of gene mutation, we recommend a further study about any possible relationship between mutation site and clinical characteristics or prognosis.

Genetic spectrum and clinical characteristics of 3β-hydroxy-Δ5-C27-steroid oxidoreductase (HSD3B7) deficiency in China

BACKGROUND

Biallelic variants in HSD3B7 cause 3β-hydroxy-Δ5-C27-steroid oxidoreductase (HSD3B7) deficiency, a life-threatening but treatable liver disease. The goal of this study was to obtain detailed information on the correlation between the genotype and phenotype of HSD3B7 deficiency and to report on responses to primary bile acid therapy.

METHODS

The medical records of a cohort of 39 unrelated patients with genetically and biochemically confirmed HSD3B7 deficiency were examined to determine whether there exist genotype-phenotype relationships in this bile acid synthesis disorder.

RESULTS

In all, 34 of the 44 variants identified in HSD3B7 were novel. A total of 32 patients presented early with neonatal cholestasis, and 7 presented after 1-year of age with liver failure (n = 1), liver cirrhosis (n = 3), cholestasis (n = 1), renal cysts and abnormal liver biochemistries (n = 1), and coagulopathy from vitamin K1 deficiency and abnormal liver biochemistries (n = 1). Renal lesions, including renal cysts, renal stones, calcium deposition and renal enlargement were observed in 10 of 35 patients. Thirty-three patients were treated with oral chenodeoxycholic acid (CDCA) resulting in normalization of liver biochemistries in 24, while 2 showed a significant clinical improvement, and 7 underwent liver transplantation or died. Remarkably, renal lesions in 6 patients resolved after CDCA treatment, or liver transplantation. There were no significant correlations between genotype and clinical outcomes.

CONCLUSIONS

In what is the largest cohort of patients with HSD3B7 deficiency thus far studied, renal lesions were a notable clinical feature of HSD3B7 deficiency and these were resolved with suppression of atypical bile acids by oral CDCA administration.

Use of a Comprehensive 66-Gene Cholestasis Sequencing Panel in 2171 Cholestatic Infants, Children, and Young Adults

OBJECTIVES

Cholestasis is caused by a wide variety of etiologies, often genetic in origin. Broad overlap in clinical presentations, particularly in newborns, renders prioritizing diagnostic investigations challenging. In this setting, a timely, comprehensive assessment using a multigene panel by a clinical diagnostic laboratory would likely prove useful. We summarize initial findings from a testing program designed to discover genetic causes of cholestasis.

METHODS

A neonatal/adult sequencing panel containing 66 genes (originally 57; nine added March 2017) relevant to cholestasis was used. A broad range of eligible patients were enrolled with current/history of cholestasis without an identified cause, or unexplained chronic liver disease. DNA sequencing utilized a custom-designed capture library, and variants were classified and reported as benign, likely benign, variant of unknown significance (VOUS), likely pathogenic (LP), or pathogenic (P), according to the clinical interpretation workflow at EGL Genetics (Tucker, GA).

RESULTS

A total of 2433 samples were submitted between February 2016 and December 2017; 2171 results were reported. Median turnaround time was 21 days. Results from the 2171 subjects (57% <1 year old) included 583 P variants, 79 LP variants, and 3117 VOUS; 166 P/LP variants and 415 VOUS were novel. The panel's overall diagnostic yield was 12% (n = 265/2171) representing 32 genes. The top five genetic diagnoses for the group, in order: JAG1 + NOTCH2 (Alagille syndrome), ABCB11, SERPINA1, ABCB4, and POLG.

CONCLUSIONS

These findings support the utility of comprehensive rapid multigene testing in diagnosing cholestasis and highlight the evolving understanding of genetic variants contributing to the pathogenesis of cholestasis.

