Characteristics of congenital hepatic fibrosis in a large cohort of patients with autosomal recessive polycystic kidney disease.

BACKGROUND & AIMS: Autosomal recessive polycystic kidney disease (ARPKD), the most common ciliopathy of childhood, is characterized by congenital hepatic fibrosis and progressive cystic degeneration of kidneys. We aimed to describe congenital hepatic fibrosis in patients with ARPKD, confirmed by detection of mutations in PKHD1. METHODS: Patients with ARPKD and congenital hepatic fibrosis were evaluated at the National Institutes of Health from 2003 to 2009. We analyzed clinical, molecular, and imaging data from 73 patients (age, 1-56 years; average, 12.7 ± 13.1 years) with kidney and liver involvement (based on clinical, imaging, or biopsy analyses) and mutations in PKHD1. RESULTS: Initial symptoms were liver related in 26% of patients, and others presented with kidney disease. One patient underwent liver and kidney transplantation, and 10 others received kidney transplants. Four presented with cholangitis and one with variceal bleeding. Sixty-nine percent of patients had enlarged left lobes on magnetic resonance imaging, 92% had increased liver echogenicity on ultrasonography, and 65% had splenomegaly. Splenomegaly started early in life; 60% of children younger than 5 years had enlarged spleens. Spleen volume had an inverse correlation with platelet count and prothrombin time but not with serum albumin level. Platelet count was the best predictor of spleen volume (area under the curve of 0.88905), and spleen length corrected for patient's height correlated inversely with platelet count (R(2) = 0.42, P < .0001). Spleen volume did not correlate with renal function or type of PKHD1 mutation. Twenty-two of 31 patients who underwent endoscopy were found to have varices. Five had variceal bleeding, and 2 had portosystemic shunts. Forty-percent had Caroli syndrome, and 30% had an isolated dilated common bile duct. CONCLUSIONS: Platelet count is the best predictor of the severity of portal hypertension, which has early onset but is underdiagnosed in patients with ARPKD. Seventy percent of patients with ARPKD have biliary abnormalities. Kidney and liver disease are independent, and variability in severity is not explainable by type of PKHD1 mutation; ClinicalTrials.gov number, NCT00068224.

Congenital hepatic fibrosis and portal hypertension in autosomal dominant polycystic kidney disease.

OBJECTIVES: Autosomal dominant (ADPKD) and recessive (ARPKD) polycystic kidney diseases are the most common hepatorenal fibrocystic diseases (ciliopathies). Characteristics of liver disease of these disorders are quite different. All of the patients with ARPKD have congenital hepatic fibrosis (CHF) often complicated by portal hypertension. In contrast, typical liver involvement in ADPKD is polycystic liver disease, although rare atypical cases with CHF are reported. Our goal was to describe the characteristics of CHF in ADPKD. PATIENTS AND METHODS: As a part of an intramural study of the National Institutes of Health on ciliopathies (www.clinicaltrials.gov, trial NCT00068224), we evaluated 8 patients from 3 ADPKD families with CHF. We present their clinical, biochemical, imaging, and PKD1 and PKHD1 sequencing results. In addition, we tabulate the characteristics of 15 previously reported patients with ADPKD-CHF from 11 families. RESULTS: In all of the 19 patients with ADPKD-CHF (9 boys, 10 girls), portal hypertension was the main manifestation of CHF; hepatocelllular function was preserved and liver enzymes were largely normal. In all of the 14 families, CHF was not inherited vertically, that is the parents of the index cases had PKD but did not have CHF-suggesting modifier gene(s). Our 3 families had pathogenic mutations in PKD1; sequencing of the PKHD1 gene as a potential modifier did not reveal any mutations. CONCLUSIONS: Characteristics of CHF in ADPKD are similar to CHF in ARPKD. ADPKD-CHF is caused by PKD1 mutations, with probable contribution from modifying gene(s). Given that both boys and girls are affected, these modifier(s) are likely located on autosomal chromosome(s) and less likely X-linked.

Hepatorenal findings in obligate heterozygotes for autosomal recessive polycystic kidney disease.

Autosomal recessive polycystic kidney disease (ARPKD), characterized by progressive cystic degeneration of the kidneys and congenital hepatic fibrosis (CHF), is the most common childhood onset ciliopathy, with an estimated frequency of 1 in 20,000 births. It is caused by mutations in PKHD1. The carrier frequency for ARPKD in the general population is estimated at 1 in 70. Given the recessive inheritance pattern, individuals who are heterozygous for PKHD1 mutations are not expected to have clinical findings. We performed ultrasound (USG) evaluations on 110 parents from 64 independent ARPKD families and identified increased medullary echogenicity in 6 (5.5%) and multiple small liver cysts in 10 parents (9%). All ARPKD parents with these abnormal imaging findings were asymptomatic; kidney and liver function tests were unremarkable. Complete sequencing of PKHD1 in the 16 ARPKD parents with abnormal imaging confirmed the mutation transmitted to the proband, but did not reveal any other pathogenic variants. Our data suggest that carrier status for ARPKD is a predisposition to polycystic liver disease and renal involvement associated with increased medullary echogenicity on USG. Whether some of these individuals become symptomatic as they age remains to be determined.

PKHD1 sequence variations in 78 children and adults with autosomal recessive polycystic kidney disease and congenital hepatic fibrosis.

