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Molecular genetic and immunohistochemical study of autosomal recessive Alport's syndrome.

A DNA analysis of autosomal type IV collagen alpha3 and alpha4 chain genes (COL4A3 and COL4A4) and an immunohistochemical study of type IV collagen alpha1 to alpha6 chains were performed in an inbred family with autosomal recessive Alport's syndrome (AS). A linkage study using polymorphic markers around the COL4A3/COL4A4 genes clearly differentiated the affected patients from healthy individuals. These patients were homozygous for all markers analyzed, whereas their parents were heterozygotes. Because of the large size of both the genes and the heterogeneous range of the mutations of these genes, linkage analysis by using highly polymorphic markers is still the method of choice in genetic counseling for autosomal recessive AS, as well as for the X-linked form. Although the distribution of alpha1 and alpha2 chains in the index patient and her affected sister were normal, the alpha3 and alpha4 chains were completely defective in the renal basement membrane (BM). The alpha5 chain could be found in Bowman's capsular basement membrane (BCBM) but not in the glomerular basement membrane (GBM). In addition, our study showed, for the first time, that the alpha6 chain in BCBM is spared in this form of AS. This abnormal pattern of type IV collagen could be a useful tool for differentiation of the autosomal recessive type from the X-linked type of AS.

Adolescent↗

Endoscopic gastrocnemius recession: preliminary report on 18 cases.

A technique of endoscopic gastrocnemius recession was evaluated. Fifteen patients undergoing 18 procedures were prospectively studied with a minimum follow-up of 1 year. There were 9 women and 6 men (mean age, 44.1 +/- 22.6 years). One patient had an isolated recession; the others had various adjunctive flatfoot or reconstructive procedures. Pre- and postoperative ankle dorsiflexion was evaluated, as was the amount of time before patients could perform a single-leg heel raise postoperatively. The mean preoperative ankle dorsiflexion with the knee extended was -8.7 degrees +/- 3.5 degrees , which improved from a mean 14.9 degrees at 3 months postoperatively to a mean 6.2 degrees +/- 2.6 degrees . At 12 months postoperatively, this value was 3.6 degrees +/- 1.8 degrees , a net postoperative improvement of 12.6 degrees (P < .00001). Patients were able to perform a single-leg heel raise on an average of 13.0 +/- 6.0 weeks. Complications were mostly related to lateral foot dysesthesia in the distribution of the sural nerve (N = 3). Furrowing of the medial leg was noted in 1 patient. No hematomas or neuromas associated with the portal sites were found. These results show endoscopic gastrocnemius recession to be an acceptable method of lengthening the gastrocnemius complex.

Adolescent↗

[Effectiveness of oblique recession with and without resection of horizontal recti in A and V patterns (author's transl)].

Report on 50 patients (17 V-esotropia, 6 V-exotropia, 17 A-esotropia, 10 A-exotropia) who were re-examined between six weeks and six months after oblique recession without/with resection of horizontal recti (procedure of Bietti, Boyd, Lavat et al.). The reduction in A and V patterns achieved varied considerably and nd was unpredictable. In 45% of the patients there was no change at all, or at most a slight change of less than 3%. Thus, the procedure appears to be less effective than oblique muscle surgery or vertical transposition of horizontal recti. Nevertheless, the oblique recession-resection procedure might be of limited use of torsional effects induced by transposition of horizontal recti are undesirable for functional reasons. A curious finding was the reduction in A and V patterns in three out of five patients who were treated with oblique recessions without/with resection in the opposite direction.

Esotropia↗

Lack of efficacy of phenytoin in recessive dystrophic epidermolysis bullosa. Epidermolysis Bullosa Study Group.

BACKGROUND: Recessive dystrophic epidermolysis bullosa is an uncommon, severely disabling, heritable disorder characterized by abnormal fragility of the skin. Open trials have suggested that phenytoin is an effective treatment, and this therapy is now widely used. METHODS: To determine the efficacy of phenytoin in the treatment of recessive dystrophic epidermolysis bullosa, we performed a randomized, double-blind, placebo-controlled, crossover trial in 36 patients. Each treatment was given for five to seven months, separated by a two-month period. We measured the total number of blisters and erosions on the entire body, the size of three plaques containing blisters and erosions, and the number of blisters and erosions in the three plaques at the beginning and end of each treatment period in each patient. RESULTS: Twenty-two patients completed both courses of therapy, seven patients completed one course, and seven patients withdrew before completing a single course. There was no significant difference in disease activity between phenytoin treatment and placebo treatment, as measured by changes in the number of blisters and erosions on the entire body (7 percent decrease vs. 6 percent increase), in the area of three designated plaques (0.4 percent decrease vs. 0.2 percent increase), or in the number of blisters and erosions in the designated plaques (12 percent decrease vs. 31 percent increase). CONCLUSIONS: Phenytoin is not an effective treatment for patients with recessive dystrophic epidermolysis bullosa.