Cryptogenic cirrhosis: Old and new perspectives in the era of molecular and genomic medicine

Cryptogenic cirrhosis (CC) is defined as cirrhosis of unknown etiology despite extensive clinical, laboratory and pathologic work-up, and constitutes approximately 5-10% of all cirrhosis cases. Histologic examination can provide important clues and help identify the potential etiology of CC. Most CC cases can still be classified into four histologic patterns: hepatitic, steatotic, biliary, and patternless (bland). The use of genetic testing has significantly improved diagnostic ability and treatment, especially in pediatric patients with acute and chronic liver diseases. More recently, whole exome sequencing has been used for identifying genetic alterations that lead to a diagnosis in adults with liver disease of unknown etiology. Recent advances in genomic analysis has allowed the unraveling of the underlying etiology in a subset of CC cases, and also helped identify new disorders. Providing a diagnosis for these patients has several important implications for treatment, possible genetic counseling, and transplant eligibility. However, detailed clinical and histologic characterization of the patients still remains an important part of the CC work-up, since clinicopathologic and genomic correlation is crucial in making a diagnosis, or in some cases, discovery of a new entity. This article summarizes the main histologic findings that can be observed in CC cases, potential causes of CC, and recent advances in the field.

Δ4-3-oxosteroid-5β-reductase deficiency: Responses to oral bile acid therapy and long-term outcomes

BACKGROUND

Disorders of primary bile acid synthesis may be life-threatening if undiagnosed, or not treated with primary bile acid replacement therapy. To date, there are few reports on the management and follow-up of patients with Δ4-3-oxosteroid 5β-reductase (AKR1D1) deficiency. We hypothesized that a retrospective analysis of the responses to oral bile acid replacement therapy with chenodeoxycholic acid (CDCA) in patients with this bile acid synthesis disorder will increase our understanding of the disease progression and permit evaluation of this treatment regimen as an alternative to the Food and Drug Administration (FDA) approved drug cholic acid, which is currently unavailable in China.

AIM

To evaluate the therapeutic responses of patients with AKR1D1 deficiency to oral bile acid therapy, specifically CDCA.

METHODS

Twelve patients with AKR1D1 deficiency, confirmed by fast atom bombardment ionization-mass spectrometry analysis of urine and by gene sequencing for mutations in AKR1D1, were treated with differing doses of CDCA or ursodeoxycholic acid (UDCA). The clinical and biochemical responses to therapy were monitored over a period ranging 0.5-6.4 years. Dose adjustment, to optimize the therapeutic dose, was based on changes in serum biochemistry parameters, notably liver function tests, and suppression of the urinary levels of atypical hepatotoxic 3-oxo-Δ4-bile acids measured by mass spectrometry.

RESULTS

Physical examination, serum biochemistry parameters, and sonographic findings improved in all 12 patients during bile acid therapy, except one who underwent liver transplantation. Urine bile acid analysis confirmed a significant reduction in atypical hepatotoxic 3-oxo-Δ4 bile acids concomitant with clinical and biochemical improvements in those patients treated with CDCA. UDCA was ineffective in down-regulating endogenous bile acid synthesis as evidenced from the inability to suppress the urinary excretion of atypical 3-oxo-Δ4-bile acids. The dose of CDCA required for optimal clinical and biochemical responses varied from 5.5-10 mg/kg per day among patients based on maximum suppression of the atypical bile acids and improvement in serum biochemistry parameters, and careful titration of the dose was necessary to avoid side effects from CDCA.

CONCLUSION

The primary bile acid CDCA is effective in treating AKR1D1 deficiency but the therapeutic dose requires individualized optimization. UDCA is not recommended for long-term management.

Inborn Errors of Bile Acid Metabolism

Inborn errors of bile acid metabolism are rare causes of neonatal cholestasis and liver disease in older children and adults. The diagnosis should be considered in the context of hyperbilirubinemia with normal serum bile acids and made by urinary liquid secondary ionization mass spectrometry or DNA testing. Cholic acid is an effective treatment of most single-enzyme defects and patients with Zellweger spectrum disorder with liver disease.

Cholic acid for primary bile acid synthesis defects: a life-saving therapy allowing a favorable outcome in adulthood

Background

Oral cholic acid (CA) replacement has been shown to be an effective therapy in children with primary bile acid synthesis defects, which are rare and severe genetic liver diseases. To date there has been no report of the effects of this therapy in children reaching adulthood. The aim of the study was to evaluate the long-term effectiveness and safety of CA therapy.