PKHD1, the gene mutated in autosomal recessive polycystic kidney disease (ARPKD)/congenital hepatic fibrosis (CHF), is an exceptionally large and complicated gene that consists of 86 exons and has a number of alternatively spliced transcripts. Its longest open reading frame contains 67 exons that encode a 4074 amino acid protein called fibrocystin or polyductin. The phenotypes caused by PKHD1 mutations are similarly complicated, ranging from perinatally-fatal PKD to CHF presenting in adulthood with mild kidney disease. To date, more than 300 mutations have been described throughout PKHD1. Most reported cohorts include a large proportion of perinatal-onset ARPKD patients; mutation detection rates vary between 42% and 87%. Here we report PKHD1 sequencing results on 78 ARPKD/CHF patients from 68 families. Differing from previous investigations, our study required survival beyond 6 months and included many adults with a CHF-predominant phenotype. We identified 77 PKHD1 variants (41 novel) including 19 truncating, 55 missense, 2 splice, and 1 small in-frame deletion. Using computer-based prediction tools (GVGD, PolyPhen, SNAP), we achieved a mutation detection rate of 79%, ranging from 63% in the CHF-predominant group to 82% in the remaining families. Prediction of the pathogenicity of missense variants will remain challenging until a functional assay is available. In the meantime, use of PKHD1 sequencing data for clinical decisions requires caution, especially when only novel or rare missense variants are identified.

Fibrocystic disease of liver and pancreas; under-recognized features of the X-linked ciliopathy oral-facial-digital syndrome type 1 (OFD I).

OFD I is an X-linked dominant male-lethal ciliopathy characterized by prominent external features including oral clefts, hamartomas or cysts of the tongue, and digital anomalies. Although these external features are easy to recognize and often lead to diagnosis in early childhood, visceral findings in OFD I, especially the fibrocystic liver and pancreas disease, are under-recognized. In addition, while the occurrence of polycystic kidney disease (PKD) in OFD I is well known, few patients are evaluated and monitored for this complication. We report on two adult females diagnosed with OFD I in infancy, but not evaluated for visceral involvement. In adulthood, they were incidentally found to have severe hypertension and chronic renal insufficiency due to undiagnosed PKD. A pancreatic cystic lesion, also discovered incidentally, was thought to be malignant and led to consideration of major surgery. We present NIH evaluations, including documentation of OFD I mutations, extreme beading of the intrahepatic bile ducts, pancreatic cysts, and tabulate features of reported OFD I cases having hepatic, pancreatic, and renal cystic disease. Liver and pancreas are not routinely evaluated in OFD I patients. Increased awareness and lifelong monitoring of visceral complications, particularly involving the liver, pancreas, and kidney, are essential for timely and accurate treatment.

The redistribution of graduate medical education positions in 2005 failed to boost primary care or rural training.

Graduate medical education (GME), the system to train graduates of medical schools in their chosen specialties, costs the government nearly $13 billion annually, yet there is little accountability in the system for addressing critical physician shortages in specific specialties and geographic areas. Medicare provides the bulk of GME funds, and the Medicare Prescription Drug, Improvement, and Modernization Act of 2003 redistributed nearly 3,000 residency positions among the nation's hospitals, largely in an effort to train more residents in primary care and in rural areas. However, when we analyzed the outcomes of this recent effort, we found that out of 304 hospitals receiving additional positions, only 12 were rural, and they received fewer than 3 percent of all positions redistributed. Although primary care training had net positive growth after redistribution, the relative growth of nonprimary care training was twice as large and diverted would-be primary care physicians to subspecialty training. Thus, the two legislative and regulatory priorities for the redistribution were not met. Future legislation should reevaluate the formulas that determine GME payments and potentially delink them from the hospital prospective payment system. Furthermore, better health care workforce data and analysis are needed to link GME payments to health care workforce needs.

Correlation of kidney function, volume and imaging findings, and PKHD1 mutations in 73 patients with autosomal recessive polycystic kidney disease.

BACKGROUND AND OBJECTIVES: Renal function and imaging findings have not been comprehensively and prospectively characterized in a broad age range of patients with molecularly confirmed autosomal recessive polycystic kidney disease (ARPKD). DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Ninety potential ARPKD patients were examined at the National Institutes of Health Clinical Center. Seventy-three fulfilled clinical diagnostic criteria, had at least one PKHD1 mutation, and were prospectively evaluated using magnetic resonance imaging (MRI), high-resolution ultrasonography (HR-USG), and measures of glomerular and tubular function. RESULTS: Among 31 perinatally symptomatic patients, 25% required renal replacement therapy by age 11 years; among 42 patients who became symptomatic beyond 1 month (nonperinatal), 25% required kidney transplantation by age 32 years. Creatinine clearance (CrCl) for nonperinatal patients (103 +/- 54 ml/min/1.73 m(2)) was greater than for perinatal patients (62 +/- 33) (P = 0.002). Corticomedullary involvement on HR-USG was associated with a significantly worse mean CrCl (61 +/- 32) in comparison with medullary involvement only (131 +/- 46) (P < 0.0001). Among children with enlarged kidneys, volume correlated inversely with function, although with wide variability. Severity of PKHD1 mutations did not determine kidney size or function. In 35% of patients with medullary-only abnormalities, standard ultrasound was normal and the pathology was detectable with HR-USG. CONCLUSIONS: In ARPKD, perinatal presentation and corticomedullary involvement are associated with faster progression of kidney disease. Mild ARPKD is best detected by HR-USG. Considerable variability occurs that is not explained by the type of PKHD1 mutation.