Adolescent↗

Recessive-interfering mutations in the gibberellin signaling gene SLEEPY1 are rescued by overexpression of its homologue, SNEEZY.

This article reports the genetic interaction of two F-box genes, SLEEPY1 (SLY1) and SNEEZY (SNE), in Arabidopsis thaliana gibberellin (GA) signaling. The SLY1 gene encodes an F-box subunit of a Skp1-cullin-F-box (SCF) E3 ubiquitin ligase complex that positively regulates GA signaling. The sly1-2 and sly1-10 mutants have recessive, GA-insensitive phenotypes including delayed germination, dwarfism, reduced fertility, and overaccumulation of the DELLA proteins RGA (Repressor of ga1-3), GAI (GA-Insensitive), and RGL2 (RGA-Like 2). The DELLA domain proteins are putative transcription factors that negatively regulate GA signaling. The requirement for SLY1 in GA-stimulated disappearance of DELLA proteins suggests that GA targets DELLA proteins for destruction via SCF(SLY1)-mediated ubiquitylation. Overexpression of SLY1 in sly1-2 and sly1-10 plants rescues the recessive GA-insensitive phenotype of these mutants. Surprisingly, antisense expression of SLY1 also suppresses these mutants. This result caused us to hypothesize that the SLY1 homologue SNE can functionally replace SLY1 in the absence of the recessive interfering sly1-2 or sly1-10 genes. This hypothesis was supported because overexpression of SNE in sly1-10 rescues the dwarf phenotype. In addition to rescuing the sly1-10 dwarf phenotype, SNE overexpression also restored normal RGA protein levels, suggesting that the SNE F-box protein can replace SLY1 in the GA-induced proteolysis of RGA. If the C-terminal truncation in the sly1-2 and sly1-10 alleles interferes with SNE rescue, we reasoned that overexpression of sly1-2 might interfere with wild-type SLY1 function. Indeed, overexpression of sly1-2 in wild-type Ler (Landsberg erecta) yields dwarf plants.

Alkyl and Aryl Transferases↗

Effectiveness of retroequatorial recession surgery in congenital nystagmus.

OBJECTIVE: The aim of this retrospective study was to evaluate the effectiveness of the retroequatorial recession technique in the surgical treatment of nystagmus and associated strabismus. METHOD: The effect of large recessions of four horizontal extraocular muscles was analyzed qualitatively in seven patients with congenital nystagmus. RESULTS: The ages of the patients ranged between 12 and 42 years (mean, 21.5 years). Of the seven patients, four had motor and three had sensory nystagmus. Visual acuity increased in five (71.4%) patients. Planned recovery of associated strabismus was attained in six patients (85.7%). In five patients who had abnormal head position, the head positions and nystagmus intensities were found to be decreased. No postoperative complication, such as diplopia, was encountered. CONCLUSION: The retroequatorial recession technique is preferable in patients who have congenital nystagmus, especially in the presence of horizontal squint associated with low visual acuity, because of its success in increasing visual acuity and decreasing the amplitude of nystagmus, its reversibility, making posssible new operations in the future, as well as the absence of any significant complications.

Adolescent↗

Effects of recessive white plumage colour mutation on hatchability and growth of quail hatched from breeders of different ages.

1. A total of 1200 eggs were obtained from two pure line stocks of 'wild' and 'recessive white' quail of the Pharaoh strain (Coturnix coturnix Pharaoh), with two different breeder ages (17 or 34 weeks). The recessive white line was derived from mutant birds, which appeared spontaneously within the wild-type quail colony. 2. The analysis included plumage colour and breeder age as main effects together with their interaction. There were no significant effects for apparent fertility but hatchability of total and fertile eggs was affected by plumage colour variant and breeder age. 3. Body weight was affected by plumage colour throughout the growing period, whereas the differences attributable to breeder age were significant from 21 to 42 d only. 4. Main effects and their interaction were significant for feed conversion ratio until the end of the growing period, except at the age of 7 d for the effect of breeder age. 5. It was concluded that the hatchability and growth performance of the recessive white-type was not as good as the wild-type. The young breeders (17 weeks old) had the best hatchability and subsequent growth performance.