Methods

Fifteen patients with either 3β-hydroxy-Δ⁵-C₂₇-steroid oxidoreductase (3β-HSD) (n = 13) or Δ⁴–3-oxosteroid 5β-reductase (Δ⁴–3-oxo-R) (n = 2) deficiency confirmed by mass spectrometry and gene sequencing received oral CA and were followed prospectively.

Results

The median age at last follow-up and the median time of follow-up with treatment were 24.3 years (range: 15.3–37.2) and 21.4 years (range: 14.6–24.1), respectively. At last evaluation, physical examination findings and blood laboratory test results were normal in all patients. Liver sonograms were normal in most patients. Mean daily CA dose was 6.9 mg/kg of body weight. Mass spectrometry analysis of urine showed that excretion of the atypical metabolites remained low or traces in amount with CA therapy. Liver fibrosis scored in liver biopsies or assessed by elastography in 14 patients, after 10 to 24 years with CA therapy, showed a marked improvement with disappearance of cirrhosis (median score < F1; range: F0-F2). CA was well tolerated in all patients, including five women having 10 uneventful pregnancies during treatment.

Conclusions

Oral CA therapy is a safe and effective long-term treatment of 3β-HSD and Δ⁴–3-oxo-R deficiencies and allows affected children to reach adulthood in good health condition without the need for a liver transplantation.

Bile Acid Synthesis Disorders in Arabs: A 10-year Screening Study

OBJECTIVES

Early diagnosis of bile acid synthesis disorders (BASDs) is important because, untreated, these conditions can be fatal. Our objectives were to screen children with cholestasis or unexplained liver disease for BASD and in those with confirmed BASD to evaluate the effectiveness of cholic acid therapy.

METHODS

A routine serum total bile acid measurement was performed on children with cholestasis, liver cirrhosis, and liver failure. Patients were screened for BASD by fast atom bombardment ionization-mass spectrometry (FAB-MS) analysis of urine, and molecular analysis confirmed diagnosis. Treatment response to oral cholic acid (10-15 mg/kg bw/day) was assessed from liver function tests and fat-soluble vitamin levels. FAB-MS analysis of urine was used to monitor compliance and biochemical response.

RESULTS

Between 2007 and 2016, 626 patients were evaluated; 450 with infantile cholestasis. Fifteen cases of BASD were diagnosed: 12 presented with infantile cholestasis (2.7%, 7 boys), an 8-year-old boy presented with cirrhosis, and two 18-month-old boys presented with hepatomegaly and rickets. Eleven were caused by 3β-hydroxy-Δ-C27-steroid oxidoreductase dehydrogenase deficiency, 3 from Δ-3-oxosteroid 5β-reductase deficiency, and 1 had Zellweger spectrum disorder. In all but 1, serum total bile acids were normal or low. With cholic acid therapy, 10 are alive and healthy with their native liver. Liver failure developed in 3 infants despite therapy; 2 died and 1 underwent liver transplantation.

CONCLUSIONS

BASDs are rare but treatable causes of metabolic liver disease in Saudi Arabia. BASD should be considered in infants with cholestasis and low or normal serum total bile acid concentrations.

Atypical clinical presentation and successful treatment with oral cholic acid of a child with defective bile acid synthesis due to a novel mutation in the HSD3B7 gene

We report definitive diagnosis and effective treatment with oral cholic acid in one Italian male child affected by 3β-hydroxy-Δ⁵-C²⁷-steroid dehydrogenase (3β-HSD) deficiency. He presented with failure to thrive, hepatomegaly and multiple cystic images in kidneys; no biochemical evidence of cholestasis. Large amounts of bile acid metabolites was detected in urine by fast atom bombardment ionization mass spectrometry (FAB-MS). HSDH3B7 gene analysis identified one mutation in intron 4, at nucleotide 432, G>A substitution that has never been reported before.The replacement therapy with oral cholic acid started early after the diagnosis and is still ongoing. Three years later hepatomegaly is no longer evident, liver function is normal and the child is growing regularly. In our experience, clinical features of 3β-HSD deficiency can be very poor and even cholestasis can lack at diagnosis. Early replacement therapy with cholic acid is safe and leads to clinical and biochemical control of the disease.

