Analysis of variability of clinical manifestations in Waardenburg syndrome

Expression of clinical findings of Waardenburg syndrome type 1 (WS1) and type 2 (WS2) is extremely variable. Using our collection of 26 WS1 and 8 WS2 families, we analyzed the occurrence, severity, and symmetry of clinical manifestations associated with WS. We found significant differences between WS1 and WS2 in deafness, and in pigmentary and craniofacial anomalies. Factor analysis was used to identify manifestations which covaried, resulting in 2 orthogonal factors. Since mean factor scores were found to differ when compared between WS1 and WS2, we suggest that these factors could be useful in distinguishing WS types. We found that the WS gene was transmitted from mothers more often than from fathers. We also extensively examined the W-Index, a continuous measure of dystopia canthorum. Our data suggest that use of the W-Index to discriminate between affected WS1 and WS2 individuals may be problematic since 1) ranges of W-Index scores of affected and unaffected individuals over-lapped considerably within both WS1 and WS2, and 2) a considerable number of both affected and unaffected WS2 individuals exhibited W-index scores consistent with dystopia canthorum. Misclassification of families may have implications for risk assessment of deafness, since WS2 families have been reported to have greater incidence of deafness, as confirmed in our study. © 1995 Wiley-Liss, Inc.     

α2-Adrenergic receptor subtype alterations in the brainstem in the sudden infant death syndrome

Background: The sudden infant death syndrome (SIDS) is still the main cause of postneonatal infant death. However, the causes and mechanisms of SIDS have never been completely elucidated. Catecholamines, via α2-adrenergic receptor (α2-AR) interactions, are known to influence brainstem autonomic and respiratory activity. Aims: To examine the catecholaminergic system abnormalities in SIDS victims, we investigated the alterations of α2-AR subtypes. Subjects and methods: We examined the developmental changes of α2-AR subtypes in the brainstem, especially in cardiorespiratory nuclei, in 21 SIDS victims and 17 age-matched controls by means of immunohistochemical methods. For statistical analysis, the χ²-test or Fisher’s exact probability test was performed. Results: There was a significant decrease in α2A-AR immunoreactivity in the solitary nucleus and ventrolateral medulla (VLM) in the medulla oblongata in SIDS victims compared with in control cases, but there were no significant differences of the α2B and α2C-AR immunoreactivity in the brainstem between SIDS victims and controls. Conclusion: α2A-AR immunoreactivity was selectively decreased in the solitary nucleus and VLM in the medulla oblongata in SIDS victims, so there was no possibility that it was secondary to chronic hypoxia or repeated ischemia. It may be related to some impairment of the cardiorespiratory neuronal system. Therefore, SIDS victims may be vulnerable to asphyxia, hypoxia, and/or hypercapnia, and fail to exhibit brainstem responses.     

Assessment of the genetic causes of recessive childhood non-syndromic deafness in the UK - implications for genetic testing

Approximately one in 2000 children is born with a genetic hearing impairment, mostly inherited as a non-syndromic, autosomal recessive trait, for which more than 30 different genes have been identified. Previous studies have shown that one of these genes, connexin 26 (GJB2), accounts for 30-60% of such deafness, but the relative contribution of the many other genes is not known, especially in the outbred UK population. This lack of knowledge hampers the development of diagnostic genetic services for deafness. In an effort to determine the molecular aetiology of deafness in the population, 142 sib pairs with early-onset, non-syndromic hearing impairment were recruited. Those in whom deafness could not be attributed to GJB2 mutations were investigated further for other mapped genes. The genetic basis of 55 cases (38.7%) was established, 33.1% being due to mutations in the GJB2 gene and 3.5% due to mutations in SLC26A4. None of the remaining 26 loci investigated made a significant contribution to deafness in a Caucasian population. We suggest that screening the GJB2 and SLC26A4 genes should form the basis of any genetic testing programme for childhood deafness and highlight a number of important issues for consideration and future work.     

Skeletal dysplasia syndrome with progeroid appearance,characteristic facial and limb anomalies,multiple synostoses,and distinct skeletal changes: A variant example of the Lenz–Majewski syndrome

Here we report a 10 year-old mentally retarded, deaf boy with a unique pattern of anomalies: progeroid appearance, characteristic facial and limb anomalies, multiple synostoses, and distinct skeletal changes. He represents a variant example of “hyperostotic dwarfism” as delineated by Lenz and Majewski.     

