Isolated congenital hepatic fibrosis associated with TMEM67 mutations: report of a new genotype-phenotype relationship

Refining Kidney Survival in 383 Genetically Characterized Patients With Nephronophthisis

Introduction

Nephronophthisis (NPH) comprises a group of rare disorders accounting for up to 10% of end-stage kidney disease (ESKD) in children. Prediction of kidney prognosis poses a major challenge. We assessed differences in kidney survival, impact of variant type, and the association of clinical characteristics with declining kidney function.

Methods

Data was obtained from 3 independent sources, namely the network for early onset cystic kidney diseases clinical registry (n = 105), an online survey sent out to the European Reference Network for Rare Kidney Diseases (n = 60), and a literature search (n = 218).

Results

A total of 383 individuals were available for analysis: 116 NPHP1, 101 NPHP3, 81 NPHP4 and 85 NPHP11/TMEM67 patients. Kidney survival differed between the 4 cohorts with a highly variable median age at onset of ESKD as follows: NPHP3, 4.0 years (interquartile range 0.3–12.0); NPHP1, 13.5 years (interquartile range 10.5–16.5); NPHP4, 16.0 years (interquartile range 11.0–25.0); and NPHP11/TMEM67, 19.0 years (interquartile range 8.7–28.0). Kidney survival was significantly associated with the underlying variant type for NPHP1, NPHP3, and NPHP4. Multivariate analysis for the NPHP1 cohort revealed growth retardation (hazard ratio 3.5) and angiotensin-converting enzyme inhibitor (ACEI) treatment (hazard ratio 2.8) as 2 independent factors associated with an earlier onset of ESKD, whereas arterial hypertension was linked to an accelerated glomerular filtration rate (GFR) decline.

Conclusion

The presented data will enable clinicians to better estimate kidney prognosis of distinct patients with NPH and thereby allow personalized counseling.

Elderly onset congenital hepatic fibrosis with portal hypertension diagnosed after recurrent cholangitis: a case report

Congenital hepatic fibrosis is a rare autosomal recessive disorder caused by ductal plate malformation that can manifest as hepatic fibrosis alone or as a component in various fibropolycystic diseases including renal involvement. It is often diagnosed early in life, presenting with ascites and esophageal variceal bleeding due to non-cirrhotic portal hypertension. Here, we report a rare case of congenital hepatic fibrosis with portal hypertension diagnosed at an advanced age. A 78-year-old woman with a 6 history of recurrent cholangitis experienced abdominal distension. Imaging revealed ascites and esophageal varices. Histopathologic analysis of the liver revealed the fibrous expansion of portal tracts accompanying increased bile ducts with irregular contours in the portal area. These characteristic findings are consistent with the diagnosis of congenital hepatic fibrosis. The present case showed an extremely unique clinical course, because she did not develop any associated renal abnormalities or any disease-related symptoms until old age. Because of the variability of this disease, the slowly progressive type may be difficult to diagnose and cause non-cirrhotic portal hypertension even in the elderly. Although an unusual clinical course may suggest the presence of the disease, timely histologic assessment is crucial for the definitive diagnosis of congenital hepatic fibrosis.

Congenital Hepatic Fibrosis in Children and Adults: Clinical Manifestations, Management, and Outcome-Case Series and Literature Review

Background

Congenital hepatic fibrosis is a hereditary fibropolycystic disease caused by ductal plate malformation. It is characterized by portal hypertension, but the manifestations, management, and outcome vary in children and adults. To raise awareness of medical staff, we have comprehensively compared the clinical features of congenital hepatic fibrosis between children and adults.

Methods

We retrospectively enrolled all patients diagnosed with congenital hepatic fibrosis at the Huashan Hospital from August 2015 to August 2017 and analyzed their familial, clinical, laboratory, imaging, treatment, and follow-up data in detail. In addition, we reviewed cases with congenital hepatic fibrosis reported in the past 20 years in China and analyzed them according to the patients' age.

Results

A total of eight patients were diagnosed with congenital hepatic fibrosis in the study, including four children and four adults. The onset age of the children, who suffered from severe complications of portal hypertension and needed liver transplantation, ranged from 1 to 15 years old. The disorder developed in adults aged 26 to 60 years old. Three adults complained of recurrent abnormal liver function at the onset of illness, and they mainly received conservative treatments. The literature review included 30 children and 33 adults. In comparison, hepatomegaly was more common in children than in adults (57% vs. 21%, p = 0.004). Malformation of kidneys and bile duct abnormalities were common, and multisystem involvement included eyes, other digestive organs, and genital and central nervous systems.

