Clinical and genetic findings in a family with NMNAT1-associated Leber congenital amaurosis: case report and review of the literature.

BACKGROUND: Leber congenital amaurosis (LCA) is a severe retinal dystrophy, typically manifesting in the first year of life. Mutations in more than 18 genes have been reported to date. In recent studies, biallelic mutations in NMNAT1 encoding nicotinamide mononucleotide adenylyltransferase 1 have been found to cause LCA. PURPOSE: To broaden the knowledge regarding the phenotype of NMNAT1-associated LCA. METHODS: Clinical ophthalmologic examinations were performed in two sisters with LCA. Whole exome sequencing was performed in one of the affected girls, with subsequent segregation analysis in the affected sister and unaffected parents. The literature was reviewed for reports of NMNAT1-associated LCA. RESULTS: Exome sequencing revealed the known NMNAT1 mutation c.25G>A (p.Val9Met) in a homozygous state. Segregation analysis showed the same homozygous mutation in the affected younger sister. Both parents were found to be heterozygous carriers of the mutation. The two girls both presented with severe visual impairment, nystagmus, central atrophy of the pigment epithelium, and pigment clumping in the periphery before the age of 6 months. Retinal vessels were attenuated. Both children were hyperopic. In the older sister, differential diagnosis included an inflammatory origin, but electrophysiology in her as well as her sister confirmed a diagnosis of LCA. Pallor of the optic nerve head was not present at birth but developed progressively. CONCLUSIONS: We confirmed a diagnosis of NMNAT1-associated LCA in two siblings through identification of the mutation (c.25G>A [p. Val9Met]) in a homozygous state. In infants with non-detectable electroretinogram (ERG), along with severe congenital visual dysfunction or blindness and central pigment epithelium atrophy with pigment clumping resembling scarring due to chorioretinitis, LCA due to NMNAT1 mutations should be considered.

Mutation of CDH23, encoding a new member of the cadherin gene family, causes Usher syndrome type 1D.

Usher syndrome type I (USH1) is an autosomal recessive disorder characterized by congenital sensorineural hearing loss, vestibular dysfunction and visual impairment due to early onset retinitis pigmentosa (RP). So far, six loci (USH1A-USH1F) have been mapped, but only two USH1 genes have been identified: MYO7A for USH1B and the gene encoding harmonin for USH1C. We identified a Cuban pedigree linked to the locus for Usher syndrome type 1D (MIM 601067) within the q2 region of chromosome 10). Affected individuals present with congenital deafness and a highly variable degree of retinal degeneration. Using a positional candidate approach, we identified a new member of the cadherin gene superfamily, CDH23. It encodes a protein of 3,354 amino acids with a single transmembrane domain and 27 cadherin repeats. In the Cuban family, we detected two different mutations: a severe course of the retinal disease was observed in individuals homozygous for what is probably a truncating splice-site mutation (c.4488G-->C), whereas mild RP is present in individuals carrying the homozygous missense mutation R1746Q. A variable expression of the retinal phenotype was seen in patients with a combination of both mutations. In addition, we identified two mutations, Delta M1281 and IVS51+5G-->A, in a German USH1 patient. Our data show that different mutations in CDH23 result in USH1D with a variable retinal phenotype. In an accompanying paper, it is shown that mutations in the mouse ortholog cause disorganization of inner ear stereocilia and deafness in the waltzer mouse.

Mutations in CAV3 cause mechanical hyperirritability of skeletal muscle in rippling muscle disease.

Hereditary rippling muscle disease (RMD) is an autosomal dominant human disorder characterized by mechanically triggered contractions of skeletal muscle. Genome-wide linkage analysis has identified an RMD locus on chromosome 3p25. We found missense mutations in positional candidate CAV3 (encoding caveolin 3; ref. 5) in all five families analyzed. Mutations in CAV3 have also been described in limb-girdle muscular dystrophy type 1C (LGMD1C; refs. 6,7), demonstrating the allelism of dystrophic and non-dystrophic muscle diseases.

High frequency of autosomal-recessive DFNB59 hearing loss in an isolated Arab population in Israel.

