Recurrent familial intrahepatic cholestasis in the Faeroe Islands. Phenotypic heterogeneity but genetic homogeneity

Recurrent familial intrahepatic cholestasis is an autosomal recessive disorder characterized by episodes of severe pruritus and jaundice lasting for weeks to months without extrahepatic bile duct obstruction. Symptom-free intervals may last for months to years, and chronic liver damage does not develop. We recently studied four of the five patients from the Faeroe Islands described by us 30 years ago (one had recently died) and an additional five patients that were identified after the initial report. The episodes of cholestasis were more frequent and severe in patients with early onset, but tended to reduce in frequency with age. The youngest patient, aged 25 years, who had had 16 episodes each lasting about 6 months, had a liver transplant after which no further episodes were recorded (1 year after surgery). Signs of chronic liver disease were absent in all patients. The FIC1 gene was investigated for mutations in the surviving patients. A single mutation (I661T) was found on both chromosomes in all nine patients, indicating that they are genetically identical for the disease-causing defect. Nevertheless, considerable differences among patients were observed clinically.     

Mutations in the COCH gene are a frequent cause of autosomal dominant progressive cochleo-vestibular dysfunction, but not of Meniere's disease

The COCH gene is the only gene identified in man that causes autosomal dominantly inherited hearing loss associated with vestibular dysfunction. The condition is rare and only five mutations have been reported worldwide. All affected families showed a similar progressive hearing loss and vestibular dysfunction. Since Meniere's disease-like symptoms have also been described in some families, it was suggested that COCH mutations might be present in some patients diagnosed with Meniere's disease. In this study, using a Japanese population, we performed a COCH mutation analysis in 23 patients from independent families with autosomal dominant hearing impairment, four of whom reported vestibular symptoms, and also in 20 Meniere's patients. While a new point mutation, A119 T, was found in a patient with autosomal dominant hearing loss and vestibular symptoms, no mutations were found in the Meniere's patients. Like all other previously identified COCH mutations, the mutation identified here is a missense mutation located in the FCH domain of the protein. The current mutation is located in close spatial proximity to W117, in which a mutation (W117R) had previously been associated with autosomal dominant hearing loss. Model building suggests that, like the W117R mutation, the A119 T mutation does not affect the structural integrity of the FCH domain, but may interfere with the interaction with a yet unknown binding partner. We conclude that mutations in the COCH gene are responsible for a significant fraction of patients with autosomal dominantly inherited hearing loss accompanied by vestibular symptoms, but not for dominant hearing loss without vestibular dysfunction, or sporadic Meniere's disease.     

Mutations in the mineralocorticoid receptor gene cause autosomal dominant pseudohypoaldosteronism type I

We report intractable meningitis and intracranial abscess in a diabetic patient, arising from sphenoid sinusitis and osteomyelitis caused by Candida species. Magnetic resonance images (MRI) revealed the sinusitis and osteomyelitis with direct invasion of the sellar region and clivus, subsequently intracranial abscess.     

Mutations in the sulonylurea receptor gene are associated with familial hyperinsulinism in Ashkenazi Jews

Familial hyperinsulinism (HI) is a disorder of pancreatic beta-cell function characterized by persistent hyperinsulinism despite severe hypoglycemia. To define the molecular genetic basis of HI in Ashkenazi Jews, 25 probands were screened for mutations in the sulfonylurea receptor (SUR1) gene by single-strand conformation polymorphism (SSCP) analysis of genomic DNA and subsequent nucleotide sequence analyses. Two common mutations were identified: (I) a novel in-frame deletion of three nucleotides (nt) in exon 34, resulting in deletion of the codon for F1388 (delta F1388) and (II) a previously described g-->a transition at position-9 of the 3' splice site of intron 32 (designated 3992-9g-->a). Together, these mutations are associated with 88% of the HI chromosomes of the patients studied. 86Rb+ efflux measurements of COSm6 cells co-expressing Kir6.2 and either wild-type or delta F1388 SUR1 revealed that the F1388 mutation abolished ATP-sensitive potassium channel (KATP) activity in intact cells. Extended haplotype analyses indicated that the delta F1388 mutation was associated with a single specific haplotype whereas the 3992-9g-->a mutation was primarily associated with a single haplotype but also occurred in the context of several other different haplotypes. These data suggest that HI in Ashkenazi Jews is predominantly associated with mutations in the SUR1 gene and provide evidence for the existence of at least two founder HI chromosomes in this population.     

