A randomized controlled trial of the effectiveness of teacher continued professional development on student language outcomes

BACKGROUND

Continued professional development (CPD) is required for updated skills and knowledge. This study evaluates the efficacy of a CPD programme for mainstream school teachers.

AIMS

In an 11-week intervention programme, speech-language therapists (SLTs) presented the participating teachers with whole-class teaching techniques aimed at creating a language and communication-supporting classroom environment. The effects of the intervention on the language development of the students in the teachers' classes were assessed.

METHODS & PROCEDURES

A total of 211 first- and second-year students (M_age = 7;6, range = 6;5-8;9) underwent standardized language assessments of receptive and expressive language abilities before and after their teachers' participation in the CPD. The students were divided into intervention and delayed intervention groups to enable randomized intervention allocation. Linear mixed modelling was used to estimate the individual and interaction effects of group, time and demographic factors.

OUTCOMES & RESULTS

Significant effects of time, group and school, respectively, but no interaction between time and group indicates that while all students advanced between assessments, the progress was not attributable to the teachers' participation in the CPD.

CONCLUSIONS & IMPLICATIONS

Results are discussed in light of those of recent studies of universal services to support optimal language development.

WHAT THIS PAPER ADDS

What is already known on this subject Although inconclusive, previous research indicates that intervention delivered to teachers by SLTs has the potential to improve the language abilities of the students in the teachers' classrooms. What this paper adds to existing knowledge This study explored the language development of first- and second-year mainstream school students whose teachers took part in a CPD programme aimed at establishing language and communication-supporting teaching techniques. Results indicate that the development of the students' language abilities could not be attributed to the teachers' participation in the CPD. What are the potential or actual implications of the work? SLTs are often asked to guide teachers and teaching staff rather than themselves conduct individual assessments and interventions. The results of this trial can be used to inform the discussion on how to prioritize between tasks.

'It depends on who I'm with': How young people with developmental language disorder describe their experiences of language and communication in school

BACKGROUND

The risks of developmental language disorder (DLD) for both educational progress and socio-emotional development are well documented, but little is known about how children and young people with DLD experience and describe their language and communication. The need to complement experimental and quantitative studies with qualitative perspectives of the lived experience of individuals with DLD for speech and language therapists (SLT) practice has recently been foregrounded.

AIMS

To understand further the experiences of young people with DLD focusing on language and communication in a school context, and thereby contribute to the improvement of the communicative situation in school for this group. The study is guided by the following research question: How do young people diagnosed with DLD describe their experiences of language and communication in school?

METHODS & PROCEDURES

The study is based on data generated from qualitative semi-structured interviews with 23 participants diagnosed with DLD (age 13-19 years old) living in Sweden. All participants attended mainstream schools. To enable data to be collected during COVID-19 restrictions, all interviews were conducted using Zoom. Reflexive thematic analysis was used to analyse the data.

OUTCOMES & RESULTS

Four main themes related to experiences of language and communication in school were constructed from the interviews: (1) feelings of inadequacy and comparisons with others; (2) feelings of being misjudged and misunderstood; (3) the importance of feeling safe and comfortable; and (4) the significance of the social and communicative context. The results bear witness of difficult and challenging aspects related to language and communication in school, including educational, social and emotional dimensions. An important outcome of this study is how young people diagnosed with DLD describe their language and communication functioning to be dependent on both individual characteristics and abilities, as well as situational, contextual and social factors.

CONCLUSIONS & IMPLICATIONS

The results from this study show that young people with DLD can have persisting problems related to language and communication in school, including educational, social and emotional dimensions. SLT services may therefore be needed throughout the school years to ensure that students with DLD receive adequate support. In addition, support that goes beyond language abilities and targets social, contextual and emotional aspects should be considered.

WHAT THIS PAPER ADDS

What is already known on this subject Children and young people have unique knowledge about their language and communication which is instrumental for designing interventions and support strategies. Qualitative analyses of interview data have been able to identify both risk factors and protective strategies in relation to the well-being of individuals with DLD. Despite this, children and young people with DLD are rarely heard in research or clinical discussions. What this paper adds to existing knowledge In this study we listen to the voices of young people with DLD as they describe their experiences of language and communication in school. The participants describe a condition that makes them struggle to keep up with peers and puts them at risk of being misjudged by teachers, but also give examples of situations where negative consequences are hardly felt. What are the potential or actual clinical implications of this work? DLD is a complex and dynamic disorder where contextual and social factors interact with individual abilities in creating the end result. The results of the study indicate that DLD can cause persisting problems related to language and communication in school, with impact on educational, social and emotional dimensions. To counteract these effects, SLT services may be needed throughout the school years, and support that goes beyond language abilities must be considered.

Word definition skills in elementary school children - The contribution of bilingualism, cognitive factors, and social factors

Purpose: Vocabulary relates to overall language proficiency and is important for academic success. Word definition (WD) tasks can be used to assess vocabulary depth and definition skills. We investigate monolingual and bilingual children's performances on a WD task, and how bilingualism, level of parental education, school characteristics (proportion of students with Swedish as second language and proportion of parents with tertiary education), CELF-4 Core Language Score, and non-verbal IQ contribute to their performance. We also evaluate the level of difficulty of the test items and the test's internal consistency.Method: Two hundred and eight children (mean age 7:8, range 6:8-9:0) were assessed with a 10-item WD task. Amount of information included in the definitions gave the WD score and number of words with at least partially correct information gave a Word knowledge score.Result: The bilingual group had lower scores on both measures. In isolation bilingualism explained 15% of the variance of the WD score. With all background factors included, the only significant predictor was CELF-4 Core Language Score, uniquely explaining 24.3% of the variance. Response patterns on the WD score were similar between groups. Internal consistency was > α = 0.7 for both measurements.Conclusion: Bilingual children performed lower than monolingual children on a WD task, but bilingualism alone cannot explain poor results.

Evaluating the Effect of Rich Vocabulary Instruction and Retrieval Practice on the Classroom Vocabulary Skills of Children With (Developmental) Language Disorder

PURPOSE

Learning new vocabulary has been identified as a challenge for students with (developmental) language disorder ((D)LD). In this study, we evaluate the effects of two active learning methods, (a) retrieval practice (RP) and (b) rich vocabulary instruction (RVI), in a group of students with (D)LD in secondary school.

METHOD

A quasi-experimental counterbalanced within-subject design was used to compare and evaluate the effect of RP and RVI on learning Tier 2 vocabulary, with target and control words as dependent measures. Eleven students with (D)LD (M _age = 14.9 years) attending a language unit participated. RP and RVI were implemented in regular classroom activities during 16 lessons (eight lessons/instructional condition). Learning was assessed by comparing performance on a pretest session 1-2 weeks prior, with posttest performance 1 week after each instructional condition.

RESULTS

The learning gain for RP was superior to that for RVI, both with respect to the Bayesian probabilistic estimations for target words relative to control words and in direct comparison with RVI. Only weak evidence was found for RVI with respect to the Bayesian probabilistic estimations for target words relative to control words.

CONCLUSIONS

All participants showed positive learning gains following RP, whereas the outcome for RVI was more diverse. This initial work suggests that RP promotes larger learning gains relative to RVI and promotes learning across language profiles. This study extends previous studies by exploring the implementation of RP in regular classroom activities and by using more complex to-be-learned material (Tier 2 words).