Autosomal-recessive non-syndromic hearing impairment (DFNB) is usually of prelingual onset with a moderate to profound degree of hearing loss. More than 70 DFNB loci have been mapped and ~40 causative genes have been identified. Non-syndromic hearing impairment caused by mutations of DFNB59 (encoding pejvakin) has been described in a couple of families in which affected individuals presented with either auditory neuropathy or hearing loss of cochlear origin. We have identified and clinically evaluated three consanguineous families of Israeli Arab origin with prelingual non-syndromic hearing impairment and absent otoacoustic emissions in a total of eight affected individuals. All the families originate from the same village and bear the same family name. We have identified a c.406C>T (p.R136X) nonsense mutation in the DFNB59 gene in affected individuals from these families. Among the inhabitants of the village, we found an exceptionally high carrier frequency of ~1 in 12 individuals (7/85; 8.2%). The high prevalence of hearing impairment can be explained by a founder effect and the high consanguinity rate among the inhabitants of this village.

[Werner syndrome. A prototypical form of segmental progeria.] / Werner-Syndrom.

Werner syndrome is a segmental progeroid disorder with onset in adolescence or early adulthood. Typical symptoms contributing to patients' prematurely aged appearance include postpubertal development of short stature, cataracts, premature greying/thinning of scalp hair, scleroderma-like skin changes and regional atrophy of subcutaneous fat tissue. In addition, an increased rate and early onset of typical age-related diseases such as type 2 diabetes mellitus, osteoporosis, atherosclerosis, and various malignancies is observed. Werner syndrome is autosomal recessively inherited and caused by mutations in the Werner gene (WRN). To date, more than 70 WRN mutations have been identified. These are spread over the entire gene and typically represent loss of function mutations. WRN encodes a RecQ type helicase involved in DNA repair and the maintenance of DNA integrity, which is reflected by an increased genetic instability in patient cells. Despite the relative rarity of Werner syndrome, its analysis provides important general insights into the roles of DNA stability and integrity for the ageing process and the development of age-associated diseases.

Tauroursodeoxycholic acid reduces endoplasmic reticulum stress, trypsin activation, and acinar cell apoptosis while increasing secretion in rat pancreatic acini.

Endoplasmic reticulum (ER) stress leads to accumulation of un- or misfolded proteins inside the ER and initiates the unfolded protein response (UPR). Several UPR components are physiologically involved in pancreatic development and are pathophysiologically activated during acute pancreatitis. However, the exact role of ER stress in exocrine pancreatic acini is mainly unclear. The present study examined the effects of tauroursodeoxycholic acid (TUDCA), a known ER chaperone, on acinar function and UPR components. Isolated rat pancreatic acini were stimulated by increasing concentrations of cholecystokinin (CCK-8) with or without preincubation of TUDCA. UPR components were analyzed, including chaperone binding protein (BiP), protein kinase-like ER kinase (PERK), X-box binding protein (XBP)-1, c-Jun NH(2)-terminal kinase (JNK), CCAAT/enhancer binding protein homologues protein (CHOP), caspase 3 activation, and apoptosis. In addition, TUDCA effects were measured on amylase secretion, calcium signaling, trypsin, and cathepsin B activation. TUDCA preincubation led to a significant increase in amylase secretion after CCK-8 stimulation, a 50% reduction of intracellular trypsin activation, and reduced cathepsin B activity, although the effects for cathepsin B were not statistical significant. Furthermore, TUDCA prevented the CCK-8-induced BiP upregulation, diminished PERK and JNK phosphorylation, and prohibited the expression of CHOP, caspase 3 activation and apoptosis. XBP-1 splicing was not altered. ER stress response mechanisms are activated in pancreatic inflammation. Chemical chaperones enhance enzyme secretion of pancreatic acini, reduce ER stress responses, and attenuate ER stress-associated apoptosis. These data hint new perspectives for an employment of chemical chaperones in the therapy of acute pancreatitis.

A novel DFNB1 deletion allele supports the existence of a distant cis-regulatory region that controls GJB2 and GJB6 expression.

