Early cirrhosis in survivors with Jeune thoracic dystrophy

New mutations in DYNC2H1 and WDR60 genes revealed by whole-exome sequencing in two unrelated Sardinian families with Jeune asphyxiating thoracic dystrophy

Jeune asphyxiating thoracic dystrophy (JATD; Jeune syndrome, MIM 208500) is a rare autosomal recessive chondrodysplasia, phenotypically overlapping with short-rib polydactyly syndromes (SRPS). JATD typical hallmarks include skeletal abnormalities such as narrow chest, shortened ribs, limbs shortened bones, extra fingers and toes (polydactyly), as well as extraskeletal manifestations (renal, liver and retinal disease). To date, disease-causing mutations have been found in several genes, highlighting a marked genetic heterogeneity that prevents a molecular diagnosis of the disease in most families. Here, we report the results of whole-exome sequencing (WES) carried out in four JATD cases, belonging to three unrelated families of Sardinian origin. The exome analysis allowed to identify mutations not previously reported in the DYNC2H1 (MIM 603297) and WDR60 (MIM 615462) genes, both codifying for ciliary intraflagellar transport components whose mutations are known to cause Jeune syndrome.

Ciliopathies: an expanding disease spectrum

Ciliopathies comprise a group of disorders associated with genetic mutations encoding defective proteins, which result in either abnormal formation or function of cilia. As cilia are a component of almost all vertebrate cells, cilia dysfunction can manifest as a constellation of features that include characteristically, retinal degeneration, renal disease and cerebral anomalies. Additional manifestations include congenital fibrocystic diseases of the liver, diabetes, obesity and skeletal dysplasias. Ciliopathic features have been associated with mutations in over 40 genes to date. However, with over 1,000 polypeptides currently identified within the ciliary proteome, several other disorders associated with this constellation of clinical features will likely be ascribed to mutations in other ciliary genes. The mechanisms underlying many of the disease phenotypes associated with ciliary dysfunction have yet to be fully elucidated. Several elegant studies have crucially demonstrated the dynamic ciliary localisation of components of the Hedgehog and Wnt signalling pathways during signal transduction. Given the critical role of the cilium in transducing "outside-in" signals, it is not surprising therefore, that the disease phenotypes consequent to ciliary dysfunction are a manifestation of aberrant signal transduction. Further investigation is now needed to explore the developmental and physiological roles of aberrant signal transduction in the manifestation of ciliopathy phenotypes. Utilisation of conditional and inducible murine models to delete or overexpress individual ciliary genes in a spatiotemporal and organ/cell-specific manner should help clarify some of the functional roles of ciliary proteins in the manifestation of phenotypic features.

Making sense of cilia in disease: the human ciliopathies

Ubiquitous in nature, cilia and flagella comprise nearly identical structures with similar functions. The most obvious example of the latter is motility: driving movement of the organism or particle flow across the epithelial surface in fixed structures. In vertebrates, such motile cilia are evident in the respiratory epithelia, ependyma, and oviducts. For over a century, non-motile cilia have been observed on the surface of most vertebrate cells but until recently their function has eluded us. Gathering evidence now points to critical roles for the mono-cilium in sensing the extracellular environment, and perturbation of this function gives rise to a predictable panoply of clinical problems. We review the common clinical phenotypes associated with ciliopathies and interrogate Online Mendelian Inheritance in Man (OMIM) to compile a comprehensive list of putative disorders in which ciliary dysfunction may play a role.

Jeune syndrome: description of 13 cases and a proposal for follow-up protocol

Jeune syndrome (asphyxiating thoracic dystrophy, ATD) is a rare autosomal recessive skeletal dysplasia characterized by a small, narrow chest and variable limb shortness with a considerable neonatal mortality as a result of respiratory distress. Renal, hepatic, pancreatic and ocular complications may occur later in life. We describe 13 cases with ages ranging from 9 months to 22 years. Most patients experienced respiratory problems in the first years of their life, three died, one experienced renal complications, and one had hepatic problems. With age, the thoracic malformation tends to become less pronounced and the respiratory problems decrease. The prognosis of ATD seems better than described in literature and in our opinion this justifies long term intensive treatment in the first years. We also propose a follow-up protocol for patients with ATD.

Liver and kidney disease in ciliopathies

Hepatorenal fibrocystic diseases (HRFCDs) are among the most common inherited human disorders. The discovery that proteins defective in the autosomal dominant and recessive polycystic kidney diseases (ADPKD and ARPKD) localize to the primary cilia and the recognition of the role these organelles play in the pathogenesis of HRFCDs led to the term "ciliopathies." While ADPKD and ARPKD are the most common ciliopathies associated with both liver and kidney disease, variable degrees of renal and/or hepatic involvement occur in many other ciliopathies, including Joubert, Bardet-Biedl, Meckel-Gruber, and oral-facial-digital syndromes. The ductal plate malformation (DPM), a developmental abnormality of the portobiliary system, is the basis of the liver disease in ciliopathies that manifest congenital hepatic fibrosis (CHF), Caroli syndrome (CS), and polycystic liver disease (PLD). Hepatocellular function remains relatively preserved in ciliopathy-associated liver diseases. The major morbidity associated with CHF is portal hypertension (PH), often leading to esophageal varices and hypersplenism. In addition, CD predisposes to recurrent cholangitis. PLD is not typically associated with PH, but may result in complications due to mass effects. The kidney pathology in ciliopathies ranges from non-functional cystic dysplastic kidneys to an isolated urinary concentration defect; the disorders contributing to this pathology, in addition to ADPKD and ARPKD, include nephronophithisis (NPHP), glomerulocystic kidney disease and medullary sponge kidneys. Decreased urinary concentration ability, resulting in polyuria and polydypsia, is the first and most common renal symptom in ciliopathies. While the majority of ADPKD, ARPKD, and NPHP patients require renal transplantation, the frequency and rate of progression to renal failure varies considerably in other ciliopathies. This review focuses on the kidney and liver disease found in the different ciliopathies.