Clinical Application and Psychometric Properties of a Swedish Translation of the Abbreviated Profile of Hearing Aid Benefit

BACKGROUND

The impact of hearing loss on the individual and his/her everyday life can be assessed using questionnaires with the purpose to improve rehabilitation quality. The Abbreviated Profile of Hearing Aid Benefit (APHAB) can be used to evaluate disability in everyday life associated with hearing loss. Previous studies have examined APHAB outcomes in sensorineural hearing loss and we do not know whether the type of hearing loss influence questionnaire outcomes.

PURPOSE

The purpose was to evaluate the psychometric properties of a Swedish translation of the APHAB and the influence of demographic variables on the outcome in a clinical sample.

RESEARCH DESIGN

A descriptive, cross-sectional study in a clinical sample.

STUDY SAMPLE

Forty-eight participants with no hearing aid experience seeking audiological rehabilitation for the first time. These participants represented different degrees of hearing loss and three types of hearing loss: monaural mixed, binaural mixed, and binaural sensorineural hearing loss.

DATA COLLECTION AND ANALYSIS

Pure-tone audiometry was conducted and the participants completed the unaided APHAB during their first appointment at the clinic. Psychometric properties of the questionnaire were examined and the influence of age, gender, type of hearing loss, and degree of hearing loss on APHAB scores were studied.

RESULTS

The psychometric properties indicate high test-retest reliability but there seems to be some potential issues with the properties of the reverberation (RV) subscale. The items from the RV subscale failed to load as a separate component and the internal consistency of the subscale improved by removing four items (items 1, 9, 11, and 16). With few exceptions, APHAB scores were not influenced by age, gender, or type of hearing loss. APHAB scores were generally influenced by degree of hearing loss in both the best and the worst ear.

CONCLUSION

This Swedish version of the APHAB can be additionally improved by addressing the inconsistencies found in the RV subscale by rephrasing or removing some items. The degree of hearing loss has some influence on questionnaire outcomes but not age, gender, and type of hearing loss.

Using a word association task to investigate semantic depth in swedish-speaking children with developmental language disorder

We examined word associations in Swedish children with Developmental Language Disorder (DLD) compared to their typically developing (TD) peers. Furthermore, the study aimed to explore the dimensions of vocabulary knowledge (breadth, depth, and fluency) in these children. Fifty children (15 DLD and 35 TD) participated in the study, aged six to nine years. This age span is commonly associated with substantial lexical reorganisation, by some referred to as the syntagmatic-paradigmatic shift. Fifty items from the Kent-Rosanoff list were used to elicit word associations (say the first word that comes to mind). Word associations were coded as paradigmatic (lion-tiger), syntagmatic (chair-sit), phonological (moon-poon), and other/no answer (foot-hello/bed- -). A semantic depth score (paradigmatic and syntagmatic associations) was calculated and analysed. The children with DLD showed significantly lower semantic depth scores than their TD peers, in line with previous research in English-speaking children. However, the vocabulary dimensions were uniformly affected for the DLD group, contradicting previous findings of semantic depth as a particular area of weakness in this group.

The Contribution of Bilingualism, Parental Education, and School Characteristics to Performance on the Clinical Evaluation of Language Fundamentals: Fourth Edition, Swedish

Assessment of bilingual children in only one language fails to acknowledge their distributed linguistic competence and has been shown to overidentify language disorder in bilingual populations. However, other factors, sometimes associated with bilingualism, may also contribute to low results in language assessments. Our aim was to examine the impact of these factors on language abilities. We used the Clinical Evaluation of Language Fundamentals - Fourth Edition, Swedish (CELF-4) to investigate core language abilities of 224 7- to 8-year-old children. Results showed 30 and 80% of monolinguals and bilinguals, respectively, performing more than 1 SD below the normative sample mean, calling into question the clinical utility of the test. However, participant and school characteristics provided a deeper understanding of the skewed results. In isolation, bilingualism predicted 38% of the variance in the CELF-4 Core scores. With level of parental education entered the variance explained by the model increased to 52%, but the unique contribution of bilingualism was reduced to 20%. Finally, with information added on school characteristics and enrollment in the school's recreation center the model explained an additional two percent, with the unique contribution of bilingualism further reduced to 9%. The results indicate an increased risk for low results on the CELF-4 Core when children present with multiple risk factors. This highlights the need to look beyond bilingualism in language assessment of bilingual children and adolescents and to consider other explanations to academic struggle. Available interventions must be considered and applied proportionately to their respective impact on the individual's development.

Children's development of semantic verbal fluency during summer vacation versus during formal schooling

Purpose: Children's results on school-related achievements tests, such as aspects of math, reading and writing, have been shown to decline following a lengthy summer vacation. Few studies have investigated whether this also applies to vocabulary skills. The purpose of this study is to investigate how lexical organization and retrieval, assessed by a semantic verbal fluency (SVF) task, develops during a lengthy summer vacation versus formal schooling.Method: Sixty-eight children with mean age of 7.9 (ranging from 6.5 to 9.1), were assessed pre- and post-summer vacation and post-fall semester using two SVF categories (Animals and Clothes). The number of words produced in both categories gave the total score.Results: The result of the SVF tests decreased following summer vacation. The loss was recouped at the post-fall semester assessment, but no gains compared to initial testing were shown. Neither level of parental education, general language ability, non-verbal IQ, nor bilingualism explained the variance in development during the summer vacation or the fall semester.Conclusions: Our findings indicate that a lengthy summer vacation causes a recess in the expected development of SVF ability and that this recess is recouped after a semester of formal schooling. The findings are in line with previous research indicating that summer vacation may have negative impact on the development of important scholastic abilities in children.

Monitoring progression of clinical reasoning skills during health sciences education using the case method - a qualitative observational study

BACKGROUND

Outcome- or competency-based education is well established in medical and health sciences education. Curricula are based on courses where students develop their competences and assessment is also usually course-based. Clinical reasoning is an important competence, and the aim of this study was to monitor and describe students' progression in professional clinical reasoning skills during health sciences education using observations of group discussions following the case method.

METHODS

In this qualitative study students from three different health education programmes were observed while discussing clinical cases in a modified Harvard case method session. A rubric with four dimensions - problem-solving process, disciplinary knowledge, character of discussion and communication - was used as an observational tool to identify clinical reasoning. A deductive content analysis was performed.

RESULTS

The results revealed the students' transition over time from reasoning based strictly on theoretical knowledge to reasoning ability characterized by clinical considerations and experiences. Students who were approaching the end of their education immediately identified the most important problem and then focused on this in their discussion. Practice knowledge increased over time, which was seen as progression in the use of professional language, concepts, terms and the use of prior clinical experience. The character of the discussion evolved from theoretical considerations early in the education to clinical reasoning in later years. Communication within the groups was supportive and conducted with a professional tone.

CONCLUSIONS

Our observations revealed progression in several aspects of students' clinical reasoning skills on a group level in their discussions of clinical cases. We suggest that the case method can be a useful tool in assessing quality in health sciences education.