Eleven affected members of a large German-American family segregating recessively inherited, congenital, non-syndromic sensorineural hearing loss (SNHL) were found to be homozygous for the common 35delG mutation of GJB2, the gene encoding the gap junction protein Connexin 26. Surprisingly, four additional family members with bilateral profound SNHL carried only a single 35delG mutation. Previously, we demonstrated reduced expression of both GJB2 and GJB6 mRNA from the allele carried in trans with that bearing the 35delG mutation in these four persons. Using array comparative genome hybridization (array CGH), we have now identified on this allele a deletion of 131.4 kb whose proximal breakpoint lies more than 100 kb upstream of the transcriptional start sites of GJB2 and GJB6. This deletion, del(chr13:19,837,344-19,968,698), segregates as a completely penetrant DFNB1 allele in this family. It is not present in 528 persons with SNHL and monoallelic mutation of GJB2 or GJB6, and we have not identified any other candidate pathogenic copy number variation by arrayCGH in a subset of 10 such persons. Characterization of distant GJB2/GJB6 cis-regulatory regions evidenced by this allele may be required to find the 'missing' DFNB1 mutations that are believed to exist.

Oesophageal ulceration after selective internal radiation therapy in a patient with carcinoma of unknown primary.

BACKGROUND: Cancer of unknown primary (CUP) is defined as histologically confirmed metastases in the absence of an identifiable primary tumor. Patients with solely liver metastases from adenocarinomas represent the most frequent subgroup with an unfavourable prognosis. The medium survival averages 6 to 9 months. No chemotherapheutic standard has been established. CASE: We present a patient with hepatic CUP. After cycles of chemotherapy and hemihepatectomy the tumor returned and showed hepatic progression. The patient was evaluated for selective internal radiation therapy (SIRT). Three years after diagnosis she is still alive and tumorfree. Despite a good result and disease control our patient suffered radiation-induced ulceration in the oesophagus, stomach, and duodenum. This side effect appears in up to 12 % of patients, often very late after treatment, is refractory to pharmacotherapy and persistent over a long time. CONCLUSIONS: SIRT is a new, effective treatment in patients with hepatic CUP. Because of the anticipated increase of this therapy, adverse side effects such as ulcerations in the upper-GI tract secondary to ectopic implantation of microspheres may be seen more commonly. Awareness of this and the recognition of microspheres in biopsies is cardinal for appropriate management and maintenance of the patient's quality of life.

A potassium channel mutation in neonatal human epilepsy.

Benign familial neonatal convulsions (BFNC) is an autosomal dominant epilepsy of infancy, with loci mapped to human chromosomes 20q13.3 and 8q24. By positional cloning, a potassium channel gene (KCNQ2) located on 20q13.3 was isolated and found to be expressed in brain. Expression of KCNQ2 in frog (Xenopus laevis) oocytes led to potassium-selective currents that activated slowly with depolarization. In a large pedigree with BFNC, a five-base pair insertion would delete more than 300 amino acids from the KCNQ2 carboxyl terminus. Expression of the mutant channel did not yield measurable currents. Thus, impairment of potassium-dependent repolarization is likely to cause this age-specific epileptic syndrome.

Genetic association study of endothelin-1 and its receptors EDNRA and EDNRB in migraine with aura.

The effect of endothelin-1 and its receptors EDNRA and EDNRB in migraine with aura (MA) susceptibility is not established yet. We studied the association between the MA end-diagnosis and three migraine trait components and 32 single nucleotide polymorphisms (SNPs) capturing the variation of endothelin genes in 850 Finnish migraine patients and 890 non-migrainous individuals. The SNPs showing evidence of association were further studied in 648 German migraine patients and 651 non-migrainous individuals. No significant association was detected. However, the homozygous minor genotype (5% in cases) of the EDNRA SNP rs2048894 showed nominal association with MA both in the Finnish sample (P = 0.015) and in the pooled sample [odds ratio (OR) 1.61, 95% confidence interval (CI) 1.12-2.32, P = 0.010] when adjusted for gender and sample origin. The trait age of onset < 20 years was also associated with rs2048894 (OR 1.69, 95% CI 1.13-2.54, P = 0.011) in the pooled sample. To confirm this finding studies on even larger samples are required.