Aging↗

Novel mutations in the connexin 26 gene (GJB2) that cause autosomal recessive (DFNB1) hearing loss.

Mutations in the connexin 26 (Cx26) gene (GJB2) are associated with the type of autosomal recessive nonsyndromic neurosensory deafness known as "DFNB1." Studies indicate that DFNB1 (13q11-12) causes 20% of all childhood deafness and may have a carrier rate as high as 2. 8%. This study describes the analysis of 58 multiplex families each having at least two affected children diagnosed with autosomal recessive nonsyndromic deafness. Twenty of the 58 families were observed to have mutations in both alleles of Cx26. Thirty-three of 116 chromosomes contained a 30delG allele, for a frequency of .284. This mutation was observed in 2 of 192 control chromosomes, for an estimated gene frequency of .01+/-.007. The homozygous frequency of the 30delG allele is then estimated at .0001, or 1/10,000. Given that the frequency of all childhood hearing impairment is 1/1,000 and that half of that is genetic, the specific mutation 30delG is responsible for 10% of all childhood hearing loss and for 20% of all childhood hereditary hearing loss. Six novel mutations were also observed in the affected population. The deletions detected cause frameshifts that would severely disrupt the protein structure. Three novel missense mutations, Val84Met, Val95Met, and Ser113Pro, were observed. The missense mutation 101T-->C has been reported to be a dominant allele of DFNA3, a dominant nonsyndromic hearing loss. Data further supporting the finding that this mutation does not cause dominant hearing loss are presented. This allele was found in a recessive family segregating independently from the hearing-loss phenotype and in 3 of 192 control chromosomes. These results indicate that 101T-->C is not sufficient to cause hearing loss.

Alleles↗

Inactivate the remaining p53 allele or the alternate p73? Preferential selection of the Arg72 polymorphism in cancers with recessive p53 mutants but not transdominant mutants.

Several reports have noted epidemiological differences in the prevalence or prognostic significance of p53 mutants with arginine (R) or proline (P) at the codon 72 polymorphism (R72/P72) in certain cancer types, but the biological significance of these variants is unclear. The ability of p53 mutants to interact with and inactivate the p53 homolog p73 was recently reported to depend on the conformational state of the p53 protein and the residue at codon 72. Since the conformation of p53 mutants may influence their ability to transdominantly inhibit wild-type p53, we tested whether there was a correlation between the amino acid at codon 72 and the transdominance of p53 alleles found in tumors. The transdominance test was performed using a simple yeast transcription assay, and the amino acid at codon 72 was determined by sequencing. A total of 100 p53 mutants were tested. Compared with the germline frequency (R:P = 427:297), an extreme bias in favor of the R72 allele was observed with recessive mutants (R:P = 50:7, P < 0.0002), whereas no selection for the R72 allele was seen with transdominant mutants (R:P = 23:20). p53 and p73 are known to transactivate overlapping sets of target genes. We interpret the R72 bias with recessive mutants as evidence that decreased activation of p53 target genes provides a selective growth advantage to tumor cells during the stage of tumorigenesis in which a wild-type and mutant p53 allele coexist. We suggest that transdominant p53 mutants achieve this by inactivation of the remaining wild-type p53 allele, whereas recessive p53 mutants achieve it through inactivation of p73.

Alleles↗

A gene for a dominant form of non-syndromic sensorineural deafness (DFNA11) maps within the region containing the DFNB2 recessive deafness gene.

Hereditary hearing loss is divided into two groups, syndromic and non-syndromic, the latter being more common and highly heterogeneous. Linkage analyses were performed on a Japanese family showing a dominant form of non-syndromic progressive sensorineural hearing loss. This gene (DFNA11) was localized within the region of chromosome 11q which contains the second gene for a recessive form of non-syndromic sensorineural hearing loss (DFNB2). Since it has been reported that another gene for dominant non-syndromic hearing loss (DFNA3) has been mapped to the same region as the first gene for recessive hearing loss (DFNB1), it is possible that different mutations in the DFNB2 gene may result in either dominant or recessive hearing loss.

Adolescent↗

Two different connexin 26 mutations in an inbred kindred segregating non-syndromic recessive deafness: implications for genetic studies in isolated populations.