ELAN Analysis Companion (EAC): A Software Tool for Time-course Analysis of ELAN-annotated Data

LAN is a widely used and free (in both senses) annotation software for behavioral or other events that unfold over time. We report on and release a stand-alone program that expands on ELAN's capabilities in two ways: 1) it allows the researcher to plot and export time-course analysis data directly from ELAN's native annotation files, allowing for hassle-free data extraction in the time domain, e.g. for visual-world paradigm studies; and 2) it allows the researcher to weight ELAN's built-in annotator reliability rating based on the duration of the coded events. This software is released under an open license.

Executive functions in mono- and bilingual children with language impairment - issues for speech-language pathology

The clinical assessment of language impairment (LI) in bilingual children imposes challenges for speech-language pathology services. Assessment tools standardized for monolingual populations increase the risk of misinterpreting bilingualism as LI. This Perspective article summarizes recent studies on the assessment of bilingual LI and presents new results on including non-linguistic measures of executive functions in the diagnostic assessment. Executive functions shows clinical utility as less subjected to language use and exposure than linguistic measures. A possible bilingual advantage, and consequences for speech-language pathology practices and future research are discussed.

Working memory and referential communication-multimodal aspects of interaction between children with sensorineural hearing impairment and normal hearing peers

Whereas the language development of children with sensorineural hearing impairment (SNHI) has repeatedly been shown to differ from that of peers with normal hearing (NH), few studies have used an experimental approach to investigate the consequences on everyday communicative interaction. This mini review gives an overview of a range of studies on children with SNHI and NH exploring intra- and inter-individual cognitive and linguistic systems during communication. Over the last decade, our research group has studied the conversational strategies of Swedish speaking children and adolescents with SNHI and NH using referential communication, an experimental analog to problem-solving in the classroom. We have established verbal and non-verbal control and validation mechanisms, related to working memory capacity and phonological short term memory. We present main findings and future directions relevant for the field of cognitive hearing science and for the clinical and school-based management of children and adolescents with SNHI.

Coordination of gaze and speech in communication between children with hearing impairment and normal-hearing peers

PURPOSE

To investigate gaze behavior during communication between children with hearing impairment (HI) and normal-hearing (NH) peers.

METHOD

Ten HI-NH and 10 NH-NH dyads performed a referential communication task requiring description of faces. During task performance, eye movements and speech were tracked. Using verbal event (questions, statements, back channeling, and silence) as the predictor variable, group characteristics in gaze behavior were expressed with Kaplan-Meier survival functions (estimating time to gaze-to-partner) and odds ratios (comparing number of verbal events with and without gaze-to-partner). Analyses compared the listeners in each dyad (HI: n = 10, mean age = 12;6 years, mean better ear pure-tone average = 33.0 dB HL; NH: n = 10, mean age = 13;7 years).

RESULTS

Log-rank tests revealed significant group differences in survival distributions for all verbal events, reflecting a higher probability of gaze to the partner's face for participants with HI. Expressed as odds ratios (OR), participants with HI displayed greater odds for gaze-to-partner (ORs ranging between 1.2 and 2.1) during all verbal events.

CONCLUSIONS

The results show an increased probability for listeners with HI to gaze at the speaker's face in association with verbal events. Several explanations for the finding are possible, and implications for further research are discussed.

Impact of cognitive and linguistic ability on gaze behavior in children with hearing impairment

In order to explore verbal-nonverbal integration, we investigated the influence of cognitive and linguistic ability on gaze behavior during spoken language conversation between children with mild-to-moderate hearing impairment (HI) and normal-hearing (NH) peers. Ten HI-NH and 10 NH-NH dyads performed a referential communication task requiring description of faces. During task performance, eye movements and speech were tracked. Cox proportional hazards regression was used to model associations between performance on cognitive and linguistic tasks and the probability of gaze to the conversational partner's face. Analyses compare the listeners in each dyad (HI: n = 10, mean age = 12; 6 years, SD = 2; 0, mean better ear pure-tone average 33.0 dB HL, SD = 7.8; NH: n = 10, mean age = 13; 7 years, SD = 1; 11). Group differences in gaze behavior - with HI gazing more to the conversational partner than NH - remained significant despite adjustment for ability on receptive grammar, expressive vocabulary, and complex working memory. Adjustment for phonological short term memory, as measured by non-word repetition, removed group differences, revealing an interaction between group membership and non-word repetition ability. Stratified analysis showed a twofold increase of the probability of gaze-to-partner for HI with low phonological short term memory capacity, and a decreased probability for HI with high capacity, as compared to NH peers. The results revealed differences in gaze behavior attributable to performance on a phonological short term memory task. Participants with HI and low phonological short term memory capacity showed a doubled probability of gaze to the conversational partner, indicative of a visual bias. The results stress the need to look beyond the HI in diagnostics and intervention. Acknowledgment of the finding requires clinical assessment of children with HI to be supported by tasks tapping phonological processing.

Timing of gazes in child dialogues: a time-course analysis of requests and back channelling in referential communication

BACKGROUND

This study investigates gaze behaviour in child dialogues. In earlier studies the authors have investigated the use of requests for clarification and responses in order to study the co-creation of understanding in a referential communication task. By adding eye tracking, this line of research is now expanded to include non-verbal contributions in conversation.

AIMS

To investigate the timing of gazes in face-to-face interaction and to relate the gaze behaviour to the use of requests for clarification.

METHODS & PROCEDURES

Eight conversational pairs of typically developing 10-15 year olds participated. The pairs (director and executor) performed a referential communication task requiring the description of faces. During the dialogues both participants wore head-mounted eye trackers. All gazes were recorded and categorized according to the area fixated (Task, Face, Off). The verbal context for all instances of gaze at the partner's face was identified and categorized using time-course analysis.

OUTCOMES & RESULTS

The results showed that the executor spends almost 90% of the time fixating the gaze on the task, 10% on the director's face and less than 0.5% elsewhere. Turn shift, primarily requests for clarification, and back channelling significantly predicted the executors' gaze to the face of the task director. The distribution of types of requests showed that requests for previously unmentioned information were significantly more likely to be associated with gaze at the director.

CONCLUSIONS & IMPLICATIONS

The study shows that the executors' gaze at the director accompanies important dynamic shifts in the dialogue. The association with requests for clarification indicates that gaze at the director can be used to monitor the response with two modalities. Furthermore, the significantly higher association with requests for previously unmentioned information indicates that gaze may be used to emphasize the verbal content. The results will be used as a reference for studies of gaze behaviour in clinical populations with hearing and language impairments.

'You sometimes get more than you ask for': responses in referential communication between children and adolescents with cochlear implant and hearing peers

BACKGROUND

This study investigates responses to requests for clarification in conversations between children/adolescents with cochlear implant (CI) and normally hearing peers. Earlier studies have interpreted a more frequent use of requests of confirmation (yes/no interrogatives) in the CI group as a conversational strategy used to prevent communication breakdowns and control the development of the conversation. This study provides a continuation of this line of research, now focusing on responses to requests for clarification.

AIMS

The aim was to examine the type and distribution of responses to requests for clarification in a referential communication task. In addition, we analysed the compliance between the type of response and the type of request as a measure of mutual adaptation.

METHODS & PROCEDURES

Twenty-six conversational pairs aged 10-19 years participated: 13 pairs consisting of a child/adolescent with CI (CI) and a conversational partner (CIP); and 13 pairs consisting of a normally hearing control (NH) and a conversational partner (NHP). The pairs performed a referential communication task requiring the description of faces. All occurrences of requests for clarification and their responses in the dialogues were identified and categorized. We also analysed how the different types of requests and responses were combined and the type-conformity of the responses to requests for confirmation.

