Highly variable hearing loss due to POU4F3 (c.37del) is revealed by longitudinal, frequency specific analyses

Genotype-phenotype correlations add value to the management of families with hereditary hearing loss (HL), where age-related typical audiograms (ARTAs) are generated from cross-sectional regression equations and used to predict the audiogram phenotype across the lifespan. A seven-generation kindred with autosomal dominant sensorineural HL (ADSNHL) was recruited and a novel pathogenic variant in POU4F3 (c.37del) was identified by combining linkage analysis with whole exome sequencing (WES). POU4F3 is noted for large intrafamilial variation including the age of onset of HL, audiogram configuration and presence of vestibular impairment. Sequential audiograms and longitudinal analyses reveal highly variable audiogram features among POU4F3 (c.37del) carriers, limiting the utility of ARTAs for clinical prognosis and management of HL. Furthermore, a comparison of ARTAs against three previously published families (1 Israeli Jewish, 2 Dutch) reveals significant interfamilial differences, with earlier onset and slower deterioration. This is the first published report of a North American family with ADSNHL due to POU4F3, the first report of the pathogenic c.37del variant, and the first study to conduct longitudinal analysis, extending the phenotypic spectrum of DFNA15.

Autosomal dominant non-syndromic hearing loss maps to DFNA33 (13q34) and co-segregates with splice and frameshift variants in ATP11A, a phospholipid flippase gene

Sequencing exomes/genomes have been successful for identifying recessive genes; however, discovery of dominant genes including deafness genes (DFNA) remains challenging. We report a new DFNA gene, ATP11A, in a Newfoundland family with a variable form of bilateral sensorineural hearing loss (SNHL). Genome-wide SNP genotyping linked SNHL to DFNA33 (LOD = 4.77), a locus on 13q34 previously mapped in a German family with variable SNHL. Whole-genome sequencing identified 51 unremarkable positional variants on 13q34. Continuous clinical ascertainment identified several key recombination events and reduced the disease interval to 769 kb, excluding all but one variant. ATP11A (NC_000013.11: chr13:113534963G>A) is a novel variant predicted to be a cryptic donor splice site. RNA studies verified in silico predictions, revealing the retention of 153 bp of intron in the 3' UTR of several ATP11A isoforms. Two unresolved families from Israel were subsequently identified with a similar, variable form of SNHL and a novel duplication (NM_032189.3:c.3322_3327+2dupGTCCAGGT) in exon 28 of ATP11A extended exon 28 by 8 bp, leading to a frameshift and premature stop codon (p.Asn1110Valfs43Ter). ATP11A is a type of P4-ATPase that transports (flip) phospholipids from the outer to inner leaflet of cell membranes to maintain asymmetry. Haploinsufficiency of ATP11A, the phospholipid flippase that specially transports phosphatidylserine (PS) and phosphatidylethanolamine (PE), could leave cells with PS/PE at the extracellular side vulnerable to phagocytic degradation. Given that surface PS can be pharmaceutically targeted, hearing loss due to ATP11A could potentially be treated. It is also likely that ATP11A is the gene underlying DFNA33.

"Something is just not right with my hearing": early experiences of adults living with hearing loss

OBJECTIVE

To understand the psychosocial process of how adults experience hearing loss; specifically, their readiness to accept that they may have hearing loss, and the challenges and coping strategies associated with it.

DESIGN

A grounded theory methodology guided the research. A patient-orientated research approach informed the study. Thirty-nine individual interviews and six focus groups were completed.

STUDY SAMPLE

Participants included 68 individuals aged 50 years and older with self-reported hearing loss living in Newfoundland and Labrador.

RESULTS

The theoretical construct, 'Realising that something is just not quite right with my hearing' captured individuals' experiences as they gradually awakened to the fact that they had hearing loss. Three categories describe the process: (1) Rationalising suspicions, (2) Managing the invisible and (3) Reaching a turning point.

CONCLUSIONS

Many individuals do not recognise hearing loss in its early stages, although they may be already experiencing its negative effects. It is important to identify motivators to engage individuals as early as possible in their hearing health. Taking a proactive approach to hearing health can help mitigate the potential negative outcomes of hearing loss.

Psychological Distress and Quality of Life in Participants Undergoing Genetic Testing for Arrhythmogenic Right Ventricular Cardiomyopathy Caused by TMEM43 p.S358L: Is It Time to Offer Population-Based Genetic Screening?

PURPOSE

We have identified 27 families in Newfoundland and Labrador (NL) with the founder variant TMEM43 p.S358L responsible for 1 form of arrhythmogenic right ventricular cardiomyopathy. Current screening guidelines rely solely on cascade genetic screening, which may result in unrecognized, high-risk carriers who would benefit from preemptive implantable cardioverter-defibrillator therapy. This pilot study explored the acceptability among subjects to TMEM43 p.S358L population-based genetic screening (PBGS) in this Canadian province.

METHODS

A prospective cohort study assessed attitudes, psychological distress, and health-related quality of life (QOL) in unselected individuals who underwent genetic screening for the TMEM43 p.S358L variant. Participants (n = 73) were recruited via advertisements and completed 2 surveys at baseline, 6 months, and 1 year which measured health-related QOL (SF-36v2) and psychological distress (Impact of Events Scale).

RESULTS

No variant-positive carriers were identified. Of those screened through a telephone questionnaire, >95% felt positive about population-genetic screening for TMEM43 p.S358L, though 68% reported some degree of anxiety after seeing the advertisement. There were no significant changes in health-related QOL or psychological distress scores over the study period.

CONCLUSION

Despite some initial anxiety, we show support for PBGS among research subjects who screened negative for the TMEM43 p.S358L variant in NL. These findings have implications for future PBGS programs in the province.

Exercise and arrhythmic risk in TMEM43 p.S358L arrhythmogenic right ventricular cardiomyopathy

BACKGROUND

High-level exercise has been associated with a malignant phenotype in desmosomal and genotype-negative forms of arrhythmogenic right ventricular cardiomyopathy (ARVC). This is the first study to examine this issue with ARVC secondary to the TMEM43 p.S358L mutation.

OBJECTIVE

The purpose of this study was to evaluate the impact of exercise on arrhythmic risk and cardiac death in TMEM43 p.S358L ARVC.

METHODS

Individuals with the TMEM43 p.S358L mutation enrolled in a prospective registry who had received a primary prevention implantable cardioverter-defibrillator (ICD) were invited to complete the modified Paffenbarger Physical Activity Questionnaire to assess their physical activity in the year before their ICD implantation. Time-to-event analyses using unadjusted and adjusted Cox proportional hazards models evaluated associations between physical activity and first appropriate ICD discharge secondary to malignant ventricular arrhythmia or cardiac death.

RESULTS

In 80 subjects with the TMEM43 p.S358L mutation, exercise ≥9.0 metabolic equivalent of task (MET)-hours/day (high level) in the year before ICD implantation was associated with an adjusted 9.1-fold increased hazard of first appropriate ICD discharge (there were no deaths) relative to physical activity <9.0 MET-hours/day (moderate level) (95% confidence interval [CI] 3.3-24.6 MET-hours/day; P < .001). The median age from birth to first appropriate ICD discharge was 58.5 years (95% CI 56.5-60.5 years) vs 35.8 years (95% CI 28.2-43.4 years) (P < .001) in subjects in moderate- and high-level exercise groups, respectively.