Mutations in the CLCN5 gene in Japanese patients with familial idiopathic low-molecular-weight proteinuria

Familial idiopathic low-molecular-weight proteinuria (FILMWP) is a renal proximal tubulopathy that occurs predominantly in males. FILMWP is characterized by mild proteinuria consisting of low-molecular-weight proteinuria, aminoaciduria and relatively conserved renal function, but without rickets. To determine whether FILMWP is related to the CLCN5 gene, which is responsible for Dent's disease and two related disorders, we analyzed the CLCN5 gene from four Japanese families with FILMWP. We identified two novel mutations: one was a single base insertion at codon 520 serine in exon 10 and the other was a single base deletion at codon 403 tyrosine in exon 8. These mutations caused a shift in the reading frame, resulting in synthesis of truncated CLC5 proteins that lacked 220 (29%) and 314 (42%) amino acids, respectively. These mutations were demonstrated to cosegregate with the disease in two families, respectively. We conclude that the CLCN5 gene is responsible for this proximal renal tubulopathy in some Japanese families and that FILMWP is possibly a variant of Dent's disease.     

Mutations in the gene for cardiac myosin-binding protein C and late-onset familial hypertrophic cardiomyopathy

BACKGROUND: Mutations in the gene for cardiac myosin-binding protein C account for approximately 15 percent of cases of familial hypertrophic cardiomyopathy. The spectrum of disease-causing mutations and the associated clinical features of these gene defects are unknown. METHODS: DNA sequences encoding cardiac myosin-binding protein C were determined in unrelated patients with familial hypertrophic cardiomyopathy. Mutations were found in 16 probands, who had 574 family members at risk of inheriting these defects. The genotypes of these family members were determined, and the clinical status of 212 family members with mutations in the gene for cardiac myosin-binding protein C was assessed. RESULTS: Twelve novel mutations were identified in probands from 16 families. Four were missense mutations; eight defects (insertions, deletions, and splice mutations) were predicted to truncate cardiac myosin-binding protein C. The clinical expression of either missense or truncation mutations was similar to that observed for other genetic causes of hypertrophic cardiomyopathy, but the age at onset of the disease differed markedly. Only 58 percent of adults under the age of 50 years who had a mutation in the cardiac myosin-binding protein C gene (68 of 117 patients) had cardiac hypertrophy; disease penetrance remained incomplete through the age of 60 years. Survival was generally better than that observed among patients with hypertrophic cardiomyopathy caused by other mutations in the genes for sarcomere proteins. Most deaths due to cardiac causes in these families occurred suddenly. CONCLUSIONS: The clinical expression of mutations in the gene for cardiac myosin-binding protein C is often delayed until middle age or old age. Delayed expression of cardiac hypertrophy and a favorable clinical course may hinder recognition of the heritable nature of mutations in the cardiac myosin-binding protein C gene. Clinical screening in adult life may be warranted for members of families characterized by hypertrophic cardiomyopathy.     

Inheritance of intrahepatic cholestasis of pregnancy in one kindred

We report three sisters with intrahepatic cholestasis of pregnancy (ICP) and the pedigree of the family, including six generations. ICP was observed in five successive generations; most of the patients also had cholelithiasis. The uniform expression, the complete penetrance of the trait and the direct parent-to-child transmission support the Mendelian dominant mode of inheritance. Determination of HLA A, B and C haplotype was made in five ICP patients, without any findings of HLA type common to everyone. X-linked inheritance cannot be excluded in this study.     

Prolonged intrahepatic cholestasis in acute-onset, severe autoimmune hepatitis

A 72-year-old woman was admitted because of jaundice and hepatocellular dysfunction. She was diagnosed with autoimmune hepatitis from laboratory test results showing high titers of antinuclear antibodies and negativity for hepatitis viral markers. Steroid i.v. pulse therapy and oral administration of prednisolone were effective in improving the liver function test results, except for hyperbilirubinemia. Elevated serum bilirubin levels, of approximately 20 mg/dl persisted for more than 6 months, despite the administration of ursodeoxycholic acid. Insulin-glucagon therapy was given for normalization of transaminases and then withdrawn 3 weeks after admission, but it was resumed at 3 months, resulting in a dramatic decrease in serum bilirubin levels, which then normalized in 2.5 months. Liver biopsy 6 months after onset showed chronic active hepatitis with bile plugs. Insulin-glucagon therapy, because of its choleretic effect, may be worth continuing even after recovery of acute hepatic failure.     