OUTCOMES & RESULTS

The results showed no significant group differences regarding type, distribution or type-conformity of responses. In all four groups (CI, CIP, NH and NHP), a discrepancy between the request and the response was found, indicating that the response provided information that was not explicitly requested. Requests for confirmation constituted 78-90% of the requests, whereas only 54-61% of responses were confirmations. Conversely, the proportion of requests for elaboration was 6-15%, whereas the proportion of elaborated responses was 34-40%.

CONCLUSIONS & IMPLICATIONS

The children/adolescents with CI contribute equally to the conversation regarding type and distribution of responses to requests for clarification. The frequent use of elaborated responses indicates common ground for the conversational partners and a shared understanding of the objective of the task. The context creates facilitative conditions, with positive interactional consequences. The results have implications for the design of intervention, where tasks such as this can be used to make children with CI more aware of the role of questioning strategies in interaction.

Homozygosity for the transthyretin-Met30-gene in seven individuals with familial amyloidosis with polyneuropathy detected by restriction enzyme analysis of amplified genomic DNA sequences

Familial amyloidotic polyneuropathy (FAP) with a mutation in position 30 of transthyretin (TTR) (previously called prealbumin) is an autosomal dominant inherited disorder characterized by varying degrees of peripheral neuropathy, nephropathy, gastrointestinal problems, and vitreous amyloid. We have earlier diagnosed homozygosity for the TTR-Met30-gene using Southern analysis in four Swedish individuals. We have found it possible to detect homozygosity for the Met-30 mutation by amplifying discrete regions of the TTR-gene using polymerase chain reaction (PCR), and the amplification products restricted with NsiI analysed by gel electrophoresis. Clinical data on seven homozygous individuals, including three new cases, are presented.

A molecular model of the amyloid fibril

We have investigated the ultrastructure of the homozygous amyloid fibrils from the vitreous humour of patients with Met30 familial amyloidotic polyneuropathy (FAP) by high-resolution electron microscopy and X-ray diffraction using synchrotron radiation. Image reconstruction of thin sections of Met30 FAP fibrils shows that they are composed of four parallel protofilaments, 50-60 A in diameter, arranged in a square around a hollow centre. The X-ray diffraction patterns are consistent with the presence in the protofilaments of a repeating unit of 24 beta-strands forming a continuous beta-sheet extended along the fibre axis, with the beta-strands perpendicular to the axis. We have characterized this repeat unit as one turn of a beta-sheet helix. This newly-described helix reconciles the classical cross-beta structure of amyloid with the twisted beta-sheet that is known to be the most stable form of the structure. All four beta-sheets composing the protofilament twist around a single helical axis which is coincident with the axis of the protofilament. Other amyloid diffraction patterns are similar to that of FAP, suggesting that the beta-sheet helix may be the generic core structure of amyloid.

Impact of homozygosity for an amyloidogenic transthyretin mutation on phenotype and long term outcome

Although amyloidogenic transthyretin (ATTR) mutations are common in several populations, such as black Americans, the small number of diagnosed patients homozygous for TTR amyloid and the short follow up in most studies has until now prevented an analysis of their phenotype. In Sweden, nine homozygous patients from eight families carrying the ATTR mutation Val30Met, which gives rise to fatal neuropathic amyloidosis (FAP), have been identified and have now been followed for up to 15 years. This has enabled an analysis of the phenotype of homozygous patients. Genetic testing and detection of amyloid deposits in the vitreous body or in intestinal or skin biopsies confirmed the diagnosis in all patients. The patients' symptoms were obtained from medical records. For comparison, we used a group of 35 heterozygous non-transplanted patients with FAP (18 men and 17 women), who had been evaluated at the Department of Medicine, Umeå University Hospital before their deaths. Vitreous amyloidosis was the most prevalent symptom in the homozygous group, and in two patients it was the only manifestation of the disease during their lifetime. The age at onset was not different from that of heterozygous patients, and their survival tended not to be shorter but actually longer than for heterozygotes. Homozygosity for the mutation associated with FAP, ATTR Val30Met, does not implicate a more severe phenotype for Swedish patients. The most common symptom was vitreous opacity, which may be the only manifestation of the disease. These findings point to the possibilities of different pathways for amyloid formation, or the presence of hitherto unknown genes operating in amyloid formation.

Ocular phenotype of bothnia dystrophy, an autosomal recessive retinitis pigmentosa associated with an R234W mutation in the RLBP1 gene

OBJECTIVE

To describe the phenotype of Bothnia dystrophy, an autosomal recessive retinal dystrophy with an R234W mutation in the RLBP1 gene encoding cellular retinaldehyde-binding protein.

DESIGN

Medical records were reviewed retrospectively. Ophthalmologic examination, including kinetic perimetry and, in selected cases, adaptometry, color vision tests, fluorescein angiography, and electrophysiologic studies, was performed. The study included 24 individuals, all homozygous for an R234W mutation in the RLBP1 gene.

RESULTS

Patients typically show night blindness from early childhood. In young adults, retinitis punctata albescens was observed, followed by macular degeneration and a decrease in visual acuity that led to legal blindness in early adulthood. Dark adaptometry and electrophysiologic testing showed an initial loss of rod function followed by a progressive reduction of the cone responses in older ages.

CONCLUSIONS

Bothnia dystrophy is a unique retinal dystrophy belonging to the rod-cone dystrophies and has a high prevalence in northern Sweden. Fifty-seven cases of Bothnia dystrophy have been diagnosed, indicating a prevalence as high as 1 per 4500 population in the geographic area studied. A defect ability of mutated cellular retinaldehyde-binding protein to bind retinoid probably explains the defect rod function followed by central and peripheral degeneration.

CLINICAL RELEVANCE

Retinal dystrophies associated with other mutations of the RLBP1 gene, including retinitis pigmentosa of Bothnia type, might account for a considerable number of cases of autosomal recessive retinitis pigmentosa in other geographic areas as well.

Autosomal dominant cone-rod dystrophy due to a missense mutation (R838C) in the guanylate cyclase 2D gene (GUCY2D) with preserved rod function in one branch of the family

We present the clinical and molecular genetic features of a large multi-generation Norwegian family with dominant cone-rod dystrophy. Ophthalmological evaluation including electroretinography showed cone dysfunction in younger patients, with rod dysfunction becoming apparent at more advanced stages of the disease. In one branch of the family, cone degeneration remained the only manifestation despite advancing age. Linkage analysis mapped the disease gene in this family to 17p12-p13, a chromosome region previously linked to cone-rod dystrophy in a Swedish family (CORD5). A maximum LOD score of 3.25 (straight theta = 0.00) for marker D17S1844 was obtained. Mutation analysis of the guanylate cyclase 2D gene (GUCY2D, MIM 600179, previously called RETGC1), located at 17p12-p13, showed a missense mutation (R838C) in exon 13, that co-segregated with the eye disease in the family. Our suspicion of the possibility of an interrelationship between the Swedish CORD5 family and the present family, both originating from Northern Scandinavia, initiated the linkage analysis in the Norwegian family. The R838C missense mutation was not, however, detected in the Swedish patients, strongly suggesting no relationship between these two families. The long-term ophthalmological evaluation in this large four-generation family, combined with the identification of the disease-causing mutation, provide critical information for refining the classification, prognosis, and genetic counselling of patients with cone-rod dystrophies.