Oral Cholic Acid Is Efficacious and Well Tolerated in Patients With Bile Acid Synthesis and Zellweger Spectrum Disorders

OBJECTIVES

Patients with bile acid synthesis disorders (BASDs) due to single enzyme defects (SEDs) or Zellweger spectrum disorders (ZSDs) accumulate hepatotoxic atypical bile acids resulting in potentially fatal progressive liver disease. We evaluated the efficacy and safety of oral cholic acid in patients with BASD.

METHODS

In this phase 3, open-label, single-arm, nonrandomized, noncomparative study conducted over 18 years, patients were administered cholic acid orally 10 to 15 mg · kg · day. The primary efficacy variables were changes from pre- to post-treatment in atypical urinary bile acids, liver chemistries (serum aspartate aminotransferase, alanine aminotransferase), and height and weight. Additional efficacy variables included changes in serum bilirubin and liver histology.

RESULTS

Of the 85 enrolled patients (63 with SED and 22 with ZSD), 79 received at least 1 dose of study medication; 70 patients (50 with SED and 20 with ZSD) were included in the modified intent-to-treat dataset. Cholic acid significantly improved urine bile acid metabolite scores (P < 0.0001) and serum aspartate aminotransferase and alanine aminotransferase (P < 0.0001) in patients with SED and ZSD. Cholic acid also improved height and weight percentiles in both groups, but only the change in weight was significant (P < 0.05). Serum direct bilirubin decreased significantly post-treatment (P < 0.001) in the intent-to-treat population, and liver biopsies showed either stable findings or histologic improvement in all parameters except bridging fibrosis. The overall safety profile of cholic acid was favorable, with no study drug-related serious adverse events or drug-related deaths reported.

CONCLUSIONS

Oral cholic acid is a safe, efficacious, and well-tolerated treatment for BASD due to SED and ZSD.

Elucidation of the complex metabolic profile of cerebrospinal fluid using an untargeted biochemical profiling assay

We sought to determine the molecular composition of human cerebrospinal fluid (CSF) and identify the biochemical pathways represented in CSF to understand the potential for untargeted screening of inborn errors of metabolism (IEMs). Biochemical profiles for each sample were obtained using an integrated metabolomics workflow comprised of four chromatographic techniques followed by mass spectrometry. Secondarily, we wanted to compare the biochemical profile of CSF with those of plasma and urine within the integrated mass spectrometric-based metabolomic workflow. Three sample types, CSF (N=30), urine (N=40) and EDTA plasma (N=31), were analyzed from retrospectively collected pediatric cohorts of equivalent age and gender characteristics. We identified 435 biochemicals in CSF representing numerous biological and chemical/structural families. Sixty-three percent (273 of 435) of the biochemicals detected in CSF also were detected in urine and plasma, another 32% (140 of 435) were detected in either plasma or urine, and 5% (22 of 435) were detected only in CSF. Analyses of several metabolites showed agreement between clinically useful assays and the metabolomics approach. An additional set of CSF and plasma samples collected from the same patient revealed correlation between several biochemicals detected in paired samples. Finally, analysis of CSF from a pediatric case with dihydropteridine reductase (DHPR) deficiency demonstrated the utility of untargeted global metabolic phenotyping as a broad assessment to screen samples from patients with undifferentiated phenotypes. The results indicate a single CSF sample processed with an integrated metabolomics workflow can be used to identify a large breadth of biochemicals that could be useful for identifying disrupted metabolic patterns associated with IEMs.

Attempt to Determine the Prevalence of Two Inborn Errors of Primary Bile Acid Synthesis: Results of a European Survey

OBJECTIVE

Inborn errors of primary bile acid (BA) synthesis are genetic cholestatic disorders leading to accumulation of atypical BA with deficiency of normal BA. Unless treated with primary BA, chronic liver disease usually progresses to cirrhosis and liver failure before adulthood. We sought to determine the prevalence of 2 common disorders, 3β-hydroxy-Δ-C27-steroid dehydrogenase (3β-HSD) and Δ-3-oxosteroid-5β-reductase (Δ-3-oxoR) deficiencies and to describe current diagnostic and treatment strategies among different European paediatric hepatology centres.