Spine deformities in rare congenital syndromes: clinical issues

STUDY DESIGN

A focused review of the literature with regard to the important system abnormalities of patients with spinal deformities associated with exotic congenital syndromes with additional data from the author's own experience in assessment of patients with rare syndromes treated for thoracic insufficiency syndrome.

OBJECTIVES

The objectives of this study are to emphasize important medical considerations that influence the choice of surgical treatment of spinal deformity in patients with exotic congenital syndromes and point out preoperative strategies that reduce treatment morbidity and mortality of these patients.

SUMMARY OF BACKGROUND DATA

Individual experience is limited in the treatment of spine abnormality in rare exotic syndromes and the medical aspects of these syndromes that may impact spinal treatment are seldom discussed in detail in the orthopedic literature. For a successful outcome in the treatment of spinal deformity in these unique patients, a working knowledge of the unique pitfalls in their medical care is necessary in order to avoid morbidity and mortality during their treatment.

METHODS

The literature was reviewed for 6 exotic congenital syndromes with known or unreported spinal abnormalities and the author's personal 22-years experience of the treatment of thoracic insufficiency syndrome in the relevant congenital syndromes was summarized.

RESULTS

Children with Marfan syndrome and spinal deformity may have serious cardiac abnormalities. Spontaneous dissection of the aortic root is a clear danger and patients should be monitored by serial echocardiograms. Prophylactic cardiac surgery may be necessary before spinal surgery is to be performed. Patients with Jeune syndrome have a high rate of proximal cervical stenosis and should undergo screening with cervical spine films at birth. Significant stenosis or instability may require decompression and cervical-occipital fusion. Arthrogryposis may be associated with a severe scoliosis and jaw contracture may make intubation difficult. Larsen syndrome may have early onset scoliosis that is very rigid and requires early intervention. Cervical kyphosis and subluxation may be lethal in these patients and screening radiographs are important. Upper airway abnormalities are an anesthesia concern. Jarcho-Levin syndrome is a thoracic volume depletion deformity due to shortness of the thorax, either a spondylocostal dysostosis variant or spondylothoracic dysplasia. The former has a chaotic congenital scoliosis with varied combination of missing and fused ribs. Although spondylocostal dysostosis has a benign reputation in the literature for respiratory complications, respiratory insufficiency is nevertheless common and 1 death is known from respiratory failure. Spondylothoracic dysplasia seldom has significant scoliosis, but has a mortality rate approaching 50% from respiratory complications due to thoracic insufficiency syndrome. In spite of severe restrictive respiratory disease, adult survivors of spondylothoracic dysplasia appear to do well clinically for unknown reasons. Cerebrocostomandibular syndrome has scoliosis, micrognathia, and thoracic insufficiency syndrome, due to an "implosion" deformity of the thorax from congenital pseudarthrosis of the posterior ribs.

CONCLUSION

For optimal patient care, it is necessary to have a clear understanding of exotic congenital syndromes and how they may impact on both the presentation of spinal deformity and the response to treatment, as well as how they may introduce additional morbidity into standard treatment plans. It is clear that with this understanding that preoperative strategies can be employed to enhance the safety of spinal treatment for these unique children.

Liver transplantation in Ellis-van Creveld syndrome: a case report

This case represents a rare association of Ellis-van Creveld (EvC) syndrome, a chondroectodermal disorder, with congenital paucity of bile ducts. Sequential liver biopsies during the patient's childhood demonstrated progressive fibrosis that can occur in other chondrodysplastic malformations. However, this EvC case is the first report to demonstrate paucity of intra-hepatic bile ducts progressing to cirrhosis and subsequently requiring transplant.

Retransplantation in a patient with type 2 Jeune's syndrome

Jeune's syndrome is a rare inherited cause of kidney failure associated with skeletal dysplasia in children. We report the case of a 20-year-old girl who had Jeune's syndrome type 2 and underwent a second kidney transplant after failure of the first allograft. The patient had 16 years of good allograft function with the first transplant and successfully received a second cadaveric graft.

Familial asphyxiating thoracic dysplasia: clinical variability and impact of improved neonatal intensive care

We describe 3 siblings with asphyxiating thoracic dysplasia whose neonatal symptoms range from mild respiratory distress to asphyxia and death. The youngest sibling received aggressive modern respiratory intensive care, survived, and at 2 years showed no respiratory symptoms. Improved neonatal intensive care has implications for clinical decision making and genetic counseling.

Jeune syndrome and liver disease: report of three cases treated with ursodeoxycholic acid

Three children with Jeune syndrome (asphyxiating thoracic dystrophy) had clinical and laboratory evidence of liver disease. In two patients the disease evolved to biliary cirrhosis, whereas in the third it was recognized when extensive fibrosis was developing. In the three patients, treatment with ursodeoxycholic acid appeared to control the progression of the hepatic dysfunction.