Enhancement of AA-amyloid formation in mice by transthyretin amyloid fragments and polyethylene glycol

The mechanism behind amyloid formation is unknown in all types of amyloidosis. Several substances can enhance amyloid formation in animal experiments. To induce secondary systemic amyloid (AA-type amyloid) formation, we injected silver nitrate into mice together with either amyloid fibrils obtained from patients with familial polyneuropathy (FAP) type I or polyethylene glycol (PEG). Mice injected with silver nitrate only served as controls. Amyloid deposits were detectable at day 3 in animals injected with amyloid fibrils and in those injected with PEG, whereas in control mice, deposits were not noted before day 12. Our results indicate that amyloid fibrils from FAP patients and even a non-sulfate containing polysaccharide (PEG) have the potential to act as amyloid-enhancing factors.

Genomic organization of human DLG4, the gene encoding postsynaptic density 95

We have determined the exon-intron organization and characterized the 5'-flanking promoter region of DLG4. Encompassing approximately 30 kb, the DLG4 locus is composed of 22 exons that range in size from 28 to 1,218 nucleotides. All splice sites conform to the GT-AG rule, except for the splice acceptor site of intron 5, which is TG instead of AG. Three different exons of DLG4 were found to be alternatively spliced in a subset of tissues. Two of these variants result in altered postsynaptic density 95 (PSD95) isoforms that dramatically truncate the protein. The third splicing variant represents an extension of exon 4 that encodes an additional 33-amino acid segment. Analysis of the core promoter region for DLG4 suggests that the expression of this gene is controlled by a TATA-less promoter using a single transcriptional start site embedded within a CpG island. DLG4 maps to a region on chromosome 17p13.1 known to contain a locus for autosomal dominant cone dystrophy 5. Scanning for mutations in the DLG4 coding region and splice sites was performed in 15 cone dystrophy patients, including probands from five families showing linkage to the DLG4 region. No disease-causing mutations were identified in any patients, suggesting that DLG4 is not the causative gene for this genetic eye disorder.

What is the role of giant cells in AL-amyloidosis?

AL-amyloidosis is one of the most common amyloidoses and can be found in a localized and a systemic form. The precursor protein is an immunoglobulin light chain which as AL-protein in both localized and systemic AL-amyloidosis shows the same pattern of fragmentation and changes of primary structure. In this work it is shown that that there is a difference between localized and systemic amyloidosis in respect to accompanying giant cells which constantly are found associated with amyloid deposits in localized AL-amyloidosis. In addition, giant cells were found together with amyloid deposits in lymph nodes of some cases of systemic AL-amyloidosis. Based on these findings and electron microscopic studies, it is discussed whether the giant cells actively participate in amyloid fibril formation by uptake and modification of the precursor protein or the giant cells are part of a foreign body reaction. Included in this work are two new cases of localized lung (lambda I) and ureteric (kappa I) AL-amyloidosis.

Analysis of transthyretin amyloid fibrils from vitreous samples in familial amyloidotic polyneuropathy (Val30Met)

The aim of the present study was to analyze the forms of wild type and mutated monomeric transthyretin (Val30Met) in the amyloid fibrils of patients with familial amyloidotic polyneuropathy by electrospray ionization mass spectrometry (ESI-MS). The solubility of amyloid fibrils from the vitrectomized samples was examined to determine the appropriate solution for ESI-MS. ESI-MS analysis revealed that heterozygotic Val30Met amyloid fibrils contained 14.6 +/- 7.5% normal TTR. In all samples, 3 different types of variant ATTR could be identified: Full length ATTR, and -57, and -157 (or 156) Da from ATTR Val30Met were found. The two peaks showing -57, and -157 (or 156) Da from ATTR Val30Met corresponded to the -Gly, and -Gly-Pro sequences of ATTR Val30Met from the N-terminal. The results illustrate the heterogeneity of ATTR amyloid deposits and this method may be very useful for analyzing amyloid fibrils in ATTR related amyloidosis.

The mutation spectrum of the bestrophin protein--functional implications

Best's macular dystrophy (BMD), also known as vitelliform macular degeneration type 2 (VMD2; OMIM 153700), is an autosomal dominant form of macular degeneration with mainly juvenile onset. BMD is characterized by the accumulation of lipofuscin within and beneath the retinal pigment epithelium. The gene causing the disease has been localized to 11q13 by recombination breakpoint mapping. Recently, we have identified the causative gene encoding a protein named bestrophin, and mutations have been found mainly to affect residues that are conserved from a family of genes in Caenorhabditis elegans. The function of bestrophin is so far unknown, and no reliable predictions can be made from sequence comparisons. We have investigated the bestrophin gene in 14 unrelated Swedish, Dutch, Danish, and Moroccan families affected with BMD and found eight new mutations. Including the previously published mutations, 15 different missense mutations have now been detected in 19 of the 22 families with BMD investigated by our laboratory. Interestingly, the mutations cluster in certain regions, and no nonsense mutations or mutations causing frame-shifts have been identified. Computer simulations of the structural elements in the bestrophin protein show that this protein is probably membrane bound, with four putative transmembrane regions.

Bothnia dystrophy caused by mutations in the cellular retinaldehyde-binding protein gene (RLBP1) on chromosome 15q26

PURPOSE

To determine the chromosomal location and to identify the gene causing a type of retinitis punctata albescens, called Bothnia dystrophy, found in a restricted geographic area in northern Sweden.

METHODS

Twenty patients from seven families originating from a restricted geographic area in northern Sweden were clinically examined. Microsatellite markers were analyzed in all affected and unaffected family members. Direct genomic sequencing of the gene encoding cellular retinaldehyde-binding protein was performed after the linkage analysis had been completed.

RESULTS

Affected individuals showed night blindness from early childhood with features consistent with retinitis punctata albescens and macular degeneration. The responsible gene was mapped to 15q26, the same region to which the cellular retinaldehyde-binding protein gene has been assigned. Subsequent analysis showed all affected patients were homozygous for a C to T substitution in exon 7 of the same gene, leading to the missense mutation Arg234Trp. Analysis of marker haplotypes suggested that all cases had a common ancestor who carried the mutation.

CONCLUSIONS

A missense mutation in the cellular retinaldehyde-binding protein gene is the cause of Bothnia dystrophy. The disease is a local variant of retinitis punctata albescens that is common in northern Sweden due to a founder mutation.