Non-syndromic recessive deafness (NSRD) is the most common form of prelingual hereditary hearing loss. To date, 10 autosomal NSRD loci (DFNBs) have been identified by genetic mapping; at least three times as many additional loci are expected to be identified. We have performed linkage analyses in two inter-related inbred kindreds, comprised of >50 affecteds, from a single Israeli-Arab village segregating NSRD. Genetic mapping by two-point and multi-point linkage analysis in 10 candidate regions identified the segregating gene to be on human chromosome 13q11 (DFNB1). Haplotype analysis, using eight microsatellite markers spanning 15 cM in 13q11, suggested the segregation of two different mutations in this kindred: affected individuals were homozygotes for either haplotype or compound heterozygotes. The gene for the connexin 26 gap junction protein, recently shown to be mutant in both dominant and recessive deafness, maps to this locus. We identified two distinct mutations, W77R and Gdel35, both of which likely inactivate connexin 26. The Gdel35 change likely occurs at a mutational hotspot within the connexin 26 gene. The recombination of marker alleles at the polymorphisms studied in 13q11, at known map distances from the mutations, allowed us to estimate the age of the mutations to be 3-5 generations (75-125 years). This study independently confirms the identity of connexin 26 as an NSRD gene. Importantly, we demonstrate that in small populations with high rates of consanguinity, as compared with large outbred populations, recessive mutations may have very recent origin and show allelic diversity.

Chromosomes, Human, Pair 13↗

Characterization of the peripheral retinopathy in X-linked and autosomal recessive Alport syndrome.

BACKGROUND: Alport syndrome is an inherited disease resulting in kidney failure, hearing loss and ocular abnormalities. Alport syndrome is however often unrecognized, and the aim of this study was to characterize the associated but rarely described peripheral retinopathy and determine whether its demonstration was diagnostically helpful. METHODS: Index cases were diagnosed with Alport syndrome on renal biopsy in themselves or a family member. Inheritance and affected status were determined using microsatellite markers at the COL4A5 and COL4A3/COL4A4 loci, respectively. Participants' eyes were dilated, and examined with direct and indirect ophthalmoscopy, and slit lamp biomicroscopy by an expert ophthalmologist who was unaware of the patients' disease status. RESULTS: Ten males and nine females with X-linked Alport syndrome and seven with autosomal recessive disease were studied. Of the 26 patients, 16 had central retinopathy (62%), and 19 patients had peripheral retinopathy (74%). The peripheral changes occurred in both males and females with X-linked and autosomal recessive Alport syndrome, and were more common when renal failure, hearing loss, lenticonus and the central changes were present, but were also noted in 3 X-linked carriers with normal renal function. CONCLUSIONS: The peripheral retinopathy occurs in X-linked and autosomal recessive Alport syndrome even when the central retinopathy is absent. Careful retinal examination and photography that includes the periphery is a safe and inexpensive method that may help in the diagnosis of Alport syndrome especially in carriers of X-linked disease.

Adolescent↗

Pericardial "sleeve" recess of right inferior pulmonary vein mimicking adenopathy: computed tomography findings.

OBJECTIVE: The purpose of this study was to assess the computed tomography (CT) features of the pericardial "sleeve" recess of the right inferior pulmonary vein misinterpreted as adenopathy. METHOD: Six patients with fluid in the pericardial sleeve recess mistaken for adenopathy were retrospectively identified. The following CT features were assessed: location of fluid in relation to the vein, size, shape, attenuation, and mass effect on the inferior pulmonary vein. RESULTS: The most common presentation was fluid inferior and posterior to the vein. The anterior and posterior components are typically spindle shaped, whereas the superior and inferior components are ovoid. The attenuation values of the fluid ranged from 2-32 H (mean = 13 H). None of the fluid collections exerted mass effect on the right inferior pulmonary vein. CONCLUSION: Although fluid in the right pulmonary venous sleeve pericardial recess can mimic adenopathy, this accumulation has a characteristic appearance, and knowledge of this normal variant is useful in preventing misinterpretation.

Aged↗

Advances in the molecular genetics of the limb-girdle type of autosomal recessive progressive muscular dystrophy.

A reclassification of the limb-girdle types of autosomal recessive muscular dystrophy based on genetic and protein information has been made possible by major advances over the past 2 years. At least six different forms of limb-girdle types of autosomal recessive muscular dystrophy can be defined by their genetic basis, with at least two pathogenic mechanisms involved. Three forms are defined by involvement of different proteins of the sarcoglycan complex, while a muscle specific protease (calpain 3) is implicated in another form of the recessive disease. These findings provide the basis for a new diagnostic approach to the group, with molecular techniques now an essential part of the diagnostic process. A scheme for diagnosis in this group is proposed.

Cytoskeletal Proteins↗

Transfacial recess ossicular reconstruction: technique and early results.