上海市青浦区噪声作业人员听力状况分析

目的 了解近3年青浦区噪声作业人员的听力变化趋势,为预防职业性噪声聋提供依据。方法 收集2018-2020年青浦区噪声作业人员在岗期间的听力数据,并运用SPSS软件进行统计分析。结果 噪声作业人员的双耳高频平均听阈升高率2018-2020年分别为6.09%、5.16%、3.06%,呈逐年降低趋势(P<0.01);男性升高率高于女性(P<0.01);随着年龄、工龄的增加,升高率呈现增高趋势(P<0.01)。双耳高频平均听阈升高率位于前三的行业分别为建筑业(28.57%)、租赁和商务服务业(18.72%)以及批发零售业(13.89%)。结论 噪声作业人员的职业病防控工作仍不可放松,应及时对噪声作业重点人员进行有针对性的干预。     

扩张型心肌病QT离散度对于猝死的临床意义

目的　探讨QT离散度对于扩张型心肌病 (DCM)者猝死的诊断价值。方法　回顾性分析因DCM而猝死的 1 0例病人 ,以及同期的 1 8例非心律失常的DCM病人 ,分别测定其入院的首次心电图的QT离散度 (QTd) ,进行比较研究。结果　发现 1 0例猝死病人的QTd均 >440ms。结论　QTd >440ms对于预测DCM猝死有一定的临床诊断价值     

小脑和脑干梗塞致突发性耳聋

目的:了解小脑和脑干梗塞引起的突发性耳聋的临床特点.探讨其发病机制.方法:回顾性分析12例小脑和脑干梗塞所致突发性耳聋的临床资料.结果:该组患者主要临床表现为耳聋、眩晕、耳鸣、眼震、同侧颜面麻木感.头颅CT或MRI发现小脑或脑干有小于2 cm的梗塞灶.结论:发病机制主要为小脑前下动脉(AlCA)供血不足使小脑脑桥角或脑干缺血,损伤该区域的耳蜗神经和听神经传导通路,导致耳聋.小脑和脑干梗塞的诊断主要依据临床表现、CT或MRI检查.     

Temporal Bone Histopathology in Connexin 26–Related Hearing Loss

Objective: Mutations in GJB2, a gene that encodes a gap junction protein, Connexin 26 (Cx26), are responsible for approximately one third of sporadic severe‐to‐profound or profound congenital deafness and half of severe‐to‐profound or profound autosomal recessive nonsyndromic hearing loss (ARNSHL). Mouse mutants homozygous for knockouts of this gene are nonviable, precluding histopathologic studies of the associated inner ear pathology in this animal model. Therefore, we studied archival temporal bone sections to identify temporal bone donors with Cx26‐related deafness. Study Design: Temporal bone donors with a history of congenital severe‐to‐profound or profound deafness were identified in the registry of the Temporal Bone Library at the University of Iowa. Histological findings were interpreted in a blinded fashion. DNA extracted from two celloidin‐embedded mid‐modiolar sections from each temporal bone was screened for the 35delG Cx26 mutation. The entire coding region of Cx26 was screened for other deafness‐causing mutations if the 35delG mutation was detected. Results: Of five temporal bone donors with congenital severe‐to‐profound deafness, one donor was found to have Cx26‐related deafness. This individual was a Cx26 compound heterozygote, carrying the 35delG mutation and a noncomplementary Cx26 missense mutation on the opposing allele. Microscopic evaluation of this temporal bone showed no neural degeneration, a good population of spiral ganglion cells, near‐total degeneration of hair cells in the organ of Corti, a detached and rolled‐up tectorial membrane, agenesis of the stria vascularis, and a large cyst in the scala media in the region of the stria vascularis. Conclusion: This study is the first to report the temporal bone histopathology associated with Cx26‐related deafness. Preservation of neurons in the spiral ganglion suggests that long‐term successful habilitation with cochlear implants may be possible in persons with severe‐to‐profound or profound Cx26‐related deafness.     

A Dutch family with progressive sensorineural hearing impairment linked to the DFNA2 region

We studied a Dutch family with DFNA2-linked progressive sensorineural hearing impairment (SNHI). Recent audiograms were obtained from 18 of the affected persons (age 7–81 years) and were used in a gene-linkage analysis. Linear regression analysis of the audiograms, using binaural mean thresholds, disclosed on average a descending slope of approximately 10 dB/octave at any age and an annual threshold increase at any frequency of about 0.7 dB/year. There may have been substantial congenital impairment at higher frequencies, but longitudinal analysis of hearing impairment in the youngest case, who was followed from age 5 years, suggested that the most significant changes in hearing may have occurred in the first two decades of life. Linkage analysis was carried out with special attention to the DFNA2 region because hearing trends were very similar to families previously linked to DFNA2. Linkage to DFNA2 was established with maximum lod scores of 4.7 and 3.2 for the flanking markers of the DFNA2 region (D1S432;MYCL1). Received: 25 February 1999 / Accepted: 11 June 1999