Analysis of x-ray diffraction patterns from amyloid of biopsied vitreous humor and kidney of transthyretin (TTR) Met30 familial amyloidotic polyneuropathy (FAP) patients: axially arrayed TTR monomers constitute the protofilament

Familial amyloidotic polyneuropathy (FAP) is characterized by deposits of amyloid fibers in which the major protein component is transthyretin (TTR). Nearly fifty mutations have been reported for the TTR in hereditary FAP. Protein crystallography of mutant TTRs has shown that the molecular structures of the variant molecules are similar to those found in the wild type. On this basis, the FAP fibers were initially proposed to consist of native-like TTR tetramers. In the current paper, we used x-ray fiber diffraction to study the structure of FAP fibers from biopsy samples of vitreous humor and kidney. The reflections of the vitreous sample showed a cross-beta diffraction pattern. All the meridional reflections were indexed by a one-dimensional, 29 A-period lattice, and the equatorial reflections were indexed by an apparent one-dimensional 67 A-period lattice. The x-ray intensity distribution indicated that the unit structure, which is similar to a TTR monomer, is composed of a pair of beta-sheets consisting of four hydrogen-bonded beta-chains per sheet, with the beta-chains oriented approximately normal to the fiber axis. The axial disposition of these units, with a 29 A-period, constitutes the protofilament; and a tetrameric lateral assembly of the protofilaments containing the core domain of the approximately 20 A-wide beta-sheet structure constitutes the FAP amyloid fiber. An inter-fiber separation of 75 A in these concentrated samples accounts for the apparent one-dimensional lattice perpendicular to the fiber axis. In the delipidated kidney FAP sample, the diffraction pattern indicated a pair of beta-sheets, suggesting that the protofilament structure in kidney is similar to that in vitreous humor. In the non-delipidated sample the successive sharp reflections indexed to a one-dimensional, 48.9 A-lattice, and the electron density projection showed a density elevation at the center of a lipid bilayer. This suggests that lipid may be associated with the monomeric TTR in the kidney FAP protofilament.

A Swedish family with a mutation in the peripherin/RDS gene (Arg-172-Trp) associated with a progressive retinal degeneration

PURPOSE

To clinically characterize a Swedish family with autosomal dominant retinitis pigmentosa due to a mutation, Arg-172-Trp, in the peripherin/RDS gene.

METHODS

Full clinical evaluation including kinetic visual field testing, measurement of dark-adaptation threshold, and full-field electroretinography in seven patients with autosomal dominant retinitis pigmentosa and three healthy family members. Denaturing gradient gel electrophoresis (DGGE) was used for mutation screening in seven patients and six healthy members of the family.

RESULTS

Three of four siblings from the middle generation and four of the younger generation were heterozygous for the peripherin /RDS Arg-172-Trp mutation. The mutation segregated with the disease. Visual acuity decreased progressively with age and visual fields were moderately constricted in young patients, while central scotoma and constriction of the fields were detected in the family members above 50 years of age. The results from full-field electrography were comparable with a widespread retinal degeneration.

CONCLUSIONS

Earlier, the peripherin/RDS Arg-172-Trp mutation was associated primarily with a macular degeneration phenotype. One previous study indicated that this mutation also can give rise to a degeneration of the more peripheral parts of the retina. In the present study, a widespread retinal degeneration is seen in the patients above 50 years of age, carrying the Arg-172-Trp mutation.

Identification of the gene responsible for Best macular dystrophy

Best macular dystrophy (BMD), also known as vitelliform macular dystrophy (VMD2; OMIM 153700), is an autosomal dominant form of macular degeneration characterized by an abnormal accumulation of lipofuscin within and beneath the retinal pigment epithelium cells. In pursuit of the disease gene, we limited the minimum genetic region by recombination breakpoint analysis and mapped to this region a novel retina-specific gene (VMD2). Genetic mapping data, identification of five independent disease-specific mutations and expression studies provide evidence that mutations within the candidate gene are a cause of BMD. The 3' UTR of the candidate gene contains a region of antisense complementarity to the 3' UTR of the ferritin heavy-chain gene (FTH1), indicating the possibility of antisense interaction between VMD2 and FTH1 transcripts.

Expanded CAG repeats in Swedish spinocerebellar ataxia type 7 (SCA7) patients: effect of CAG repeat length on the clinical manifestation

Spinocerebellar ataxia 7 (SCA7) is a neurodegenerative disorder characterized by degeneration of the cerebellum, brainstem and retina. The gene responsible for SCA7, located on chromosome 3p, recently was cloned and shown to contain a CAG repeat in the coding region of the gene, that is expanded in SCA7 patients of French origin. We examined the SCA7 repeat region in four Swedish SCA7 families as well as in 57 healthy controls. All Swedish SCA7 patients exhibited expanded CAG repeats with a strong negative correlation between repeat size and age of onset. The repeat length in SCA7 patients ranged from 40 to >200 repeats. The largest expansion was observed in a juvenile case with an age of onset of 3 months, and represents the longest polyglutamine stretch ever reported. In patients with 59 repeats or more, visual impairment was the most common initial symptom observed, while ataxia predominates in patients with <59 repeats. Two of the Swedish SCA7 families analysed in this study were shown to be related genealogically. The other two SCA7 families could not be traced back to a common ancestor. All four families shared the same allele on the disease chromosome at a locus closely linked to SCA7, suggesting the possibility of a founder effect in the Swedish population.

Refined genetic localization of the Best disease gene in 11q13 and physical mapping of linked markers on radiation hybrids

Best's macular dystrophy, also known as vitelliform macular degeneration type 2 (VMD-2), is an autosomal dominant eye disorder that causes reduced visual acuity. It generally manifests itself in the teenage years. The gene mutated in VMD-2 patients may provide valuable insight into the biological mechanisms of the far more common disorder age-related macular degeneration. The VMD-2 gene has been localized to 11q13 between UGB and Fc epsilon RI. In order to clone the gene positionally, a large Swedish VMD-2 family dating back to the 17th century was studied for recombinations. Since the last study, another 40 microsatellite markers have been analyzed in the family; the closest centromeric flanking marker, D11S4076, revealed two recombinations and the closest telomeric flanking marker, UGB, revealed one recombination. The recombinations have occurred in affected individuals, which eliminates the potential problem of reduced penetrance. The order and physical distance between 22 markers located at proximal 11q13 were analyzed on the G3 Stanford radiation-reduced cell hybrids. The data suggest that the VMD-2 region flanked by the microsatellite markers D11S4076 and UGB is approximately 980 kb.

Angioid streaks are part of a familial syndrome of dyserythropoietic anaemia (CDA III)

Congenital dyserythropoietic anaemia type III (CDA III) is a rare disease inherited in an autosomal dominant way and characterized by mild to moderate haemolytic anaemia. Most patients are adapted to their disease and have no or few complaints. Bone marrow examination shows a characteristic picture with erythroid hyperplasia and multinucleate erythroblasts. 20% of patients in a Swedish family affected with the CDA III condition have monoclonal gammopathy or multiple myeloma. By linkage and recombination analysis in the same family, the gene linked to the CDA III condition (CDAN3) has been located to chromosome 15q22. In this paper we report the observation of visual disturbances with macular degeneration and angioid streaks in six patients with CDA III and discuss the apparent association between CDA III, angioid streaks and monoclonal gammopathy. We suggest that this triad forms a previously unreported syndrome.

Characterization of two highly amyloidogenic mutants of transthyretin

The plasma protein transthyretin (TTR) has the potential to form amyloid under certain conditions. More than 50 different point mutations have been associated with amyloid formation that occurs only in adults. It is not known what structural changes are introduced into the structure of this otherwise stable molecule that results in its aggregation into insoluble amyloid fibrils. On the basis of calculations of the frequency of known mutations over the polypeptide, we have constructed two mutants in the D-strand of the polypeptide. These molecules, containing either a deletion or a substitution at amino acid positions 53-55, were unstable and spontaneously formed aggregates upon storage in TBS (pH 7.6). The precipitates were shown to be amyloid by staining with thioflavin T and Congo Red. Their ultrastructure was very similar to that of amyloid fibrils deposited in the vitreous body of patients with familial amyloidotic polyneuropathy type 1 with an amino acid replacement in position 30 (TTRmet30). Like amyloid isolated from the vitreous body of the eye, the amyloid precipitates generated from the TTR mutants exposed a trypsin cleavage site between amino acid residues 48 and 49, while plasma TTRmet30 isolated from amyloidosis patients as well as wild-type TTR only showed minor trypsin sensitivity. Our data indicate that the mutants we have constructed are similar to amyloid precursors or may share structural properties with intermediates on a pathway leading to amyloid deposits of plasma TTR.