OBJECTIVES: The objective of this study was to present the technique of transfacial recess ossicular chain reconstruction (TFROCR) for potential use in selected patients with cholesteatoma. STUDY DESIGN: The author conducted a retrospective case review of all candidates for TFROCR between August 1998 and March 2003. SETTING: A tertiary referral center. PATIENTS: At first-stage tympanomastoidectomy, 22 ears (21 patients; 8 children and 13 adults) with cholesteatoma and ossicular discontinuity were identified as candidates for TFROCR. Seven patients had undergone previous tympanomastoid surgery. INTERVENTION: The first stage included canal wall up mastoidectomy with resection of disease, wide opening of the facial recess, cartilage graft tympanoplasty, and placement of silicone elastomer in the middle ear. Approximately 6 months later, patients underwent a second-stage postauricular procedure. Endoscopes were used to inspect the middle ear through the facial recess. When possible, TFROCR was then performed without elevating a tympanomeatal flap. MAIN OUTCOME MEASURES: Variations in anatomy, disease control, and hearing results were studied. RESULTS: Of the 22 candidate ears, 17 successfully underwent TFROCR, whereas 5 required traditional second-stage procedures with canal incisions. There were no surgical complications. Early hearing results are promising with an average air-bone gap of less than 20 dB. There have been no early failures from recurrent disease or prosthesis displacement. CONCLUSIONS: In carefully selected patients, TFROCR could be safe and effective for disease control and hearing restoration. It could provide for optimal prosthesis placement and almost immediate hearing improvement, avoiding the need for canal incisions, middle ear packing, and dry ear precautions. One must consider the potential risk of missing residual disease secondary to limited exposure.

Adolescent↗

Investigation of C-arm cone-beam CT-guided surgery of the frontal recess.

OBJECTIVE/HYPOTHESIS: A cone-beam CT (CBCT) imaging system based on a mobile C-arm (Siemens PowerMobil) incorporating a high-performance flat-panel detector (Varian PaxScan) has been developed in our laboratory. We hypothesize that intraoperative C-arm CBCT provides image quality and guidance performance sufficient to assist surgical approach to the frontal recess. STUDY DESIGN: A preclinical prospective study was conducted using six cadaver heads to assess the performance characteristics and the potential clinical utility of this imaging system. METHODS: The mobile C-arm was employed for intraoperative CBCT guidance of the endoscopic approach to twelve frontal recesses. RESULTS: The imaging system is capable of sub-mm 3D spatial resolution with bone and soft-tissue visibility and a field of view sufficient for guidance of head and neck surgery. The system can generate intraoperative, volumetric CT images rapidly with an acceptably low radiation exposure to the patient and with image quality sufficient for most surgical tasks. Moreover, the system is portable and compatible with the surgical setup, providing excellent access to the patient. Finally, the accuracy of the system is not bound to a registration process. CONCLUSIONS: The ability to create updated images as surgery progresses introduces the concept of 'near-real-time' CT guidance for head and neck surgery. We found that the use of CBCT increased surgical confidence in accessing the frontal recess, resolved ambiguities with anatomical variations, and provided valuable teaching information to surgeons in training in both preoperative planning and correlation between tri-planar CT scans and intraoperative endoscopic findings.

Cadaver↗

Two classes of deleterious recessive alleles in a natural population of zebrafish, Danio rerio.

Natural populations carry deleterious recessive alleles which cause inbreeding depression. We compared mortality and growth of inbred and outbred zebrafish, Danio rerio, between 6 and 48 days of age. Grandparents of the studied fish were caught in the wild. Inbred fish were generated by brother-sister mating. Mortality was 9% in outbred fish, and 42% in inbred fish, which implies at least 3.6 lethal equivalents of deleterious recessive alleles per zygote. There was no significant inbreeding depression in the growth, perhaps because the surviving inbred fish lived under less crowded conditions. In contrast to alleles that cause embryonic and early larval mortality in the same population, alleles responsible for late larval and early juvenile mortality did not result in any gross morphological abnormalities. Thus, deleterious recessive alleles that segregate in a wild zebrafish population belong to two sharply distinct classes: early-acting, morphologically overt, unconditional lethals; and later-acting, morphologically cryptic, and presumably milder alleles.

Alleles↗

Direct bonding of recessed-structure SAW filter on silicon substrate.

A procedure for fabricating a recessed surface acoustic wave (SAW) device coupled with silicon substrate is reported. The recessed structure is stable and rugged enough against the bonding process, and it can be applied to integrate a semiconductor device into one chip by a direct bonding technique. In this paper, the tensile strength of silicon (Si)-to-recessed-SAW filter is measured, and the performance of the device is discussed.

Letter↗