Mutations in a novel gene with transmembrane domains underlie Usher syndrome type 3.

Usher syndrome type 3 (USH3) is an autosomal recessive disorder characterized by progressive hearing loss, severe retinal degeneration, and variably present vestibular dysfunction, assigned to 3q21-q25. Here, we report on the positional cloning of the USH3 gene. By haplotype and linkage-disequilibrium analyses in Finnish carriers of a putative founder mutation, the critical region was narrowed to 250 kb, of which we sequenced, assembled, and annotated 207 kb. Two novel genes-NOPAR and UCRP-and one previously identified gene-H963-were excluded as USH3, on the basis of mutational analysis. USH3, the candidate gene that we identified, encodes a 120-amino-acid protein. Fifty-two Finnish patients were homozygous for a termination mutation, Y100X; patients in two Finnish families were compound heterozygous for Y100X and for a missense mutation, M44K, whereas patients in an Italian family were homozygous for a 3-bp deletion leading to an amino acid deletion and substitution. USH3 has two predicted transmembrane domains, and it shows no homology to known genes. As revealed by northern blotting and reverse-transcriptase PCR, it is expressed in many tissues, including the retina.

Integration of FGF and TWIST in calvarial bone and suture development.

Mutations in the FGFR1-FGFR3 and TWIST genes are known to cause craniosynostosis, the former by constitutive activation and the latter by haploinsufficiency. Although clinically achieving the same end result, the premature fusion of the calvarial bones, it is not known whether these genes lie in the same or independent pathways during calvarial bone development and later in suture closure. We have previously shown that Fgfr2c is expressed at the osteogenic fronts of the developing calvarial bones and that, when FGF is applied via beads to the osteogenic fronts, suture closure is accelerated (Kim, H.-J., Rice, D. P. C., Kettunen, P. J. and Thesleff, I. (1998) Development 125, 1241-1251). In order to investigate further the role of FGF signalling during mouse calvarial bone and suture development, we have performed detailed expression analysis of the splicing variants of Fgfr1-Fgfr3 and Fgfr4, as well as their potential ligand Fgf2. The IIIc splice variants of Fgfr1-Fgfr3 as well as the IIIb variant of Fgfr2 being expressed by differentiating osteoblasts at the osteogenic fronts (E15). In comparison to Fgf9, Fgf2 showed a more restricted expression pattern being primarily expressed in the sutural mesenchyme between the osteogenic fronts. We also carried out a detailed expression analysis of the helix-loop-helix factors (HLH) Twist and Id1 during calvaria and suture development (E10-P6). Twist and Id1 were expressed by early preosteoblasts, in patterns that overlapped those of the FGF ligands, but as these cells differentiated their expression dramatically decreased. Signalling pathways were further studied in vitro, in E15 mouse calvarial explants. Beads soaked in FGF2 induced Twist and inhibited Bsp, a marker of functioning osteoblasts. Meanwhile, BMP2 upregulated Id1. Id1 is a dominant negative HLH thought to inhibit basic HLH such as Twist. In Drosophila, the FGF receptor FR1 is known to be downstream of Twist. We demonstrated that in Twist(+/)(-) mice, FGFR2 protein expression was altered. We propose a model of osteoblast differentiation integrating Twist and FGF in the same pathway, in which FGF acts both at early and late stages. Disruption of this pathway may lead to craniosynostosis.

Speech articulation after subtotal glossectomy and reconstruction with a myocutaneous flap.

Speech samples of 9 subjects (8 males, 1 female) were recorded before and 0.5-2 years after a partial glossectomy and reconstruction with a pectoralis major myocutaneous flap. A reading sample, a list of meaningful and nonsense words, and a list of sustained vowels were recorded. The speech samples were evaluated by pairs of naive listeners and using acoustic analysis of the vowel production. Each pair listened to the recordings of only one patient. Inter-rater agreement was satisfactory. The general impression of the speech outcome varied from normal to moderately impaired. The perceptually estimated impairments of speech articulation in the after/before comparisons were statistically significant. Only the first formant of the vowel /i/ (rise) and the second formant of the vowel /a/ (drop) changed significantly at the group level. There was a negative correlation (r = -0.79) between the extent of tongue resection and the drop of the second formant of the vowel /a/. The perceptual variables showed a relationship (r = 0.74-0.82) with the changes in the level of the second formant of the vowel /i/. The relationship that emerged between the perceptual estimates and the objective acoustic parameters suggests that it will be possible to develop clinically relevant test batteries for articulatory quality analysis.

Refined mapping of the Usher syndrome type III locus on chromosome 3, exclusion of candidate genes, and identification of the putative mouse homologous region.

A locus for Usher syndrome type III (USH3; MIM No. 276902) was recently assigned to a 5-cM region on chromosome 3q. We constructed a yeast artificial chromosome contig that allowed us to position novel polymorphisms in the region. These were typed in a total of 32 pedigrees from a geographically isolated Finnish founder population in which a putative single ancestral USH3 mutation segregates. A multipoint linkage analysis assigned USH3 to a 4-cM region between D3S1555 and a novel marker D3S3625. By analysis of linkage disequilibrium and historical recombinations in 77 USH3 chromosomes, the location of the Finnish USH3 mutation could be narrowed to an approximately 1-cM interval between the markers D3S1299 and D3S3625. A gene for profilin-2 (PFN2) was mapped in the vicinity and excluded as a candidate for USH3 by sequencing. The putative mouse homolog of PFN2 was mapped to mouse chromosome 3, thus suggesting a localization for the mouse homolog of USH3.