METHODS

A total of 52 clinical paediatric centres were approached and 39 centres in 21 countries agreed to participate in the Web-based survey. The survey comprised questions regarding general information, number of cases, diagnostic, and therapeutic management.

RESULTS

Seventeen centres located in 11 countries reported patients with inborn errors in primary BA synthesis, 22 centres never had cases diagnosed. In total, we could identify 63 patients; 55 with 3β-HSD and 8 with Δ-3-oxoR deficiency in 21 countries. The minimum estimated combined prevalence of these diseases was 1.13 cases per 10 million (0.99 and 0.14 for 3β-HSD and Δ-3-oxoR deficiencies, respectively). The surveyed colleagues indicated their main challenges to be the rarity of diseases and the lack of convenient laboratory facilities nearby.

CONCLUSION

We have identified the largest cohort of patients with 3β-HSD or Δ-3-oxoR deficiency described so far. These diseases are likely underdiagnosed mainly due to unawareness of their existence and the lack of laboratory facilities.

Metabolic Liver Disease: When to Suspect and How to Diagnose?

Metabolic liver diseases are still considered by many as a 'rare' diagnosis, though scenario has definitely changed in recent times. With recent advances and wider availablility of newer techniques, many of these are now amenable to diagnosis and optimum management. Though the logistics involved are still out of reach of a significant proportion of our population, a stepwise and methodological approach with simple diagnostic tests can help point towards a probable diagnosis (with resultant directed investigations), helping to avoid unnecessary and costly workup. This review focuses on diagnostic protocol-based approach to common metabolic liver diseases encountered frequently in pediatric hepatology.

Tandem Mass Spectrometric Determination of Atypical 3β-Hydroxy-Δ5-Bile Acids in Patients with 3β-Hydroxy-Δ5-C27-Steroid Oxidoreductase Deficiency: Application to Diagnosis and Monitoring of Bile Acid Therapeutic Response

BACKGROUND

3β-Hydroxy-Δ5-C27-steroid oxidoreductase (HSD3B7) deficiency, a progressive cholestatic liver disease, is the most common genetic defect in bile acid synthesis. Early diagnosis is important because patients respond to oral primary bile acid therapy, which targets the negative feedback regulation for bile acid synthesis to reduce the production of hepatotoxic 3β-hydroxy-Δ5-bile acids. These atypical bile acids are highly labile and difficult to accurately measure, yet a method for accurate determination of 3β-hydroxy-Δ5-bile acid sulfates is critical for dose titration and monitoring response to therapy.

METHODS

We describe a electrospray ionization LC-MS/MS method for the direct measurement of atypical 3β-hydroxy-Δ5-bile acid sulfates in urine from patients with HSD3B7 deficiency that overcomes the deficiencies of previously used GC-MS methods.

RESULTS

Separation of sulfated 3β-hydroxy-Δ5-bile acids was achieved by reversed-phase HPLC in a 12-min analytical run. The mean (SE) urinary concentration of the total 3β-sulfated-Δ5-cholenoic acids in patients with HSD3B7 deficiency was 4650 (1711) μmol/L, approximately 1000-fold higher than in noncholestatic and cholestatic patients with intact primary bile acid synthesis. GC-MS was not reliable for measuring 3β-hydroxy-Δ5-bile acid sulfates; however, direct analysis of urine by fast atom bombardment mass spectrometry yielded meaningful semiquantitative assessment of urinary excretion.

CONCLUSIONS

The tandem mass spectrometry method described here for the measurement of 3β-hydroxy-Δ5-bile acid sulfates in urine can be applied to the diagnosis and accurate monitoring of responses to primary bile acid therapy in HSD3B7 patients.