CONCLUSION

Exercise ≥9.0 MET-hours/day is associated with an increased risk of malignant ventricular arrhythmias in the TMEM43 p.S358L subtype of ARVC. Extrapolating these data, we suggest molecular testing be offered in early childhood to inform exercise choices reflective of the genotype.

A dominant RAD51C pathogenic splicing variant predisposes to breast and ovarian cancer in the Newfoundland population due to founder effect

Background

RAD51C is important in DNA repair and individuals with pathogenic RAD51C variants have increased risk of hereditary breast and ovarian cancer syndrome (HBOC), an autosomal dominant genetic predisposition to early onset breast and/or ovarian cancer.

Methods

Five female HBOC probands sequenced negative for moderate‐ and high‐risk genes but shared a recurrent variant of uncertain significance in RAD51C (NM_058216.3: c.571 + 4A > G). Participant recruitment was followed by haplotype and case/control analyses, RNA splicing analysis, gene and protein expression assays, and Sanger sequencing of tumors.

Results

The RAD51C c.571 + 4A > G variant segregates with HBOC, with heterozygotes sharing a 5.07 Mbp haplotype. RAD51C c.571 + 4A > G is increased ~52‐fold in the Newfoundland population compared with the general Caucasian population and positive population controls share disease‐associated alleles, providing evidence of a founder effect. Splicing analysis confirmed in silico predictions that RAD51C c.571 + 4A > G causes exon 3 skipping, creating an immediate premature termination codon. Gene and protein expression were significantly reduced in a RAD51C c.571 + 4G > A heterozygote compared with a wild‐type relative. Sanger sequencing of tumors from two probands indicates loss‐of‐heterozygosity, suggesting loss of function.

Conclusion

The RAD51C c.571 + 4A > G variant affects mRNA splicing and should be re‐classified as pathogenic according to American College of Medical Genetics and Genomics guidelines.

Novel Usher syndrome pathogenic variants identified in cases with hearing and vision loss

Background

Usher syndrome, the most common form of inherited deaf-blindness, is unlike many other forms of syndromic hereditary hearing loss in that the extra aural clinical manifestations are also detrimental to communication. Usher syndrome patients with early onset deafness also experience vision loss due to progressive retinitis pigmentosa that can lead to legal blindness in their third or fourth decade.

Methods

Using a multi-omic approach, we identified three novel pathogenic variants in two Usher syndrome genes (USH2A and ADGRV1) in cases initially referred for isolated vision or hearing loss.

Results

In a multiplex hearing loss family, two affected sisters, the product of a second cousin union, are homozygous for a novel nonsense pathogenic variant in ADGRV1 (c.17062C > T, p.Arg5688*), predicted to create a premature stop codon near the N-terminus of ADGRV1. Ophthalmological examination of the sisters confirmed typical retinitis pigmentosa and prompted a corrected Usher syndrome diagnosis. In an unrelated clinical case, a child with hearing loss tested positive for two novel USH2A splicing variants (c.5777-1G > A, p. Glu1926_Ala1952del and c.10388-2A > G, p.Asp3463Alafs*6) and RNA studies confirmed that both pathogenic variants cause splicing errors. Interestingly, these same USH2A variants are also identified in another family with vision loss where subsequent clinical follow-up confirmed pre-existing hearing loss since early childhood, eventually resulting in a reassigned diagnosis of Usher syndrome.

Conclusion

These findings provide empirical evidence to increase Usher syndrome surveillance of at-risk children. Given that novel antisense oligonucleotide therapies have been shown to rescue retinal degeneration caused by USH2A splicing pathogenic variants, these solved USH2A patients may now be eligible to be enrolled in therapeutic trials.

“There are days I wish it wasn’t there, and there’s days I realize I’m lucky”: A qualitative study of psychological sequelae to the implantable cardioverter defibrillator as a treatment for the prevention of sudden cardiac death in arrhythmogenic right ventricular cardiomyopathy

Objectives

Arrhythmogenic right ventricular cardiomyopathy caused by a TMEM43 p.S358L mutation is a fully penetrant autosomal dominant cause of sudden cardiac death where prophylactic implantable cardioverter defibrillator therapy significantly reduces mortality by returning lethal cardiac rhythms to normal. This qualitative study assessed the psychological ramifications of the implantable cardioverter defibrillator on recipients, their spouses and their mutation negative siblings.

Design

Qualitative interview study.

Participants

Twenty-one individuals (nine mutation positive, eight mutation negative and four spouses) from 15 families completed semi-structured interviews.

Results

No theoretical assumptions about the data were made: inductive sub-coding was accomplished with the constant comparison method and cohesive themes across all respondent interviews were determined. All interviewees had a family history of sudden cardiac death and appropriate implantable cardioverter defibrillator therapy in themselves or family members. Average length of time with an implantable cardioverter defibrillator was 10 years. Major themes included: (1) acceptance and gratitude, (2) grudging acceptance, (3) psychological effects (on emotional and psychological well-being; functioning of the broader family unit; and relationships), and (4) practical concerns (on clothes, travel, loss of driving licence and the effects of an implantable cardioverter defibrillator discharge). These affected all family members, regardless of mutation status.

Conclusions

Despite the survival advantage of implantable cardioverter defibrillator therapy, the intervention carries psychological and practical burdens for family members from kindreds manifesting p.S358L TMEM43 ARVC that does not appear to dissipate with time. A move towards integrating psychology services with the cardiac genetics clinic for the extended family may provide benefit.

A common variant in CLDN14 causes precipitous, prelingual sensorineural hearing loss in multiple families due to founder effect

Genetic isolates provide unprecedented opportunities to identify pathogenic mutations and explore the full natural history of clinically heterogeneous phenotypes such as hearing loss. We noticed a unique audioprofile, characterized by prelingual and rapid deterioration of hearing thresholds at frequencies >0.5 kHz in several adults from unrelated families from the island population of Newfoundland. Targeted serial Sanger sequencing of probands for deafness alleles (n = 23) that we previously identified in this founder population was negative. Whole exome sequencing in four members of the largest family (R2010) identified a CLDN14 (DFNB29) variant [c.488C>T; p. (Ala163Val)], likely pathogenic, sensorineural hearing loss, autosomal recessive. Although not associated with deafness or disease, CLDN14 p.(Ala163Val) has been previously reported as a variant of uncertain significance (VUS). Targeted sequencing of 169 deafness probands identified one homozygote and one heterozygous carrier. Genealogical studies, cascade sequencing and haplotype analysis across four unrelated families showed all subjects with the unique audioprofile (n = 12) were also homozygous for p.(Ala163Val) and shared a 1.4 Mb DFNB29-associated haplotype on chromosome 21. Most significantly, sequencing 175 population controls revealed 1% of the population are heterozygous for CLDN14 p.(Ala163Val), consistent with a major founder effect in Newfoundland. The youngest CLDN14 [c.488C>T; p.(Ala163Val)] homozygote passed newborn screening and had normal hearing thresholds up to 3 years of age, which then deteriorated to a precipitous loss >1 kHz during the first decade. Our study suggests that genetic testing may be necessary to identify at-risk children in time to prevent speech, language and developmental delay.

Long-Term Clinical Outcome of Arrhythmogenic Right Ventricular Cardiomyopathy in Individuals With a p.S358L Mutation in TMEM43 Following Implantable Cardioverter Defibrillator Therapy

Background—

We previously showed a survival benefit of the implantable cardioverter defibrillator (ICD) in males with arrhythmogenic right ventricular cardiomyopathy caused by a p.S358L mutation in TMEM43 . We present long-term data (median follow-up 8.5years) after ICD for primary (PP) and secondary prophylaxis in males and females, determine whether ICD discharges for ventricular tachycardia/ventricular fibrillation were equivalent to an aborted death, and assess relevant clinical predictors.