Usher's syndrome type 3 in Finland.

Usher's syndrome, type 3 (USH3) is characterized by progressive hearing loss. Usher's syndrome, type 3 has been supposed to be rare, occurring in 2% to 4% of all patients with Usher's syndrome. In a nationwide study we collected data on 229 patients with Usher's syndrome in Finland. Definite cases of USH3 were found in 30 (13%) of the 229 patients. An additional 61 patients had clinical evidence of earlier progression of their hearing impairment. We suggest that 91 (40%) of the 229 patients with Usher's syndrome represent cases of USH3.

The ophthalmological course of Usher syndrome type III.

Usher syndrome is a recessive hereditary disease group with clinical and genetical heterogeneity leading to handicapped hearing and visual loss until middle age. It is the most common cause for deaf-blindness. Three distinct phenotypes and five distinct genotypes are already known. In Finland the distribution of known Usher types is different than elsewhere. Usher syndrome type III (USH3) is common in Finland and it is thought to include 40% of patients. Progressive hearing loss is characteristic of USH3. Elsewhere USH3 has been regarded as a rarity covering only several percent of the whole Usher population. The aim of this paper is to describe, for the first time, the course of visual handicap and typical refractive errors in USH3 and compare it with other USH types. From a total patient sample consisting of 229 Finnish USH patients, 200 patients' visual findings were analyzed in a multicenter retrospective follow-up study. The average progress rate during a 10-year follow-up period in different USH types was similar. The essential progress occurred below the age of 40 and was continuous up to that age. Visual acuity dropped below 0.05 (severely impaired) at the age of 37 and the visual fields were of tubular shape without any peripheric islands at the average age of 30. Clinically significant hypermetropia with astigmatism seems to be a pathognomonic clinical sign of USH3.

Assignment of an Usher syndrome type III (USH3) gene to chromosome 3q.

Usher syndrome (USH) refers to genetically and clinically heterogeneous autosomal recessive disorders with combined visual and hearing loss. Type I (USH1) is characterized by a congenital, severe to profound hearing loss and absent vestibular function; in type II (USH2) the hearing loss is congenital and moderate to severe, and the vestibular function is normal. Progressive pigmentary retinopathy (PPR) is present in both types. A third type (USH3) differing from USH2 by the progressive nature of its hearing loss has been suggested. USH3 has previously been estimated to comprise 2% of all USH. However, based on clinical criteria, in Finland 42% of USH patients have progressive hearing loss suggesting enrichment of an USH3 gene. We excluded the four previously mapped USH regions as the site of the USH3 disease locus. Systematic search for USH3 by genetic linkage analyses in 10 multiple affected families using polymorphic microsatellite markers revealed significant linkage with markers mapping to chromosome 3q. Pairwise lod scores at zero recombination distance were 7.87 for D3S1308, and 11.29 for D3S1299, incorporating the observed linkage disequilibrium. Conventional multipoint linkage analysis gave a maximum lod score of 9.88 at D3S1299 assigning USH3 to the 5 cM interval between markers D3S1555 and D3S1279 in 3q21-25.(ABSTRACT TRUNCATED AT 250 WORDS)

Progressive hearing loss in Usher's syndrome.

In 18 patients with Usher's syndrome, progressive hearing loss was verified audiologically in eight cases. Despite poor auditory threshold values and low speech discrimination scores, there was only one patient who could not communicate with speech. The possibility of hearing impairment being mainly progressive in Usher's syndrome is discussed.

Treatment of vocal cord granuloma.

Combined surgical and conservative therapy (voice therapy, treatment of infections, allergy, oesophageal reflux, and psychogenic stress) has been used in the treatment of non-specific vocal cord granuloma. Such tumors have a great tendency to recur. The 41 patients with vocal cord granuloma in our study (4 women, 37 men, mean age 56 years) were treated at our hospital during 1980-1986. Nine patients were healed with conservative treatment, 32 were treated by laryngomicrosurgery under general anesthesia and jet-ventilation. The latter group was divided into three treatment groups; 8 of these patients were treated with cryotherapy, 9 with postoperative steroids (Prednisolone 40 mg/day in decreasing doses) and antibiotics, and 15 only with microsurgery. At some phase in their treatment 41% of the patients were able to participate in voice therapy. The most recurrences were found in the group treated with cryotherapy, 2.7 rec./pat.; 1.8 rec./pat. were found in the group that underwent surgery, and 1.7 rec./pat. among the patients treated with steroid-antibiotics. In all three groups, some patients experienced recurrences. In the cryotherapy group, however, recurrent granulomas were large and required reoperation, while those in patients treated with steroid-antibiotics were small and could be cured using conservative therapy. If granuloma does not disturb the voice, cause respiratory obstruction or demand histopathological diagnosis, surgery is contraindicated. Cryotherapy does not help traditional surgery, while steroid-antibiotics administered postoperatively seem to help the healing process.