High-resolution mapping of the 8p23.1 beta-defensin cluster reveals strictly concordant copy number variation of all genes

One unexpected feature of the human genome is the high structural variability across individuals. Frequently, large regions of the genome show structural polymorphisms and many vary in their abundance. However, accurate methods for the characterization and typing of such copy number variations (CNV) are needed. The defensin cluster at the human region 8p23.1 is one of the best studied CNV regions due to its potential clinical relevance for innate immunity, inflammation, and cancer. The region can be divided into two subclusters, which harbor predominantly either alpha- or beta-defensin genes. Previous studies assessing individual copy numbers gave different results regarding whether the complete beta-defensin cluster varies or only particular genes therein. We applied multiplex ligation-dependent probe amplification (MLPA) to measure defensin locus copy numbers in 42 samples. The data show strict copy number concordance of all 10 loci typed within the beta-defensin cluster in each individual, while seven loci within the alpha-defensin cluster are consistently found as single copies per chromosome. The exception is DEFA3, which is located within the alpha-defensin cluster and was found to also differ in copy number interindividually. Absolute copy numbers ranged from two to nine for the beta-defensin cluster and zero to four for DEFA3. The CNV-typed individuals, including HapMap samples, are publicly available and may serve as a universal reference for absolute copy number determination. On this basis, MLPA represents a reliable technique for medium- to high-throughput typing of 8p23.1 defensin CNV in association studies for diverse clinical phenotypes.     

Copy number variations in neurodevelopmental disorders

Common neurodevelopmental disorders (including autism, speech and language delay, schizophrenia, epilepsy and intellectual disability) have complex aetiology, which is predominantly genomic, but also environmental in origin. They share a paradox, in that high heritability is matched by lowered fecundity, placing them under negative genetic selection. This implicates variants of recent origin, such as de novo mutations or common, very low-risk polymorphisms that escape negative selection. High or moderate risk variants have been discovered by chromosome analysis, genome sequencing and copy number variant (CNV) detection, including a 3Mb deletion causing 22q11.2 deletion syndrome (Velo-Cardio-Facial Syndrome) that has penetrance of up to 50% for schizophrenia. More recently, rare, recurrent and often de novo pathogenic CNVs, including deletions at NRXN1, 1q21.2, 15q11.2 and 15q13.3, 16p11.2 and duplications at VIPR2 and 16p13.11, have also been discovered. These have several unique features that differentiate them from Mendelian disease mutations in that they have incomplete penetrance, with moderate-to-high odds ratios for risk, and show diagnostic pleiotropy, increasing risk across the neurodevelopmental disorder spectrum. Some are also syndromic, with characteristic features such as facial dysmorphology, and other specific risks such as aortic dissection or obesity, implying that they might be better classified as distinct diagnoses. The discovery of pathogenic CNVs provide new opportunities for translation leading to patent benefit, including improvements in clinical genetic diagnosis and genetic counselling, the possibility of clinician decision-making tools for risk prediction, and the identification of drug targets and implementation of personalised medicine using stratification by genotype.     

Measurement of light touch perception threshold by contingent negative variation

Summary An objective method developed to measure the threshold of light touch perception using contingent negative variation (CNV) is described. The light touch stimulus was a slight indentation of the skin produced through a displacement controlled stimulating probe (tip diameter of 2 mm). It was applied as the conditioning (S1) stimulus of the classical CNV paradigm of S1, S2, and R. To increase the CNV amplitude, the S2 stimulus was either a red or a yellow LED. The subjects were required to respond to only one of two by pressing a button. When the light touch stimulus was perceived, the CNV was recorded in all 19 healthy adult volunteers. In 14 of them, a systematic determination of the threshold of the ball of the thumb and index finger, thenar, hypothenar, face, shoulder, anterior thigh, foot dorsum and great toe ball, have been done. The thresholds of the light touch perception as defined by objective CNV measurement are very close to the results of the subjective psychophysiological determinations in normals. The amplitude of the averaged CNV (12 responses) started to decrease when stimulus intensity was reduced to the point that the subjects were able to perceive only a fraction of the presented touch stimuli. We believe, therefore, that the objective CNV determination of the light touch perception threshold is precise and sensitive enough to be used in research as well as in clinical applications.     

Fear conditioning, preparedness, and the contingent negative variation

Psychophysiological research on preparedness has previously focused on autonomic nervous system parameters. The present study used electrocortical indices of fear conditioning. Subjects (n= 10) were tested under fear-relevant and fear-irrelevant conditions (1 week apart, order of conditions counterbalanced). Each condition comprised acquisition and extinction sessions. The contingent negative variation (CNV) was elicited in anticipation of forewarned slides (fear relevant: small animals; fear irrelevant: landscapes). In acquisition, reinforced conditioned stimulus (CS+) (but not nonreinforced conditioned stimulus [CS-]) slides were followed by white noise as an unconditioned stimulus (UCS). In extinction, the UCS was omitted. In the fear-relevant condition, CNV amplitude was significantly larger for CS+ than CS- in both acquisition and extinction. In the fear-irrelevant condition, CNV differentiation between CS+ and CS- was weak in both sessions. CNV was significantly larger in the fear-relevant than in the fear-irrelevant condition, for CS+ but not CS-. The findings are consistent with a preparedness interpretation and suggest that CNV under such circumstances may represent an automatic affective response to fear-relevant stimuli. Electrocortical measures could be particularly useful in examining information processing mechanisms in phobia and cognition-affect relationships generally.     

经瞳温热疗法治疗湿性年龄相关黄斑变性的疗效观察

目的：探讨经瞳温热疗法（transpupillary thermotherapy,TTT）治疗湿性年龄相关黄斑变性（age-related macular degeneration,ARMD）的初步疗效.方法：对9例14眼经眼底检查、荧光素眼底血管造影（fundus fluorescein angiography,FFA）和吲哚菁绿眼底血管造影（indocyanine green angiography,ICGA）确诊为湿性ARMD（12眼为隐匿型、2眼为经典型）的患眼行TTT治疗.根据脉络膜新生血管膜（choroidal neovascular membrane,CNV）的范围选择不同的光斑大小和能量,术后对眼底改变、视力、眼底血管造影复查,随访1～22（平均11.67）mo,以观察疗效.结果：经TTT治疗后,至末次复查时11眼（79%）出血、水肿、渗出消失、病灶斑痕化,3眼（21%）的出血、水肿、渗出明显减轻.5位患者的8眼患眼有TTT后的FFA及ICGA复查,显示其中6眼的原病灶渗漏消失、CNV消退,2眼的渗漏明显减轻.治疗后视力提高的有4眼（29%）,稳定的有7眼（50%）,下降的有3眼（21%）.除2位患者的2只患眼（14%）分别在第一次治疗后的第4和第5mo经造影复查后,接受了原病灶的再次TTT外,其余患眼（86%）均只进行了一次TTT.结论：TTT对湿性ARMD有较明确的疗效,经济安全,其远期疗效需更多病例观察.