Methods and Results—

We studied 24 multiplex families segregating an autosomal dominant p.S358L mutation in TMEM43 . We compared survival in 148 mutation carriers with an ICD to 148 controls matched for age, sex, disease status, and family. Of 80 male mutation carriers with ICDs (median age at implantation 31 years), 61 (76%) were for PP; of 68 females (median age at implantation 43 years), 66 (97%) were for PP. In males, irrespective of indication, survival was better in the ICD groups compared with control groups (relative risk 9.3 [95% confidence interval 3.3–26] for PP and 9.7 [95% confidence interval 3.2–29.6] for secondary prophylaxis). For PP females, the relative risk was 3.6 (95% confidence interval 1.3–9.5). ICD discharge-free survival for ventricular tachycardia/ventricular fibrillation ≥240 beats per minute was equivalent to the control survival rate. Ectopy (≥1000 premature ventricular complexes/24 hours) was the only independent clinical predictor of ICD discharge in males, and no predictor was identified in females.

Conclusions—

ICD therapy is indicated for PP in postpubertal males and in females ≥30 years with the p.S358L TMEM43 mutation. ICD termination of rapid ventricular tachycardia/ventricular fibrillation can reasonably be considered an aborted death.

Characteristics of Fatal Agricultural Injuries by Production Type

Although agriculture is recognized as a hazardous industry, it is unclear how fatal agricultural injuries differ by production type. The purpose of this study was to characterize fatal occupational injuries in agriculture, comparing crop and animal production, and determine which risk factors are specifically associated with each production type. A cross-sectional study was conducted among crop and animal pro ducers using data from the Census of Fatal Occupational Injuries in the Midwest region from 2005 to 2012. Rates offatal injury by production type were estimated. The frequency of fatal injury in each production type was also reported by demographic and injury characteristics. Finally, a logistic regression was performed to determine whether age, gender, injury timing, or injury event/exposure type were associated with crop or animal production. A total of 1,858 fatal agriculture-related injuries were identified, with 1,341 in crop production and 517 in animal production. The estimated rate of fatal injury was higher in crop production than in animal production (15.9 vs. 10.8 per 100,000 workers). Fatal injuries among young and elderly agricultural workers were significantly associated with crop production compared to animal production. Animal assaults, falls, and exposure to harmful substances or environments were significantly associated with animal production. Fatal agricultural injury is more common in crop production. However, the characteristics and risk factors of fatal injuries differ by production type. Intervention strategies may be guided by considering the production-specflc risk factors.

X-linked hearing loss: two gene mutation examples provide generalizable implications for clinical care

PURPOSE

To describe the inheritance patterns and auditory phenotype features of 3 Canadian families with mutations in 2 X-linked "deafness" genes (DFNX).

METHOD

Audiological, medical, and family histories were collected and family members interviewed to compare hearing thresholds and case histories between cases with mutations in SMPX versus POU3F4.

RESULTS

The family pedigrees reveal characteristic X-linked inheritance patterns. Phenotypic features associated with the SMPX (DFNX4) mutation include early onset in males with rapid progression from mild and flat to sloping sensorineural loss, with highly variable onset and hearing loss severity in females. In contrast, phenotypic features associated with the POU3F4 (DFNX2) mutation are characterized by an early onset, mixed hearing loss with fluctuation in males, and a normal hearing phenotype reported for females.

CONCLUSIONS

The study shows how this unique inheritance pattern and both gender and mutation-specific phenotype variations can alert audiologists to the presence of X-linked genetic etiologies in their clinical practice. By incorporating this knowledge into clinical decision making, audiologists can facilitate the early identification of X-linked hearing loss and contribute to the effective team management of affected families.

Identification of a novel in-frame deletion in KCNQ4 (DFNA2A) and evidence of multiple phenocopies of unknown origin in a family with ADSNHL

Autosomal dominant sensorineural hearing loss (ADSNHL) is extremely genetically heterogeneous, making it difficult to molecularly diagnose. We identified a multiplex (n=28 affected) family from the genetic isolate of Newfoundland, Canada with variable SNHL and used a targeted sequencing approach based on population-specific alleles in WFS1, TMPRSS3 and PCDH15; recurrent mutations in GJB2 and GJB6; and frequently mutated exons of KCNQ4, COCH and TECTA. We identified a novel, in-frame deletion (c.806_808delCCT: p.S269del) in the voltage-gated potassium channel KCNQ4 (DFNA2), which in silico modeling predicts to disrupt multimerization of KCNQ4 subunits. Surprisingly, 10/23 deaf relatives are non-carriers of p.S269del. Further molecular characterization of the DFNA2 locus in deletion carriers ruled out the possibility of a pathogenic mutation other than p.S269del at the DFNA2A/B locus and linkage analysis showed significant linkage to DFNA2 (maximum LOD=3.3). Further support of genetic heterogeneity in family 2071 was revealed by comparisons of audio profiles between p.S269del carriers and non-carriers suggesting additional and as yet unknown etiologies. We discuss the serious implications that genetic heterogeneity, in this case observed within a single family, has on molecular diagnostics and genetic counseling.

Molecular genetics of achromatopsia in Newfoundland reveal genetic heterogeneity, founder effects and the first cases of Jalili syndrome in North America

Achromatopsia (ACHM) is a severe retinal disorder characterized by an inability to distinguish colors, impaired visual acuity, photophobia and nystagmus. This rare autosomal recessive disorder of the cone photoreceptors is best known for its increased frequency due to founder effect in the Pingelapese population of the Pacific islands. Sixteen patients from Newfoundland, Canada were sequenced for mutations in the four known achromatopsia genes CNGA3, CNGB3, GNAT2, and PDE6C. The majority (n = 12) of patients were either homozygotes or compound heterozygotes for known achromatopsia alleles, two in CNGB3 (p.T383fsX and p.T296YfsX9) and three in CNGA3 (p.R283Q, p.R427C and p.L527R). Haplotype reconstruction showed that recurrent mutations p.T383fsX and p.L527R were due to a founder effect. Aggregate data from exome sequencing, segregation analysis and archived medical records support a rediagnosis of Jalili syndrome in affected siblings (n = 4) from Family 0094, which to our knowledge is the first family identified with Jalili Syndrome in North America.

A novel deletion in SMPX causes a rare form of X-linked progressive hearing loss in two families due to a founder effect

X-linked hearing loss is the rarest form of genetic hearing loss contributing to <1% of cases. We identified a multiplex family from Newfoundland (Family 2024) segregating X-linked hearing loss. Haplotyping of the X chromosome and sequencing of positional candidate genes revealed a novel point deletion (c.99delC) in SMPX which encodes a small muscle protein responsible for reducing mechanical stress during muscle contraction. This novel deletion causes a frameshift and a premature stop codon (p.Arg34GlufsX47). We successfully sequenced both SMPX wild-type and mutant alleles from cDNA of a lymphoblastoid cell line, suggesting that the mutant allele may not be degraded via nonsense-mediated mRNA decay. To investigate the role of SMPX in other subpopulations, we fully sequenced SMPX in 229 Canadian probands with hearing loss and identified a second Newfoundland Family (2196) with the same mutation, and a shared haplotype on the X chromosome, suggesting a common ancestor.