Molecular cloning, expression analysis and developmental changes in ovarian follicles of goose 3β-hydroxysteroid dehydrogenase 1

The enzyme 3β-hydroxysteroid dehydrogenase/isomerase1 (3βHSD1) can catalyse the conversion of pregnenolone to progesterone in the △4-3-ketosteroid metabolic pathway. The aim of the present study was to clone 3βHSD1 and to determine whether this enzyme in the follicular wall has an effect on yolk progesterone in geese (Anser cygnoides). A putative coding sequence of 3βHSD1, which was 1134 nucleotides in length, was successfully obtained by using reverse transcription polymerase chain reaction (RT–PCR). A comparison of the deduced amino acid sequence with chicken, quail, zebra finch, cattle, horse, pig, human and mouse 3βHSD1 showed 89.7%, 88.4%, 87.3%, 55.6%, 54.0%, 53.5%, 55.3% and 52.9% similarity, respectively. The detection of 3βHSD1 mRNA levels in several tissues by quantitative real-time PCR showed that the highest level of 3βHSD1 was in the adrenal gland, followed by the ovary, which indicated that the gene we obtained was the adrenal gland/gonad-specific one. We measured the level of 3βHSD1 mRNA in the follicular wall and determined the concentration of progesterone in the yolk of these ovarian follicles; the concentration of progesterone in the yolk had a pattern of expression similar to that of 3βHSD1 in the follicular wall during follicular development. This result suggests that the expression of 3βHSD1 in the follicular wall may be a main factor that contributes to the accumulation of yolk progesterone.

Growth and development of a new subspecialty: pediatric hepatology

Several major forces converged to catalyze the formal emergence of a body of knowledge and an organized focus on disorders of the liver in early life. Attendant to the development of a focused clinical subspecialty the pace of patient- and laboratory-based research in the field quickened in parallel to decipher the consequences of genetic or metabolic aberrations on immature liver structure and function. The key research observations that catalyzed the emergence and subsequent rapid growth of Pediatric Hepatology include: (1) an understanding of the dynamic events occurring during hepatobiliary development and the importance of these physiologic variables that occur during liver maturation; (2) the recognition of the unique nature of inherited and acquired liver diseases that affect infants and children-such as biliary atresia and Reye's syndrome; and (3) redefinition of the once obscure inherited intrahepatic cholestatic diseases of the liver, which, in turn, provided insight into normal and abnormal hepatobiliary physiology. The clinical advances were highlighted by the development of specific approaches to the diagnosis and management of liver disease in infants and children, including both liver transplantation and nontransplant treatment options. These seminal events led to the expansion of the workforce, creating a critical mass consisting of individuals with focused, specialized skills and techniques. In-depth expertise allowed more accurate diagnosis and highly effective treatment strategies for advanced hepatobiliary disease in children. The demand for pediatric clinicians with experience in advanced hepatology allowed sub-sub-specialization to flourish. Continued maturation of the field led to definition of hepatology-focused curricular elements and educational content for Pediatric Gastroenterology training programs, and subsequently the development of program requirements for those who wished to acquire additional training in Pediatric Hepatology. A significant rite of passage was marked by the election of pediatric hepatologists to leadership positions in the American Association for the Study of Liver Diseases (AASLD). Further validation of the field occurred with approval of the petition for establishing a Certificate of Added Qualification in Transplant Hepatology by the American Board of Pediatrics. Here I relate my perspective on the history of the advances in our field and the contributions of many of the clinicians and scientists whose efforts led to the development of focused clinical, research, and training programs that improved the care of children with diseases of the liver.

Hunting human disease genes: lessons from the past, challenges for the future

The concept that a specific alteration in an individual’s DNA can result in disease is central to our notion of molecular medicine. The molecular basis of more than 3,500 Mendelian disorders has now been identified. In contrast, the identification of genes for common disease has been much more challenging. We discuss historical and contemporary approaches to disease gene identification, focusing on novel opportunities such as the use of population extremes and the identification of rare variants. While our ability to sequence DNA has advanced dramatically, assigning function to a given sequence change remains a major challenge, highlighting the need for both bioinformatics and functional approaches to appropriately interpret these data. We review progress in mapping and identifying human disease genes and discuss future challenges and opportunities for the field.