Conclusions

Serious complications of portal hypertension developed in children requiring liver transplantation, while adults often had mild-to-moderate liver injuries upon onset. Adults with CHF varied a lot in clinical manifestations. Multiorgan involvement and unusual course are helpful to make a diagnosis. Timely histological assessment by liver biopsy and multidisciplinary cooperation are crucial for definitive diagnosis and early intervention.

Novel compound heterozygous TMEM67 variants in a Vietnamese family with Joubert syndrome: a case report

Background

Joubert syndrome is a genetically heterogeneous autosomal recessive ciliopathy characterized by the combination of hypoplasia/aplasia of the cerebellar vermis, thickened and elongated superior cerebellar peduncles and a deep interpeduncular fossa, known as “molar tooth sign” associated with hypotonia, respiratory control disturbances and abnormal eye movements. To date, pathogenic variants in over 35 genes are known to cause autosomal recessive Joubert Syndrome, while one gene is associated with X-linked recessive inheritance.

Case presentation

We describe here a non-consanguineous Vietnamese family with Joubert syndrome, a fetus and 10-year-old developmentally delayed boy. Ultrasonography showed ventriculomegaly at 26 + 6 weeks of gestation in the fetus. The 10-year-old-boy was diagnosed with cerebral palsy of unknown origin. Clinical physical examination at the age of 10, he showed clinical features of Joubert syndrome including typical facial dysmorphism, ataxia, severe psychomotor delay, oculomotor apraxia and molar tooth sign on brain MRI. Whole exome sequencing analysis identified a novel compound heterozygous c.725A > G p.Asn242Ser and c.313-3 T > G p.Lys105Valfs*16 TMEM67 variant in the proband and the affected fetus. These two variants were inherited from each parent and confirmed by Sanger sequencing. The variant c.725A > G p.Asn242Ser was previously documented in patients with JS, the novel splice-site c.313-3 T > G p.Lys105Valfs*16 TMEM67 variant produced an aberrant transcript with the loss of four nucleotides of exon 03.

Conclusion

This study confirms the diagnosis of Joubert syndrome in a Vietnamese family and expands the mutational spectrum of TMEM67 sequence variations. We also highlight the importance of molecular approaches to unravel underlying mechanisms of human genetic disorders. Early precise diagnosis could help provide further accurate genetic counseling for recurrence-risk assessment, future diagnostic option, management as well as treatment guidance for rare disorders.

Biallelic variants in the ciliary gene TMEM67 cause RHYNS syndrome

A rare syndrome was first described in 1997 in a 17-year-old male patient presenting with Retinitis pigmentosa, HYpopituitarism, Nephronophthisis and Skeletal dysplasia (RHYNS). In the single reported familial case, two brothers were affected, arguing for X-linked or recessive mode of inheritance. Up to now, the underlying genetic basis of RHYNS syndrome remains unknown. Here we applied whole-exome sequencing in the originally described family with RHYNS to identify compound heterozygous variants in the ciliary gene TMEM67. Sanger sequencing confirmed a paternally inherited nonsense c.622A > T, p.(Arg208*) and a maternally inherited missense variant c.1289A > G, p.(Asp430Gly), which perturbs the correct splicing of exon 13. Overall, TMEM67 showed one of the widest clinical continuum observed in ciliopathies ranging from early lethality to adults with liver fibrosis. Our findings extend the spectrum of phenotypes/syndromes resulting from biallelic TMEM67 variants to now eight distinguishable clinical conditions including RHYNS syndrome.

Unexplained cholestasis in adults and adolescents: diagnostic benefit of genetic examination

OBJECTIVES

A few adult and adolescent patients with even severe cholestatic liver disease remain unexplained after standard diagnostic work-up. We studied the value of genetic examination in such patients and developed a panel of eight genes with known cholestatic associations.

MATERIALS AND METHODS

Thirty-three patients with unexplained cholestasis despite a thorough clinical work-up were examined for sequence variations in the coding regions of the ABCB4, ABCB11, ABCC2, ABCG5, ATP8B1, JAG1, NOTCH2, and UGT1A1 genes and the promoter region of UGT1A1 by massive parallel sequencing of DNA extracted from whole blood. Hepatologists and clinical geneticists evaluated the causal potential of genetic variants.

RESULTS

In 9/33 patients (27%), we identified genetic variants as a certain causal factor and in further 9/33 (27%) variants as a possible contributing factor. In most cases, a detailed family history was necessary to establish the importance of genetic variants. Genetic causes were identified in 6/13 women (46%) with intrahepatic cholestasis during pregnancy and persisting abnormal biochemistry after delivery.

CONCLUSIONS

Our study suggests that a small number of well-known genetic variants are involved in at least 27-54% of patients with unexplained cholestasis. An expanded panel will likely explain more cases. This motivates genetic testing of these patients. Genetic testing, however, cannot stand alone but should be combined with a clinical genetic work-up in collaboration between hepatologists and clinical geneticists.