Variable neurologic phenotype in a GEFS+ family with a novel mutation in SCN1A

PURPOSE

To describe the spectrum of clinical disease in a mutliplex family with an autosomal dominant form of generalized epilepsy with febrile seizures plus (GEFS+) and determine its genetic etiology.

METHODS

Medical and family history was obtained on 11 clinically affected individuals and their relatives across three generations through medical chart review and home visits. A candidate gene approach including haplotype analysis and direct sequencing was used.

RESULTS

An epilepsy-associated haplotype was identified on 2q24. Direct sequencing of the entire SCN1A gene identified seven sequence variants. However, only one of these, c.1162 T>C, was not found in population controls. This transition in exon 8 of SCN1A predicts a substitution (Y388H) of a highly conserved tyrosine residue in the loop between transmembrane segments S5 and S6 of the sodium channel protein (Na(v)1.1). Clinical features in mutation carriers of this novel missense mutation were highly variable, ranging from febrile seizures to severe refractory epilepsy.

CONCLUSION

A novel missense mutation in the pore-forming region of the sodium channel gene SCN1A causes GEFS+ with a variable phenotype that includes mood and anxiety disorders, as well as ataxia, expanding the GEFS+ spectrum to include neuropsychiatric disease.

Autosomal recessive Bardet-Biedl syndrome: first-degree relatives have no predisposition to metabolic and renal disorders

Bardet-Biedl Syndrome (BBS) is an autosomal recessive, multisystem, genetically heterogeneous, ciliopathic condition caused by mutations in multiple genes. Here we sought to determine if inheritance of a single BBS mutation increased the risks of frequent disorders of this syndrome such as obesity, hypertension, and diabetes. Various metabolic and renal diseases in a cohort of 46 patients with BBS, prospectively followed for up to 28 years, were compared to recent assessments of these factors in 96 relatives with a heterozygote mutation (carriers) and 37 relatives without a contributing mutation (non-carriers). Ten mutations in 6 genes causing this syndrome were identified in 21 families from whom DNA was obtained. The body mass index or the incidences of hypertension, diabetes, or stage 3 chronic kidney diseases were found to be similar between carriers and non-carriers but were all significantly less than those of family members with BBS. Similarly, the median age of onset of hypertension or diagnosis of stage 3 kidney disease, or the diagnosis of diabetes by age 70 were all significantly lower in those with BBS than in gene carriers or non-carriers. While our study shows that metabolic and renal events occurred frequently and at an early age in BBS, the heterozygous inheritance of any of the 10 described BBS mutations did not predispose family members to obesity, diabetes, hypertension, or renal impairment.

Profound, prelingual nonsyndromic deafness maps to chromosome 10q21 and is caused by a novel missense mutation in the Usher syndrome type IF gene PCDH15

We studied a consanguineous family (Family A) from the island of Newfoundland with an autosomal recessive form of prelingual, profound, nonsyndromic sensorineural hearing loss. A genome-wide scan mapped the deafness trait to 10q21-22 (max LOD score of 4.0; D10S196) and fine mapping revealed a 16 Mb ancestral haplotype in deaf relatives. The PCDH15 gene was mapped within the critical region and was an interesting candidate because truncating mutations cause Usher syndrome type IF (USH1F) and two missense mutations have been previously associated with isolated deafness (DFNB23). Sequencing of the PCDH15 gene revealed 33 sequencing variants. Three of these variants were homozygous exclusively in deaf siblings but only one of them was not seen in ethnically matched controls. This novel c.1583 T>A transversion predicts an amino-acid substitution of a valine with an aspartic acid at codon 528 (V528D). Like the two DFNB23 mutations, the V528D mutation in Family A occurs in a highly conserved extracellular cadherin (EC) domain of PCDH15 and is predicted to be more deleterious than the previously identified DFNB23 missense mutations (R134G and G262D). Physical assessment, vestibular and visual function testing in deaf adults ruled out syndromic deafness because of Usher syndrome. This study validates the DFNB23 designation and supports the hypothesis that missense mutations in conserved motifs of PCDH15 cause nonsyndromic hearing loss. This emerging genotype-phenotype correlation in USH1F is similar to that in several other USH1 genes and cautions against a prognosis of a dual sensory loss in deaf children found to be homozygous for hypomorphic mutations at the USH1F locus.

Arrhythmogenic right ventricular cardiomyopathy type 5 is a fully penetrant, lethal arrhythmic disorder caused by a missense mutation in the TMEM43 gene

Autosomal-dominant arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) causes sudden cardiac death and is characterized by clinical and genetic heterogeneity. Fifteen unrelated ARVC families with a disease-associated haplotype on chromosome 3p (ARVD5) were ascertained from a genetically isolated population. Identification of key recombination events reduced the disease region to a 2.36 Mb interval containing 20 annotated genes. Bidirectional resequencing showed one rare variant in transmembrane protein 43 (TMEM43 1073C-->T, S358L), was carried on all recombinant ARVD5 ancestral haplotypes from affected subjects and not found in population controls. The mutation occurs in a highly conserved transmembrane domain of TMEM43 and is predicted to be deleterious. Clinical outcomes in 257 affected and 151 unaffected subjects were compared, and penetrance was determined. We concluded that ARVC at locus ARVD5 is a lethal, fully penetrant, sex-influenced morbid disorder. Median life expectancy was 41 years in affected males compared to 71 years in affected females (relative risk 6.8, 95% CI 1.3-10.9). Heart failure was a late manifestation in survivors. Although little is known about the function of the TMEM43 gene, it contains a response element for PPAR gamma (an adipogenic transcription factor), which may explain the fibrofatty replacement of the myocardium, a characteristic pathological finding in ARVC.

The noncoding RNA taurine upregulated gene 1 is required for differentiation of the murine retina

BACKGROUND

With the advent of genome-wide analyses, it is becoming evident that a large number of noncoding RNAs (ncRNAs) are expressed in vertebrates. However, of the thousands of ncRNAs identified, the functions of relatively few have been established.

RESULTS

In a screen for genes upregulated by taurine in developing retinal cells, we identified a gene that appears to be a ncRNA. Taurine Upregulated Gene 1 (TUG1) is a spliced, polyadenylated RNA that does not encode any open reading frame greater than 82 amino acids in its full-length, 6.7 kilobase (kb) RNA sequence. Analyses of Northern blots and in situ hybridization revealed that TUG1 is expressed in the developing retina and brain, as well as in adult tissues. In the newborn retina, knockdown of TUG1 with RNA interference (RNAi) resulted in malformed or nonexistent outer segments of transfected photoreceptors. Immunofluorescent staining and microarray analyses suggested that this loss of proper photoreceptor differentiation is a result of the disregulation of photoreceptor gene expression.

CONCLUSIONS

A function for a newly identified ncRNA, TUG1, has been established. TUG1 is necessary for the proper formation of photoreceptors in the developing rodent retina.

Familial variable expression of dilated cardiomyopathy in Alström syndrome: A report of four sibs

Alström syndrome is an autosomal recessive disorder comprised of progressive vision loss (nystagmus, photophobia, and pigmentary retinopathy), progressive sensorineural hearing loss, morbid obesity, male hypogonadism, insulin resistant diabetes, renal failure, and dilated cardiomyopathy. We report on four sibs with Alström syndrome with intra-familial variability in onset, severity, and spectrum of manifestations; the most serious manifestation being dilated cardiomyopathy. This report emphasizes the difficulty of recognizing this constellation of symptoms as Alström syndrome at an early age, the seriousness of cardiac involvement, and the intra-familial variability of phenotypic expression.