Muscle morphology and mitochondrial investigations of a family with autosomal dominant cerebellar ataxia and retinal degeneration mapped to chromosome 3p12-p21.1

The autosomal dominant cerebellar ataxias (ADCA) are a group of neurodegenerative disorders with ataxia and dysarthria as early and dominant signs. In ADCA type II, retinal degeneration causes severe visual impairment. ADCA type II has recently been mapped to chromosome 3p by three independent groups. In the family with ADCA type II studied here, the disease has been mapped to chromosome 3p12-p21.1. Histochemical examination of muscle biopsies in 5 cases showed slight neurogenic atrophy and irregular lobulated appearance or focal decreases of enzyme activity when staining for NADH dehydrogenase, succinic dehydrogenase and cytochrome oxidase. Ragged-red fibres were scarce. Electron microscopic examination showed uneven distribution of mitochondria with large fibre areas devoid of mitochondria and/or large subsarcolemmal accumulations of small rounded mitochondria, and frequent autophagic vacuoles. These vacuoles contained remnants of multiple small rounded organelles, possibly mitochondria, and had a remarkably consistent ultrastructural appearance. Biochemical investigation of mitochondrial function showed reduced activity of complex IV and slightly reduced activity of complex I in the respiratory chain in a severely affected child while no abnormalities were found in his affected uncle.

A new simple and rapid screening method for variant transthyretin-related amyloidosis

To screen for transthyretin (TTR) related amyloidosis rapidly and reliably, we have developed a new method using a centrifugal concentrator device and electrospray ionization mass spectrometry (ESI-MS). Only 50 microliters of serum is needed for the analysis. After preparation of the samples with anti-TTR antibody they were passed through a 1000 kDa cut off centrifugal concentrator which retained the antibody. By analyzing the obtained filtrate with ESI-MS, variant forms of TTR was detected. TTR (Met30), with a molecular weight 32.0 Da higher than the normal form of TTR, was found in all FAP patients examined. In 3 liver transplanted FAP patients, the abnormal peaks had disappeared. In conclusion, The TTR Met30 mutation was easily detected in serum samples by electrospray ionization mass spectrometry after centrifugal concentration. The proposed method is simple to perform, as no HPLC is required, and offers a possibility to screen populations for TTR related amyloidosis.

Primary localized amyloidosis of the eyelid: two cases of immunoglobulin light chain-derived proteins, subtype lambda V respectively lambda VI

Primary localized amyloidosis has been described in many different organs in the body. Studies by immunohistochemical techniques have suggested an immunoglobulin light chain origin of the amyloid material. Only in a limited number of cases has the amyloid protein been characterized by amino acid sequence analysis as subtypes of immunoglobulin light chain or heavy chain. In this report, two cases of primary localized amyloidosis of the eyelid are presented. The amyloid substance has been extracted and a major fibril protein subjected to amino acid sequence analysis. Both amyloid proteins were part of the variable region of immunoglobulin light chains, subtype lambda V and subtype lambda VI, respectively. While lambda VI has been shown to be a common subtype in systemic immunoglobulin light chain-amyloidosis, it has never been demonstrated in localized amyloid. Very few lambda V immunoglobulin light chains have been characterized and the subgroup has never been found in amyloid before.

A gene for autosomal dominant progressive cone dystrophy (CORD5) maps to chromosome 17p12-p13

Inherited retinal dystrophy is a common cause of visual impairment. Cone dystrophy affects the cone function and is manifested as progressive loss of the central vision, defective color vision, and photophobia. Linkage was demonstrated between progressive cone dystrophy (CORD5) and genetic markers on chromosome 17p12-p13 in a five-generation family. Multipoint analysis gave a maximum lod score of 7.72 at the marker D17S938. Recombinant haplotypes in the family suggest that the cone dystrophy locus is located in a 25-cM interval between the markers D17S926/D17S849 and D17S804/D17S945. Furthermore, one recombination was detected between the disease locus and a microsatellite marker in the candidate gene RCV1, encoding the retinal protein recoverin. Two additional candidate genes encoding retinal guanylate cyclase (GUC2D) and pigment epithelium-derived factor (PEDF) are located at 17p13.1. Moreover, loci for retinitis pigmentosa and Leber congenital amaurosis have been mapped to the same region. Identification of the cone dystrophy locus may be of importance not only for identifying functional genes in the cone system, but also for identifying genes for other retinal disorders.

Ocular amyloidosis, with special reference to the hereditary forms with vitreous involvement

The complex of diseases referred to as amyloidosis is characterized by the deposition of amyloid substance in various tissues. The amyloid protein differs in the various forms of amyloidosis. This variation is the basis of the differences in affected tissues and subsequent clinical dissimilarities. Vitreous involvement in amyloidosis seems to be especially linked to some of the hereditary neuropathies associated with the amyloid protein transthyretin. Characterization of the amyloid proteins during recent decades has allowed a chemical and immunologic classification of amyloid fibrils. This paper presents the basis for classification of amyloidosis, reviews the literature on ocular amyloidosis, with special reference to vitreous involvement, and summarizes clinical findings and frequency of vitreous amyloid involvement in Swedish patients with familial amyloidotic polyneuropathy.

Localization of autosomal dominant cerebellar ataxia associated with retinal degeneration and anticipation to chromosome 3p12-p21.1

We present linkage analysis on a large Swedish five-generation family of 15 affected individuals with autosomal dominant cerebellar ataxia (ADCA) associated with retinal degeneration and anticipation. Common clinical signs in this family include ataxia, dysarthria and severely impaired vision with the phenotype ADCA type II. Different subtypes of ADCA have proven difficult to classify clinically due to extensive phenotypic variability within and between families. Genetic analysis of a number of ADCA type I families shows that heterogeneity exists also genetically. During the last few years several types of ADCA type I have been localized and to date six genetically distinct forms have been identified including SCA1 (6p), SCA2 (12q), SCA3 and Machado-Joseph disease (MJD) (14q), SCA4 (16q), and finally SCA5 (11). We performed a genome-wide search of the Swedish ADCA type II family using a total of 270 microsatellite markers. Positive lod scores were obtained with a number of microsatellite markers located on chromosome 3p12-p21.1. Three markers gave lod scores over 3 with a maximum lod score of 4.53 achieved with the marker D3S1600. The ADCA type II gene could be restricted to a region of 32 cM by the markers D3S1547 and D3S1274.