Diagnosis and therapy of blood coagulation disorders in intrahepatic cholestasis

The reduction of prothrombin level below 5% in a patient with intrahepatic cholestasis of pregnancy is reported. The necessity of controlling the Quick level or better factors II, VII, IX and X is discussed. A well-timed Vitamin K therapy in all cases with impaired secretion of bile during pregnancy is recommended.     

The changes of lipid metabolism and hemorrheology in intrahepatic cholestasis during pregnancy

OBJECTIVE: To identify the influence of the increased level of serum cholyglycine (CG) on lipid metabolism and hemorrheology in patients with intrahepatic cholestasis during pregnancy (ICP). METHODS: The concentrations of serum CG, total cholesterol (CH), triglycerides (TG), high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C), high shear and low shear of blood specific viscosity (HS and LS), plasma specific viscosity (PV) and hematocrit (HCT) were measured in 68 cases of primiparas with single pregnancy and 30 healthy nonpregnant women respectively. The group of ICP was composed of 35 cases with CG > 6 mumol/L, the group of normal pregnancy, 33 cases with CG < 6 mumol/L. RESULTS: The means of CG and the lipidic parameters in the two pregnant groups were significantly higher than those in the non-pregnancy group (P < 0.02-0.001) except the means of HDL-C between the groups of ICP and non-pregnancy. The levels of LDL-C, LDL-C/HDL-C, LS, PV and HCT in the ICP were significantly higher than those in the normal pregnancy group (P < 0.02-0.001). CONCLUSIONS: There are significant changes of lipid metabolism and hemorrheology in patients with ICP. However, these changes could be corrected after pregnancy termination, when the level of serum CG returned to normal. The results suggest that the pathophysiologic changes of ICP are associated with increased level of serum CG.     

Small bile duct abnormalities and chronic intrahepatic cholestasis in Beh?et's syndrome

A 42-year-old man with Beh?et's disease of the intestinal type and a chronic cholestatic profile is presented. He had oral aphthea, genital ulcer, erythema nodosum, thrombophlebitis and central retinitis during the clinical course. Deep ileal ulcers recurred with massive bleeding and perforation. Cholestatic laboratory findings were also noted in the clinical course. A biopsied liver specimen, taken at the second operation for the ileal ulcer, showed chronic portal inflammation associated with ductopenia and epithelial degeneration of the small interlobular bile ducts, but periductal concentric fibrosis was not found. The patient died of sepsis 7 months after the last laparotomy. Although there was no significant abnormality in the large biliary tract at autopsy, pericholangitis in the small portal tracts and cholestasis were pronounced. Sclerosing cholangitis is one of well-known complications of ulcerative colitis or Crohn's disease. We report herein another rare association of small bile duct damage resembling sclerosing cholangitis with enteritis in Beh?et's disease.     

Mutations in a novel cochlear gene cause DFNA9, a human nonsyndromic deafness with vestibular dysfunction

The effect of systemic administration of the selective neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) on noradrenaline efflux in the frontal cortex was studied in freely-moving rats using microdialysis in vivo. Five days after treatment with DSP-4 (40 mg/kg i.p.), the noradrenaline content of the frontal cortex was reduced by 75%. Yet, noradrenaline efflux in the frontal cortex was nearly two-fold greater in DSP-4 treated rats than in saline-injected controls. Local infusion of the noradrenaline-selective uptake blocker, desipramine (5 microM), via the microdialysis probe, increased noradrenaline efflux in rats from both groups. Perfusion of Ringer's solution, containing 80 mM K+, also increased noradrenaline efflux in both groups, but the increase after DSP-4 pretreatment was greater than in the controls. In contrast, removal of Ca2+ from the infusion medium reduced noradrenaline efflux in both treatment groups. These results indicate that, at this dose, DSP-4 increases the extracellular concentration of noradrenaline in rat frontal cortex despite causing a partial lesion of noradrenergic neurones. This is due to an increase in the release of noradrenaline, although reduced clearance is also likely. These data challenge the assumption that depletion of noradrenaline content after treatment with DSP-4 invariably translates into diminished noradrenergic transmission.     