Characterization of a new full length TMPRSS3 isoform and identification of mutant alleles responsible for nonsyndromic recessive deafness in Newfoundland and Pakistan

Background

Mutant alleles of TMPRSS3 are associated with nonsyndromic recessive deafness (DFNB8/B10). TMPRSS3 encodes a predicted secreted serine protease, although the deduced amino acid sequence has no signal peptide. In this study, we searched for mutant alleles of TMPRSS3 in families from Pakistan and Newfoundland with recessive deafness co-segregating with DFNB8/B10 linked haplotypes and also more thoroughly characterized the genomic structure of TMPRSS3.

Methods

We enrolled families segregating recessive hearing loss from Pakistan and Newfoundland. Microsatellite markers flanking the TMPRSS3 locus were used for linkage analysis. DNA samples from participating individuals were sequenced for TMPRSS3. The structure of TMPRSS3 was characterized bioinformatically and experimentally by sequencing novel cDNA clones of TMPRSS3.

Results

We identified mutations in TMPRSS3 in four Pakistani families with recessive, nonsyndromic congenital deafness. We also identified two recessive mutations, one of which is novel, of TMPRSS3 segregating in a six-generation extended family from Newfoundland. The spectrum of TMPRSS3 mutations is reviewed in the context of a genotype-phenotype correlation. Our study also revealed a longer isoform of TMPRSS3 with a hitherto unidentified exon encoding a signal peptide, which is expressed in several tissues.

Conclusion

Mutations of TMPRSS3 contribute to hearing loss in many communities worldwide and account for 1.8% (8 of 449) of Pakistani families segregating congenital deafness as an autosomal recessive trait. The newly identified TMPRSS3 isoform e will be helpful in the functional characterization of the full length protein.

An analysis of the gene expression program of mammalian neural progenitor cells

A diverse range of neural cell types is generated from a pool of dividing stem and progenitor cells in an orderly manner during development. Little is known of the molecular and cellular biology underpinning the intrinsic control of this process. We have used a nonbiased method to purify populations of neural progenitor cells from the murine CNS to characterize the gene expression program of mammalian retinal progenitor cells. Analysis of these data led to the identification of a core set of >800 transcripts enriched in retinal progenitor cells compared to both their immediate postmitotic progeny and to differentiated neurons. This core set was found to be shared by progenitors in other regions of the developing CNS, with important regional differences in key functional families. In addition to providing an expression fingerprint of this cell type, this set highlights several key aspects of progenitor biology.

Mutational spectrum of the WFS1 gene in Wolfram syndrome, nonsyndromic hearing impairment, diabetes mellitus, and psychiatric disease

WFS1 is a novel gene and encodes an 890 amino-acid glycoprotein (wolframin), predominantly localized in the endoplasmic reticulum. Mutations in WFS1 underlie autosomal recessive Wolfram syndrome and autosomal dominant low frequency sensorineural hearing impairment (LFSNHI) DFNA6/14. In addition, several WFS1 sequence variants have been shown to be significantly associated with diabetes mellitus and this gene has also been implicated in psychiatric diseases. Wolfram syndrome is highly variable in its clinical manifestations, which include diabetes insipidus, diabetes mellitus, optic atrophy, and deafness. Wolfram syndrome mutations are spread over the entire coding region, and are typically inactivating, suggesting that a loss of function causes the disease phenotype. In contrast, only non-inactivating mutations have been found in DFNA6/14 families, and these mutations are mainly located in the C-terminal protein domain. In this paper, we provide an overview of the currently known disease-causing and benign allele variants of WFS1 and propose a potential genotype-phenotype correlation for Wolfram syndrome and LFSNHI.

Retinal neovascular markers in retinopathy of prematurity: aetiological implications

AIM

(1) To determine if expression of the blood-tissue barrier associated glucose transporter GLUT1 is preserved by the neovasculature of retinopathy of prematurity (ROP), in contrast with the reported loss of GLUT1 expression in preretinal vessels of proliferative diabetic retinopathy. (2) To compare the vascular immunophenotype of ROP to juvenile haemangioma, another perinatal neovascular disorder that has recently been shown to express placental type vascular antigens, including GLUT1 and Lewis Y antigen.

METHODS

A retrospective case report was carried out. Immunoreactivities for GLUT1 and Lewis Y antigen were assessed in a human eye with stage 3 ROP and compared with those in a control (paediatric) eye. The presence or absence of endothelial GLUT1 and Lewis Y immunoreactivity was determined in preretinal and intraretinal vessels.

RESULTS

Immunoreactivity was positive for GLUT1 and negative for Lewis Y in the intraretinal and preretinal neovasculature of the ROP affected eye and in the normal retinal vessels of the control eye.

CONCLUSIONS

Retention of immunoreactivity for GLUT1 distinguishes ROP from proliferative diabetic retinopathy. Furthermore, absence of Lewis Y antigen co-expression distinguishes ROP from juvenile haemangioma, a perinatal form of GLUT1 positive neovascularisation that has recently been linked to placental vasculature.

Efficacy of inferior oblique anterior transposition placement grading for dissociated vertical deviation

OBJECTIVE

To determine if graded anterior placement of a transposed inferior oblique muscle is beneficial for treating variable amounts of dissociated vertical deviation (DVD).

DESIGN

Retrospective, consecutive, comparative case series.

PARTICIPANTS

Patients who underwent inferior oblique muscle anterior transposition (IOAT) for DVD at one institution between 1991 and 1999.

METHODS

Chart review. All patients had IOAT procedures of graded placement at 1, 2, or 3 mm anterior to the inferior rectus muscle insertion or standard placement at the level of the inferior rectus muscle insertion.

MAIN OUTCOME MEASURES

The effect of graded and standard placement was assessed by measuring the difference between preoperative and postoperative DVD and was defined as DVD correction. The success of surgery was judged by the residual DVD at long-term follow-up of 6 months or more. Excellent, fair, and poor outcomes were defined as residual DVD of 0 to 5 prism diopters (PD), 6 to 12 PD, and 13 or more PD, respectively.

RESULTS

Fifty-five patients (106 eyes) underwent IOAT for DVD. The comparison of DVD correction for the standard versus graded group yielded significance at long-term follow-up (P = 0.001). This result became nonsignificant after adjusting for preoperative DVD (P = 0.178). The power to detect a 5-PD difference between graded and standard placement was 90%. The surgical success was similar for patients receiving graded and standard IOAT. Patients with 0 to 15 PD of preoperative DVD fared better than those with more than 15 PD of preoperative DVD.

CONCLUSIONS

This study does not demonstrate increased correction of DVD with graded IOAT versus standard IOAT. We do not recommend placement of the inferior oblique muscle anterior to the inferior rectus muscle insertion. Inferior oblique muscle anterior transposition for DVD was clinically more effective for smaller amounts of DVD.