Fine mapping of Best's macular dystrophy localizes the gene in close proximity to but distinct from the D11S480/ROM1 loci

The Best's macular dystrophy (BMD) gene has previously been mapped to the 11q13 region. In this study, recombination data localizes the BMD gene to the 6-cM genetic interval between the markers Fc epsilon RI and D11S480/ROM1 in a large Swedish 12-generation BMD family. Mutation analyses of the candidate gene ROM1 did not reveal any mutations that could explain the disease phenotype. However, one recombination event between intragenic ROM1 polymorphisms and the BMD phenotype was detected. Therefore, it is highly unlikely that mutations in the ROM1 gene cause BMD. Identification of the disease gene will elucidate the pathophysiological mechanism in BMD, which may also be of importance in other retinopathies such as age-related macular degeneration.

Familial amyloidotic polyneuropathy in Sweden: geographical distribution, age of onset, and prevalence

Familial amyloidotic polyneuropathy (FAP) in Swedish patients is associated with the same transthyretin mutation (TTRMet30) as in Portuguese, Japanese, Brazilian and Majorcan patients. Yet, the age of onset of FAP is much later in Sweden than in other populations. We have studied 239 cases of FAP from northern Sweden, their geographical distribution, differences in age of onset, and estimated prevalence and incidence rates. Cases and families concentrate mainly in two areas, around the towns of Skellefteå and Piteå. Mean age of onset was found to be later in the Piteå (58.8 +/- 10.8) than in the Skellefteå area (54.4 +/- 13.5). Unusually high figures were found for prevalence rates (91 x 10(-5) and 104 x 10(-5), respectively) in 1985. Mean yearly incidences were 3.1 x 10(-5) and 4.4 x 10(-5), respectively, over the period 1985-1989.

Familial amyloidotic polyneuropathy in Sweden: a pedigree analysis

Extended genealogical studies were performed on the heredity patterns in Swedish patients with familial amyloidotic polyneuropathy (FAP) using Swedish historical archives. The population studied included 239 patients: 109 patients were linked to five large pedigrees and 80 patients belonged to 30 smaller pedigrees or nuclear families. In the remaining 50 cases, no genealogical links were found. Differences in mean ages of onset between the different pedigrees were found, although a considerable variation within the pedigrees was also present. There was a tendency for later ages of onset among older generations than younger ones: descendants of affected mothers seem to be more prone to anticipation in age of onset than descendants of affected fathers. Furthermore, there seems to be a tendency for earlier ages of onset among patients with a carrier mother than a carrier father. Some extended pedigrees, from the Skellefteå and Piteå areas, are presented in detail. The former go back into the middle of the 17th century. One important conclusion is that the mutational event may have occurred in late mediaeval times.

The x-ray crystal structure refinements of normal human transthyretin and the amyloidogenic Val-30-->Met variant to 1.7-A resolution

The x-ray crystal structures of normal human transthyretin (prealbumin) and the amyloidogenic Val-30-Met variant have been refined at 1.7-A resolution to R-values of 0.168 and 0.179, respectively, for 19,882 and 20,362 reflections (Fobs > 2.0 sigma). Standard deviations for stereochemical parameters are 0.018 and 0.022 A for bond distances, 0.030 and 0.038 A for angle distances, and 0.035 and 0.070 A for planar 1-4 distances. The newly refined normal structure shows improvement over the original structure of Blake and Swan (Blake, C. C. F., and Swan, I. D. A. (1971) J. Mol. Biol. 61, 217-224) in stereochemistry and in the conformation of the loop regions. Residues Arg-103, Thr-123, Asn-124, and Pro-125 have now been resolved, and residues 1-9 and 126-127 have been modeled with the aid of simulated annealing refinement. The functional form of transthyretin is a tetramer, having a cylindrical cavity which will bind thyroxine and an exterior binding site for the complex of retinol with retinol-binding protein. The monomer is a beta barrel flattened to become more like a sandwich with residue 30 in the interior. The methionyl for valyl substitution forces the beta sheets of the monomer as much as 1 A apart, resulting in a distortion of the thyroxine-binding cavity, in agreement with the independent observations that the Met-30 variant has low affinity for thyroxine.

Modifications of transthyretin in amyloid fibrils: analysis of amyloid from homozygous and heterozygous individuals with the Met30 mutation

The finding of individuals homozygous for FAP I (familial amyloidotic polyneuropathy, transthyretin TTRMet30) with amyloid deposits in the vitreous body, gave us access to a unique material lacking wild type transthyretin and contaminating proteins. Amyloid TTR is modified in several ways. Besides the full-length protein and its dimer form, two smaller bands were identified by SDS-PAGE and protein sequencing. One corresponded to a peptide starting at amino acid Thr49, the other was a mixture of two peptides starting at positions 1 and 3 in a 3:1 ratio. Upon reduction the amount of the TTR dimer decreased, the monomer amount increased, and the resulting monomers became available for carboxymethylation. Moreover, the mobility of the small band, which includes Cys10, increased upon reduction. This cysteine seemed to be involved in an interchain disulfide bridge both between intact TTR molecules and between small fragments. The same pattern was found in heterozygous fibril material although smaller amounts of the truncated peptides were found. Fibrils were formed both from normal and mutated TTR in heterozygotes. The significance of our results for amyloid formation is discussed.

Alteration in molecular structure which results in disease: the Met-30 variant of human plasma transthyretin

The structure of a variant transthyretin has been determined by X-ray crystallography at 2.3 A resolution in order to investigate those changes which lead to amyloid formation. This variant transthyretin, in which the internal valyl residue at position 30 is replaced by methionyl, is associated with the most common form of familial amyloidotic polyneuropathy (FAP). Comparison to the known structure of the normal transthyretin tetramer shows that the bulkier methionine residue 30 which lies between the nearly orthogonal beta sheets of the dimer, results in the sheets being displaced an average of 0.4 A. The internal structure of the sheets and of the monomer-monomer interface is maintained. Such global changes may affect the metabolic properties and the tendency towards polymerization of the mutant protein. These findings may form a basis for understanding other amyloid-deposition diseases.

Vitreous involvement in familial amyloidotic neuropathy: a genealogical and genetic study

Extended genealogical studies stretching back to the 17th century were performed concerning the heredity patterns of vitreous involvement in Swedish patients with familial amyloidotic polyneuropathy (FAP). FAP is an autosomal dominant inherited disorder, characterized by extracellular deposition of amyloid and a clinical syndrome of peripheral and autonomic neuropathy. In addition, some patients show typical vitreous opacities. All patients had their origin in a restricted geographical area. Some main patterns arose from this study: 1) Patients who had vitreous opacities as the first symptom of FAP seem to form a separate group, with a distinct age of onset distribution; 2) The familial occurrence of vitreous opacities raises the possibility that other familial factors modify the expression of the FAP gene; 3) The mean age of onset for vitreous opacities is lower for homozygous than for heterozygous patients.

Vitreous amyloidosis associated with homozygosity for the transthyretin methionine-30 gene

Familial amyloidotic polyneuropathy is an autosomal dominant inherited disorder. Biochemical studies have revealed that the amyloid protein in familial amyloidotic polyneuropathy of Japanese, Swedish, and Portuguese origin mainly consists of a variant transthyretin with one amino acid substitution of methionine for valine at position 30, termed TTR met-30. In five Swedish patients with familial amyloidotic polyneuropathy we diagnosed homozygosity for the TTR met-30 gene using restriction fragment length polymorphism analysis. The homozygous individuals did not show more severe systemic symptoms or earlier onset than heterozygotes for the TTR met-30 gene. The only clinical difference was the presence of vitreous opacities in all homozygous patients.