Pulmonary yellow hyaline membrane disease. New variant in premature infants with intrahepatic cholestasis

Two premature female infants with a new variant of pulmonary hyaline membrane disease had both received assisted ventilation with high oxygen concentrations. Postmortem examination showed straw-yellow hyaline membranes lining the terminal bronchioles and alveoli. Pneumonocytes and macrophages also contained straw-yellow pigments in the cytoplasm. These yellow membranes and pigments in pneumonocytes and in macrophages stained positively for bile and negatively for iron. Both infants had severe intrahepatic cholestasis. Cholestasis and pulmonary changes due to oxygen toxicity are believed to be the main features leading to this curious entity.     

Mutations in mouse Aristaless-like4 cause Strong's luxoid polydactyly

Mutations that affect vertebrate limb development provide insight into pattern formation, evolutionary biology and human birth defects. Patterning of the limb axes depends on several interacting signaling centers; one of these, the zone of polarizing activity (ZPA), comprises a group of mesenchymal cells along the posterior aspect of the limb bud that express sonic hedgehog (Shh) and plays a key role in patterning the anterior-posterior (AP) axis. The mechanisms by which the ZPA and Shh expression are confined to the posterior aspect of the limb bud mesenchyme are not well understood. The polydactylous mouse mutant Strong's luxoid (lst) exhibits an ectopic anterior ZPA and expression of Shh that results in the formation of extra anterior digits. Here we describe a new chlorambucil-induced deletion allele, lstAlb, that uncovers the lst locus. Integration of the lst genetic and physical maps suggested the mouse Aristaless-like4 (Alx4) gene, which encodes a paired-type homeodomain protein that plays a role in limb patterning, as a strong molecular candidate for the Strong's luxoid gene. In genetic crosses, the three lst mutant alleles fail to complement an Alx4 gene-targeted allele. Molecular and biochemical characterization of the three lst alleles reveal mutations of the Alx4 gene that result in loss of function. Alx4 haploinsufficiency and the importance of strain-specific modifiers leading to polydactyly are indicative of a critical threshold requirement for Alx4 in a genetic program operating to restrict polarizing activity and Shh expression in the anterior mesenchyme of the limb bud, and suggest that mutations in Alx4 may also underlie human polydactyly.     

Are altered pHi and membrane potential in hu MDR 1 transfectants sufficient to cause MDR protein-mediated multidrug resistance?

Multidrug resistance (MDR) mediated by overexpression of the MDR protein (P-glycoprotein) has been associated with intracellular alkalinization, membrane depolarization, and other cellular alterations. However, virtually all MDR cell lines studied in detail have been created via protocols that involve growth on chemotherapeutic drugs, which can alter cells in many ways. Thus it is not clear which phenotypic alterations are explicitly due to MDR protein overexpression alone. To more precisely define the MDR phenotype mediated by hu MDR 1 protein, we co-transfected hu MDR 1 cDNA and a neomycin resistance marker into LR73 Chinese hamster ovary fibroblasts and selected stable G418 (geneticin) resistant transfectants. Several clones expressing different levels of hu MDR 1 protein were isolated. Unlike previous work with hu MDR 1 transfectants, the clones were not further selected with, or maintained on, chemotherapeutic drugs. These clones were analyzed for chemotherapeutic drug resistance, intracellular pH (pHi), membrane electrical potential (Vm), and stability of MDR 1 protein overexpression. LR73/hu MDR 1 clones exhibit elevated pHi and are depolarized, consistent with previous work with LR73/mu MDR 1 transfectants (Luz, J.G. L.Y. Wei, S. Basu, and P.D. Roepe. 1994. Biochemistry. 33:7239-7249). The extent of these perturbations is related to the level of hu MDR 1 protein that is expressed. Cytotoxicity experiments with untransfected LR73 cells with elevated pHi due to manipulating percent CO2 show that the pHi perturbations in the MDR 1 clones can account for much of the measured drug resistance. Membrane depolarization in the absence of MDR protein expression is also found to confer mild drug resistance, and we find that the pHi and Vm changes can conceivably account for the altered drug accumulation measured for representative clones. These data indicate that the MDR phenotype unequivocally mediated by MDR 1 protein overexpression alone can be fully explained by the perturbations in Vm and pHi that accompany this overexpression. In addition, MDR mediated by MDR protein overexpression alone differs significantly from that observed for MDR cell lines expressing similar levels of MDR protein but also exposed to chemotherapeutic drugs.     