Non-syndromic progressive hearing loss DFNA38 is caused by heterozygous missense mutation in the Wolfram syndrome gene WFS1

Dominantly inherited progressive hearing loss DFNA38 is caused by heterozygosity for a novel mutation in WFS1, the gene for recessively inherited Wolfram syndrome. Wolfram syndrome is defined by juvenile diabetes mellitus and optic atrophy and may include progressive hearing loss and other neurological symptoms. Heterozygotes for other Wolfram syndrome mutations generally have normal hearing. Dominant deafness defined by DFNA38 is more severe than deafness of Wolfram syndrome patients and lacks any syndromic features. In a six-generation kindred from Newfoundland, Canada, WFS1 Ala716Thr (2146 G-->A) was shared by all deaf members of the family and was specific to deaf individuals. The causal relationship between this missense mutation and deafness was supported by two observations based on haplotype and mutation analysis of the kindred. First, a relative homozygous for the mutation was diagnosed at age 3 years with insulin-dependent diabetes mellitus, the central feature of Wolfram syndrome. Second, two relatives with normal hearing had an identical haplotype to that defining DFNA38, with the exception of the base pair at position 2146. Other rare variants of WFS1 co-inherited with deafness in the family could be excluded as disease-causing mutations on the basis of this hearing-associated haplotype. The possibility that 'mild' mutations in WFS1 might be a cause of non-syndromic deafness in the general population should be explored.

Further refinement of the MYP2 locus for autosomal dominant high myopia by linkage disequilibrium analysis

INTRODUCTION

High myopia (>-6.00 diopters) is a complex common disorder that predisposes individuals to retinal detachment, glaucoma, macular degeneration, and premature cataracts. A recent linkage analysis of seven families with autosomal dominant high myopia has identified one locus (MYP2) for high myopia on chromosome 18p11.31 (Young et al.: Am J Hum Genet 1998;63:109-119). Haplotype analysis revealed an initial interval of 7.6 centimorgans (cM).

METHODS

Transmission disequilibrium tests (TDT) with both the Statistical Analysis for Genetic Epidemiology (SAGE) 3.1 TDTEX and GENEHUNTER 2 (GH2) programs were performed using chromosome 18p marker alleles for this interval.

RESULTS

Using SAGE analysis, the following p values were obtained for markers in marker order in this region: D18S1146 (p = 0.227), D18S481 (p = 0.001), D18S63 (p = 0.062), D18S1138 (p = 0.0004), D18S52 (p = 1.79 x 10(-6)), and D18S62 (p = 0.141). GH2 TDT analysis revealed the following p values for the best allele for the markers: D18S1146 (p = 0.083), D18S481 (p = 0.108), D18S63 (p = 0.034), D18S1138 (p = 0.011), D18S52 (p = 0.007), and D18S62 (p = 0.479).

CONCLUSION

These data suggest that the gene for 18p11.31-linked high myopia is most proximal to marker D18S52, with a likely interval of 0.8 cM between markers D18S63 and D18S52. Due to the contraction of the interval size by TDT, these results provide a basis for focused positional cloning and candidate gene analysis at the MYP2 locus.

Organized sports for children and preadolescents

Participation in organized sports provides an opportunity for young people to increase their physical activity and develop physical and social skills. However, when the demands and expectations of organized sports exceed the maturation and readiness of the participant, the positive aspects of participation can be negated. The nature of parental or adult involvement can also influence the degree to which participation in organized sports is a positive experience for preadolescents. This updates a previous policy statement on athletics for preadolescents and incorporates guidelines for sports participation for preschool children. Recommendations are offered on how pediatricians can help determine a child's readiness to participate, how risks can be minimized, and how child-oriented goals can be maximized.

Impact of a school-based health center on emergency department use by elementary school students

While school-based health centers (SBHC) improve student access to health services, it remains unclear if use of the centers can reduce hospital emergency department visits. This study evaluated the impact of an elementary school SBHC on emergency department visits by children enrolled in the center. Major reasons for visits included trauma (32%), otitis media (15%), upper respiratory infections (9%), and gastroenteritis (6%). Implementation of an elementary SBHC resulted in a significant decrease (p < 0.03) in non-urgent emergency department visits. No difference existed in urgent emergency department visits. Medicaid-insured children were more likely to use the emergency department than privately insured or uninsured children. Reducing emergency department visits can decrease medical costs and support the cost effectiveness of SBHCs.

Effects of a 6-month vitamin intervention on DNA damage in heavy smokers

Because their formation is associated with tumor development in specific tissues, DNA adducts have potential usefulness as intermediate end points in chemoprevention studies. To determine the efficacy of a combination of antioxidant vitamins (vitamins C and E and beta-carotene), a randomized clinical trial was conducted among heavy smokers using DNA damage as the end point. Immunological methods were used to measure polycyclic aromatic hydrocarbon-DNA adducts and oxidative DNA damage (8-oxo or hydroxydeoxyguanosine) in mononuclear and oral cells. A total of 121 subjects were randomized to the 6-month intervention and received either vitamins or placebo. Dropout rates were higher in the placebo than in the vitamin group; 65% of subjects in the vitamin group, but only 47% in the placebo group, provided specimens at 6 months. Plasma levels of all three antioxidants rose significantly in the vitamin group but not in the placebo group. All four measures of DNA damage decreased in both groups; the between-group differences were not statistically significant. These data do not provide clear evidence that antioxidant vitamin intake prevents DNA damage. However, the study demonstrates that DNA damage is a useful end point in chemoprevention trials.

Economic model of sustained-release bupropion hydrochloride in health plan and work site smoking-cessation programs

The development and application of an economic model designed to assess the specific costs and benefits of health plan coverage of smoking-cessation programs involving sustained-release bupropion hydrochloride are described. A cohort of 100,000 employees or health plan members and 60,000 adult dependents was followed from the start of the model to either retirement at age 65 or death at age 85. The model was used to compare outcomes for coverage versus no coverage of sustained-release bupropion hydrochloride as a component of a smoking-cessation benefit under four managed care plan scenarios and four employer scenarios. For the managed care scenarios involving coverage of bupropion sustained-release the overall decrease in health care costs over a 20-year period ranged from $7.9 million to $8.8 million; for every dollar spent covering smoking cessation, $4.10-$4.69 in health care costs was saved. For the employer scenarios, health care costs over 20 years decreased by $8.3 million to $14.0 million, and smoking-related indirect costs decreased an additional $5.1 million to $7.7 million; for every dollar spent covering smoking cessation, $5.04-$6.48 was saved. A model developed to assess the specific costs and benefits of covering sustained release bupropion hydrochloride as a component of a smoking-cessation benefit indicated cost savings for health plans and employers.

Corn husk oil lowers plasma LDL cholesterol concentrations by decreasing cholesterol absorption and altering hepatic cholesterol metabolism in guinea pigs

To test the hypocholesterolemic mechanisms of corn husk oil (CoHO), male Hartley guinea pigs were fed diets containing increasing doses of CoHO, either 0 (control), 5, 10, or 15 g/100 g, and 0.25 g/100 g cholesterol. A positive control group (LC) with low dietary cholesterol (0.04 g/100 g) was also included. Fat was adjusted to 15 g/100 g in all diets by the addition of regular corn oil. Plasma low density lipoprotein (LDL) cholesterol concentrations were 32, 55, and 57% (P < 0.0005) lower with increasing doses of CoHO. In addition, intake of CoHO resulted in 32 to 43% lower hepatic total and esterified cholesterol and 55 to 60% lower triacylglycerol concentrations compared with the control group (P < 0.01). CoHO intake resulted in plasma and hepatic cholesterol concentrations similar to those in guinea pigs from the LC group. The number of cholesteryl ester and free cholesterol molecules was higher in LDL from the control group than in LDL from the CoHO or the LC groups. Hepatic beta-hydroxy-beta-methylglutaryl-coenzyme A reductase activity was not modified by CoHO intake whereas cholesterol 7alpha-hydroxylase was up-regulated by 45 to 49% (P < 0.01) in the 10 and 15 g/100 g CoHO groups. Hepatic acyl coenzyme A cholesterol acyltransferase activity was down-regulated in a dose-dependent manner by 54, 58, and 63% with increasing doses of CoHO. CoHO intake resulted in increased fecal cholesterol excretion by 40 to 55% compared with the control and LC groups. Total fecal neutral sterol excretion was enhanced 42 to 55% by CoHO compared with the control group and by 59 to 68% compared with the LC group. The data from these studies suggest that CoHO has its hypocholesterolemic effect by decreasing cholesterol absorption and increasing bile acid output. These alterations in the intestinal lumen alter hepatic cholesterol metabolism and may affect the synthesis and catabolism of lipoproteins.