[Virtual endoscopy of the nose and paranasal sinuses in real-time. Surgical planning system "Sinus endoscopy" (SPS-SE)]. / Virtuelle Echtzeit-Endoskopie der Nase und Nasennebenhöhlen. Surgical-Planning-System "Sinus Endoscopy" (SPS-SE).

PROBLEM: The aim of this study was the development and clinical evaluation of a new method for virtual endoscopy of the nose and paranasal sinuses. MATERIAL AND METHODS: The surgical planning system "sinus endoscopy" (SPS-SE) was completely newly developed. The surfaces of the CT images are represented with direct volume rendering (raycasting) which allows a sufficiently high image repetition frequency with the movement of the virtual endoscopy and material effects for a natural appearance were added. Detail accuracy of the virtual illustrations was examined with the help of a picture-statistic comparison between optical and the virtual endoscopy. The evaluation of the system by the patients and physicians was made with a validated questionnaire. RESULTS: The deviations from defined landmarks of virtual in comparison to optical endoscopy are between 1.4 mm and 11.1 mm. Manoeuvering the virtual endoscope was found to be better than with the optical endoscope but the important parameters for visualization were similar. The accuracy of volume rendering, the high variability of scaling of the anatomical borders and orientation were judged to be negative factors. Altogether there was a balanced opinion from the ENT surgeons but without exception patients judged the system positively. DISCUSSION: This investigation proved the efficiency of SPS-SE for three-dimensional real time reconstruction of high-resolution CT data of the nose and paranasal sinuses. However, some modifications are necessary before introduction into routine use.

Complete genomic structure of the CLCN6 and CLCN7 putative chloride channel genes(1).

The CLC family of voltage-gated chloride channels comprises nine members in mammals. CLCN6 and CLCN7 belong to a novel, poorly characterized subbranch of this family. We investigated the genomic organization of the human CLCN6 gene, as well as the murine CLCN6 and CLCN7 genes. The human and murine CLCN6 genes both consist of 23 exons and share a nearly identical genomic structure. The coding region of mouse CLCN7 is composed of 25 exons. Comparison of the genomic organization of CLCN6 and CLCN7 genes shows that just eight introns are located at corresponding cDNA positions. Moreover, no significant gene structure homology to other members of the CLC family could be detected indicating a great structural diversity of mammalian CLC genes.

Characterization of ADAMTS14, a novel member of the ADAMTS metalloproteinase family.

ADAMTS (a disintegrin-like and metalloproteinase domain with thrombospondin type 1 modules) proteins constitute a family of zinc metalloproteinases which target and process extracellular matrix proteins. We cloned and characterized a novel human ADAMTS gene, ADAMTS14, which is located on human chromosome 10q2. ADAMTS14 exhibits the characteristic multidomain structure of ADAMTS proteins including four thrombospondin modules and shows highest similarity to ADAMTS3 and ADAMTS2. By RT-PCR analysis we demonstrated that ADAMTS14 is expressed in human retina and also at low levels in adult brain, lung and placenta.

Investigation of the Met-267 Arg exchange in isoform 1 of the human plasma membrane calcium pump in patients with essential hypertension by the amplification-created restriction site technique.

Alterations in Ca2+ homeostasis have been proposed to be a primary factor in the pathogenesis of essential hypertension. In this disease increased intracellular Ca2+ levels have repeatedly been reported in various cell types. Because of its prominent role in cellular calcium homeostasis in vascular smooth muscle cells, modifications of the plasma membrane Ca2+-ATPase (PMCA) pump have been suggested to contribute to an increased contractile tone of small blood vessels. This pump is a calmodulin-dependent Ca2+-ATPase that ejects Ca2+ from the cytosol into the extracellular space. Recently a mutational thymidine (T)-->guanosine (G) transversion in isoform 1 of the PMCA has been identified resulting in the substitution of a methionine (Met) by an arginine (Arg) at amino acid position 267 in a highly conserved domain of the pump molecule. The aim of our study was to determine the prevalence of this polymorphism in the normal population and to investigate whether the Met-267 Arg occurs more frequently in patients with essential hypertension than in normotensives. To detect the mutational change we modified a method based on the technique of amplification-created restriction sites (ACRS) using three base exchanges in the diagnostic primer. Samples from 100 hypertensive and 60 normotensive subjects revealed a thymidine at nucleotide position 981. These data suggest that ACRS is feasible in spite of extensive primer modifications (e.g., three mismatched bases) in contrast to the previously used one or two and may therefore be conceptually suitable to detect almost any base changes in the genome. The described T-->G transversion is a rare polymorphism and is presumably not related to common forms of essential hypertension.