Mutations in pncA, a gene encoding pyrazinamidase/nicotinamidase, cause resistance to the antituberculous drug pyrazinamide in tubercle bacillus

Naturally pyrazinamide (PZA)-resistant Mycobacterium bovis and acquired PZA-resistant M. tuberculosis strains lose pyrazinamidase (PZase). To investigate the molecular mechanism of PZA resistance, we have cloned the gene (pncA) encoding M. tuberculosis PZase. Mutations in pncA were identified in both types of PZA-resistant strains, and transformation of these strains with a functional pncA gene restored PZase activity and PZA susceptibility. These findings, besides providing the basis for understanding how PZA works, should have implications for rapid detection of PZA-resistant clinical isolates of M. tuberculosis and also for rapid differentiation of M. bovis from M. tuberculosis strains.     

Mutations can cause large changes in the conformation of a denatured protein

Deletion of 13 amino acids from the carboxyl terminus of staphylococcal nuclease (WTSNase delta) results in a denatured, partially unfolded molecule that lacks significant persistent secondary structure but is relatively compact and monomeric under physiological conditions [Shortle & Meeker (1989) Biochemistry 28, 936-944; Flanagan et al. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 748-752]. Because of these and other properties of the SNase delta polypeptide, it is a useful model system for investigating the conformation of the denatured state of a protein without using extreme temperature or solvent conditions. Moreover, since the modification is a carboxyl-terminal deletion, SNase delta may also resemble a transient state of the polypeptide chain as it emerges from a ribosome prior to its folding. In the present study, we have examined the sizes and conformations of mutated forms of SNase delta, using small-angle X-ray scattering and circular dichroism spectroscopy. Seven mutated forms were studied: four with single substitutions, two with double substitutions, and one triple substitution. When present in the full-length SNase, each of these mutated forms exhibited unusual behavior upon solvent or thermal denaturation. In the case of the truncated form (SNase delta), the small-angle scattering curves of the mutated forms fall into two classes: one resembling the scattering curve of compact native nuclease and the other having features consistent with those expected for an expanded coil-like polymer. In contrast, the scattering curve of WT SNase delta exhibits features intermediate between those observed for globular proteins and random polymers. The amino acid substitutions that gave rise to compact, native-like versions of SNase delta were all of the m--type (m-substitutions are predicted to decrease the size of the denatured state). Those which gave rise to versions of SNase delta that were more extended and coil-like than WT SNase delta were of the m+ type (m+ substitutions are predicted to increase the size of the denatured state). Estimates of the residual secondary structure present in WT SNase delta, as well as both the m+ and m-substituted versions of SNase delta, as determined by CD, suggest that the formation of secondary structure and compaction of the polypeptide chain occur concurrently. Our results show that single amino acid substitutions can radically alter the conformational distribution of a partially condensed polypeptide chain.(ABSTRACT TRUNCATED AT 400 WORDS)     

Mirizzi''s syndrome as the cause of intrahepatic lithiasis. A clinical case

The authors report a case of Mirizzi's syndrome that was the cause of intrahepatic lithiasis. The recurrence of acute episodes of cholecystitis may lead to a partial obstruction of hepato-choledochal duct through compression and phlogosis (Type 1 Mirizzi's syndrome); moreover, the compression of calculous material wedged in the cystic duct may also result in ischemic necrosis of the wall, thus causing a cholecystic-choledochal internal biliary fistula (Type 2 Mirizzi's syndrome). The authors analyse problems relating to the complications of gallbladder calculosis with indications for surgery at the first symptomatic manifestation, given that the recurrence of cholecystic inflammatory episodes provokes pathological conditions in the biliary tract that require major surgery with a consequent increase in mortality and morbidity, above all in elderly patients. The authors recommended performing a through intraoperative study to ensure the correct identification of intrahepatic lithiasis, given the difficulty of preoperative diagnosis. The objective of treatment is to suppress the lithogenic focus and ensure good biliary drainage.