Immunohistochemical analysis of polycyclic aromatic hydrocarbon-DNA adducts in breast tumor tissue

Environmental carcinogens may play a role in the etiology of breast cancer, but the extent of their contribution is not yet defined. The aims of this study were to determine whether polycyclic aromatic hydrocarbon (PAH)-DNA adducts could be detected in stored paraffin blocks of breast tumor tissue (n=147) with an immunoperoxidase technique and whether they correlated with smoking history and/or mutant p53 protein expression. There was no significant difference in mean relative nuclear staining intensity in non-smokers (444+/-90, n=75), ever smokers (435+/-91, n=72), and current smokers (456+/-98, n=35). In either current or ever smokers, PAH-DNA adducts were non-significantly elevated in those with greater compared with lower exposure in relation to age at started smoking, years of smoking, cigarettes per day, and pack years. DNA damage levels were not elevated in tissues with compared with those without mutant p53 protein expression. These data demonstrate that immunohistochemical methods can be used to monitor DNA damage levels in archived breast tissues.

Anterior transposition of the superior oblique tendon in the treatment of oculomotor nerve palsy and its influence on postoperative hypertropia

PURPOSE

To determine whether postoperative hypertropia after anterior transposition of the superior oblique tendon without trochleotomy could be avoided with a simplified surgical approach.

METHODS

Eight patients with oculomotor nerve palsy (one patient was bilaterally affected) were retrospectively identified as having undergone anterior transposition of the superior oblique tendon without trochleotomy or vertical rectus muscle surgery between March 1992 and September 1998. The superior oblique tendon was cut at the medial border of the superior rectus muscle and placed 1-3.5 mm anterior to the medial insertion of the superior rectus muscle in each of these patients. Resection of the superior oblique tendon was not performed. The lateral rectus muscle was weakened, and no vertical rectus muscles were resected.

RESULTS

Preoperative deviations with the uninvolved eye fixating in primary position ranged from 20-90 prism diopters (delta) of exotropia (mean: 49.3 delta) and from 0-20 delta of hypotropia (mean: 11.25 delta). Postoperative horizontal deviations in the primary gaze position ranged from 12 delta of exotropia to 20 delta of esotropia. Six cases were aligned within 10 delta of exotropia or esotropia. Postoperative vertical deviations in the primary gaze position ranged from 2 delta of hypertropia to 8 delta of hypotropia. Six cases were aligned within 2 delta of deviation. Significant postoperative restrictive hypertropia, or new postoperative paradoxical ocular movements, did not occur in any patient. Patients who underwent follow-up >4 months maintained stable eye alignment.

CONCLUSION

Transposition of the superior oblique tendon without simultaneous resection or trochleotomy, or additional surgery to the vertical rectus muscle simplifies the surgical technique and eliminates subjective decision making regarding the amount of resection.

Late retinal progenitor cells show intrinsic limitations in the production of cell types and the kinetics of opsin synthesis

The seven major cell classes of the vertebrate neural retina arise from a pool of multipotent progenitor cells. Several studies suggest a model of retinal development in which both the environment and the progenitor cells themselves change over time (). To test this model, we used a reaggregate culture system in which a labeled population of progenitor cells from the postnatal rat retina were cultured with an excess of embryonic retinal cells. The labeled cells were then assayed for their cell fate choices and their kinetics of rod differentiation, as measured by opsin synthesis. The kinetics of opsin synthesis remained unchanged, but fewer postnatal cells adopted the rod cell fate when cultured with embryonic cells. There was an increase in the percentage of bipolar cells produced by postnatal progenitor cells, indicating a possible respecification of fate. The increase in bipolar cells could occur even after progenitor cells had completed their terminal mitoses. These alterations in cell fates appeared to be caused at least in part by a secreted factor released by the embryonic cells that requires the LIFRbeta/gp130 complex for signaling. Finally, although surrounded by 20-fold more embryonic cells, the postnatal cells did not choose to adopt any fates normally produced only by embryonic cells.

A founder effect in the newfoundland population reduces the Bardet-Biedl syndrome I (BBS1) interval to 1 cM

Bardet-Biedl syndrome (BBS) is a rare, autosomal recessive disorder; major phenotypic findings include dysmorphic extremities, retinal dystrophy, obesity, male hypogenitalism, and renal anomalies. In the majority of northern European families with BBS, the syndrome is linked to a 26-cM region on chromosome 11q13. However, the finding, so far, of five distinct BBS loci (BBS1, 1q; BBS2, 16q; BBS3, 3p; BBS4, 15q; BBS5, 2q) has hampered the positional cloning of these genes. We use linkage disequilibrium (LD) mapping in an isolated founder population in Newfoundland to significantly reduce the BBS1 critical region. Extensive haplotyping in several unrelated BBS families of English descent revealed that the affected members were homozygous for overlapping portions of a rare, disease-associated ancestral haplotype on chromosome 11q13. The LD data suggest that the BBS1 gene lies in a 1-Mb, sequence-ready region on chromosome 11q13, which should enable its identification.

The IOLAB, Inc pediatric intraocular lens study. AAPOS Reasearch Committee. American Association for Pediatric Ophthalmology and Strabismus

PURPOSE

This report is a summary of the data of the IOLAB, Inc pediatric intraocular lens (IOL) implantation investigation. The goal of this study was to evaluate the safety and efficacy of IOL implantation for the treatment of pediatric aphakia, pending approval by the Food and Drug Administration.

METHODS

From May 1981 to July 1994, a total of 1260 pediatric eyes received 171 styles of IOLs implanted by 361 US investigators. Preoperative, operative, and postoperative status reports over the first year were required for each eye entered into the study. Annual visit reports were requested thereafter to determine the long-term effects. The study was terminated in November 1995. All IOLs were obtained from IOLAB, Inc (now Chiron Vision Corp).

RESULTS

Reporting compliance was 98.3% for the preoperative and operative reports, 45.1% at 1 year, and 13.8% at 3 years. The subjects' ages ranged from younger than 1 yearto 17 years. Nine subjects (0.7%) were younger than 1 year, with the largest group of 533 subjects (42.3%) aged between 6 and 12 years atthe time of surgery. Cataract types were congenital (45.6%), traumatic (37.1%), secondary (11%), senile (0.95%), and unrecorded (5.4%). The IOL was implanted primarily in 74.8% of cases and secondarily in 21.4% of cases. There was no record in 3.8% of the cases. IOL types included anterior chamber (4.1%), iridocapsular (0.71%), posterior chamber (93.6%), and unrecorded (1.59%). There were 130 adverse reactions that required secondary surgical intervention. The most frequently performed surgical procedures included lens removal without replacement, vitrectomy, lens repositioning, and lens replacement. More than half (52%) of all eyes had a visual acuity of 20/200 or worse before surgery; amblyopia was reported in 21.1% of all participants at baseline. Postoperative visual acuity data were available on 563 eyes at 1 year after surgery. Overall, 52.8% of all eyes attained a visual acuity of 20/40 or better by the 1-year visit, and only 15.5% had visual acuity worse than 20/200. In general, the older patient, traumatic cataract, and secondary cataract categories were overrepresented in the better visual acuity outcome group.