Immediate-early gene induction by repetitive mechanical but not electrical activity in adult rat cardiomyocytes.

Mechanical factors are thought to play an important role in the induction of myocardial hypertrophy. Yet, it is not known whether active contraction induces genes that probably represent initial steps in the hypertrophic response in the adult myocardium--and if so, whether the mechanical or the electrical component of the twitch governs this response. We therefore investigated whether electrical stimulation of contraction was able to induce the immediate-early genes (IEGs) egr-1 and c-fos in adult rat cardiomyocytes. Cyclical contraction led to an increase in egr-1 and c-fos mRNA levels within 30 min. Full inhibition of contraction during electrostimulation by the Ca(2+)-desensitizer 2,3-butanedione monoxime (BDM) totally blocked this IEG-response without altering membrane potential. These data suggest that in adult myocardium, the mechanical rather than the electrical activity is responsible for the IEG-response during active twitch.

Phenotypic variability in rippling muscle disease.

OBJECTIVE: To characterize the phenotype of hereditary rippling muscle disease (RMD) and to report the results of genetic linkage studies. BACKGROUND: RMD is a rare autosomal-dominant inherited muscle disorder. Individuals complain of muscle stiffness, exercise-induced muscle pain, and cramp-like sensations. The characteristic feature of RMD is increased mechanical muscle irritability, which is electrically silent in electromyographic examinations. METHODS: Forty-six individuals from two unrelated German kindreds with RMD were examined. Linkage analysis to the RMD locus on chromosome 1q41-q43 was performed. RESULTS: In kindred A, 15 individuals from four generations, and in kindred B, four individuals from three generations had clinical features of RMD. The most consistent clinical findings were percussion-induced rapid muscle contractions (PIRCs) and muscle mounding, which were present in all 19 affected individuals. Only 12 individuals exhibited muscle rippling, indicating that rippling is not always present in RMD. Twelve of 19 individuals had muscle-related complaints, primarily exertional cramps and stiffness. The mean age at the onset of complaints was 22 years (range, 5 to 54 years). Seven of 19 individuals showed only mechanical-induced muscle irritability but did not have muscular symptoms. Genetic analysis excluded linkage to the RMD locus on chromosome 1q4 in both kindreds. CONCLUSIONS: The phenotype of RMD is variable but generalized PIRCs are the most obvious and reliable clinical feature of RMD. Diagnostic criteria of RMD should include generalized PIRCs in addition to muscle mounding, rippling, and creatine kinase elevation.

A sporadic case of rippling muscle disease caused by a de novo caveolin-3 mutation.

OBJECTIVE: To determine the cause of sporadic rippling muscle disease (RMD) in a 24-year-old patient. BACKGROUND: RMD is a rare myopathy characterized by percussion-induced rapid muscle contractions (PIRC), muscle mounding, and rippling waves. We have recently found that autosomal dominant RMD is caused by mutations in the caveolin-3 gene (CAV3) on chromosome 3p25. Possibly, increased activity of neuronal nitric oxide synthase (nNOS) contributes to the clinical characteristics of increased mechanical muscle hyperexcitability. METHODS: Clinical examination, mutational analysis, and immunohistochemistry of muscle tissue were performed in a patient with sporadic RMD. RESULTS: The authors observed a de novo CAV3 missense mutation Arg26Gln. Immunohistochemistry showed reduced caveolin-3 surface expression in a muscle biopsy. In addition, the authors found normal sarcolemmal nNOS expression and a reduced expression of alpha-dystroglycan in muscle fibers. CONCLUSIONS: These data confirm that RMD is caused by CAV3 mutations. Moreover, there is evidence that CAV3 mutations may also be found in patients without a positive family history of RMD.