CONCLUSION

The IOLAB, Inc pediatric IOL study is the first multiple-practitioner, national study designed to evaluate the safety and efficacy of IOL implantation in children. The study results are compromised by the almost 50% loss of follow-up at the 1-year evaluation. Other variables that most likely influenced outcome results were the methods of cataract extraction, medical management, and IOL design, all of which evolved dramatically over the time course of the study. Despite these issues, pediatric IOL implantation seems to be a reasonable treatment modality for aphakia, on the basis of the available 1-year follow-up data of the remaining 45.1% of eyes in the study.

Microphthalmia-associated transcription factor (MITF) locus lacks linkage to human vitiligo or osteopetrosis: an evaluation

The microphthalmia-associated transcription factor (MITF) locus has been mapped to human chromosome 3p12-p14.1, and encodes a basic helix-loop-helix zipper (bHLH-ZIP) protein homologous to a number of transcription factors. Numerous mutations at the mouse microphthalmia (mi) locus have been described, and all have reduced or absent pigmentation of the eyes, ears, and/or pelage, with some genotypes exhibiting small or absent eyes and osteopetrosis. The mivit/vit mutation at the mouse mi locus produces a postnatal depigmentation that resembles human vitiligo. The mice homozygous for this mi allele show a progressive loss of cutaneous, hair and ocular pigmentation with age. Vitiligo, an acquired depigmentary disorder, is characterized by patchy depigmentation of skin that generally begins around puberty and tends to become more progressive over time. There is suggestive evidence that human vitiligo may be inherited; however, the mode of inheritance is still debated and the pathogenesis is not clearly delineated. The human disorder osteopetrosis is characterized by a generalized net accumulation of skeletal mass and results from reduced osteoclast function in the bone. This is an inherited disorder and has been associated with mi in a mutant mouse. Therefore, the possible involvement of the MITF locus in the pathogenesis of either familial vitiligo or osteopetrosis was investigated. Linkage analysis was performed using microsatellite polymorphic markers D3S2465, D3S1261, and D3S1766 on genomic DNA from 26 families with vitiligo/osteopetrosis. D3S1261 is physically located at or near the MITF locus, while D3S2465 and D3S1766 are flanking the locus at about 17.5 cM genetic distance each side. Evidence from LOD score analysis surprisingly indicated that none of the families with vitiligo or osteopetrosis are linked to these short tandem repeat polymorphisms (STRPs). Thus, the human homolog (MITF) of the mouse mi gene, a good candidate gene at the phenotypic level, may not be involved in the pathogenesis of familial human vitiligo or osteopetrosis.

Costs of smoking: a focus on maternal, childhood, and other short-run costs

Estimating the costs attributable to smoking is helpful for evaluating appropriate tax policy, informing both public and private managers of health care, and evaluating alternative smoking cessation programs. While the smoking-attributable costs of chronic conditions have been well studied, these costs are less relevant to health maintenance organizations (HMOs) and employers whose populations are younger and transient. Costs incurred in the short run, such as those related to smoking during pregnancy and environmental tobacco smoke exposure (ETS) of children, are more relevant. In this article, the authors review studies of these sources of smoking-attributable costs as well as studies that focus on smoking-attributable outcomes and costs from the employer or HMO perspective. Subsidies may be necessary to induce employers to recognize the full social benefits of smoking cessation programs.

Genetic heterogeneity of Bardet-Biedl syndrome in a distinct Canadian population: evidence for a fifth locus

Bardet-Biedl syndrome (BBS) is a rare, autosomal recessive disease characterized by retinal dystrophy, renal structural abnormalities, obesity, dysmorphic extremities, and hypogenitalism in males. BBS is genetically heterogeneous with four known loci: BBS1 (11q), BBS2 (16q), BBS3 (3p), and BBS4 (15q). The prevalence of BBS in Newfoundland is approximately 10-fold greater than in Switzerland (1:160,000) and similar to the prevalence among the Bedouin of Kuwait (1:13,500). A population-based genetic survey was performed on 17 BBS families from the island portion of the province of Newfoundland, a comparatively isolated region of Canada. The families in the study had a total of 36 well-documented, affected individuals with 12 families having 2 or more affected individuals. Linkage at each of the four known loci was tested with two-point linkage and haplotype analysis. Three of the 17 kindreds showed linkage to 11q, 1 to 16q, and 1 to 3p. The latter is the first BBS3 family identified in a population of northern European descent. Six families remain undetermined because of poor pedigree structure or inconclusive haplotype analyses. Six families were excluded from all four known BBS loci, indicating that there is at least a fifth BBS locus (BBS5).

Multiplexed short tandem repeat polymorphisms of the Weber 8A set of markers using tailed primers and infrared fluorescence detection

Short tandem repeat polymorphism (STRP) markers have become important reagents for mapping genetic diseases. These markers are available as screening sets, which are located in all chromosomes at discrete intervals, allowing the entire genome to be analyzed. Mapping studies that include many individuals in the analysis necessitate the production of large numbers of genotypes. In an effort to increase the efficiency and lower the cost of using these STRP screening sets, we have divided the amplification primers of the Weber 8A screening set into groups that can be amplified in single polymerase chain reaction (PCR) amplification reactions, resulting in a reduction of both time and cost. Fluorescently-labeled amplification products were produced using a three primer reaction. The forward STRP amplification primer for each marker contained a 19 bp sequence at the 5' end. A fluorescently-labeled primer, with a sequence identical to the 19 bp tail, was added to the amplification reaction as the sole source of fluorescent label. The STRP banding pattern is detected using an automated fluorescent DNA sequencer. Use of this multiplexed genomic screening set should greatly enhance the mapping of human disease loci.

Clueless: parental knowledge of risk behaviors of middle school students

OBJECTIVES

To determine parental knowledge of risk behaviors of their middle-school-aged children and to compare that knowledge with behaviors reported by the students.

DESIGN

Confidential surveys were administered to 194 poor and middle-class middle school students and their parents.

INTERVENTION

None.

MAIN OUTCOME MEASURE

Compare parental awareness and student admission of risk behaviors.

RESULTS

Students and parents agree on the prevalence of some risk behaviors, including use of a seat belt, use of a bicycle helmet, arrest by police, use of diet pills, and attempts to lose weight through dieting and exercise. Small differences in perception, which were not statistically significant but which could be defined as trends, were found relating to the prevalence of dieting, exercising, or vomiting to lose weight. Statistically significant differences were found in the perceptions of the prevalence of the following risk behaviors: carrying a weapon to school (P<.001), LSD (lysergic acid diethylamide) or cocaine use (P=.02), suicide attempt (P<.001), sexual intercourse (P<.001), alcohol use (P<.001), tobacco use (P<.001), and marijuana use (P<.001). In many cases, parents dramatically underestimated the prevalence of these behaviors in students.

CONCLUSIONS

Parents are largely ignorant of the extent to which their adolescents are involved in major risk behaviors. Educating parents in this area encourages them to support comprehensive health education curricula and other preventive programs in schools and communities.