Ring chromosome 15 and 15qs+ mosaic: Clinical and cytogenetic behaviour spanning 29 years

A phenotypic female with mild mental retardation, minor facial anomalies, and short stature has been evaluated clinically and cytogenetically over 29 years. At age 59, she remains physically well and shows no signs of dementia. Cytogenetic analysis, performed on peripheral blood specimens on 10 occasions between 1961 and 1990, showed mosaicism with one cell line containing a large stable ring (15) chromosome and another cell line without the ring but with a 15qs +. The different cell lines remained constant. The case provides information on the natural history of the ring chromosome 15 syndrome.     

Functional role of low-voltage-activated dihydropyridine-sensitive Ca channels during the action potential in adult rat sensory neurones

Neuronal cell firing is crucial to nerve-nerve communication. The ability to produce consecutive action potentials is related to the activation of inward currents after each upstroke. If fast Na current is indeed responsible for the overshoot, it is still unclear which current drives membrane voltage to the Na threshold. In this study we present evidence that in adult rat sensory neurones a dihydropyridine-sensitive Ca channel exists in addition to the well characterized L-type, or high-threshold Ca channel. During stimulated action potential trains, L-type Ca channels open during the excitation wave, whereas activity of the other dihydropyridine-sensitive Ca channel was observed primarily between action potentials. This second Ca pathway shows remarkably long openings at negative potentials after a series of positive prepulses. The nerve action potential and the repetitive firing work as a physiological Ca channel facilitation mechanism. Therefore, we suggest that this novel Ca conductance provides inward current, between two consecutive action potentials, able to modulate the frequency of neuronal bursts. Received: 3 August 1995/Received after revision: 9 October 1995/Accepted: 10 October 1995     

青岛地区D6S477等五个短串联重复序列基因座的遗传多态性研究

目的 了解D6S477等5个基因座在青岛地区汉族群体中基因型分布及等位基因频率等遗传多态性数据，初步探讨其应用价值。方法 收集200名青岛地区汉族无关个体的静脉血，ACD抗凝，采用Chelex法提取DNA，应用聚合酶链反应技术，扩增D6S477、D9S1118、D18S865、D19S400和D20S161基因座的短串联重复序列，聚丙烯酰胺凝胶垂直电泳，银染显色分型。结果 获得了青岛地区汉族群体上述5个基因座的等位基因频率，基因型分布均符合Hardy-Weinberg平衡（P〉0．05）。结论 这5个基因座在青岛地区汉族群体中有较高的非父排除率和个人识别机率，在遗传学研究中有较高的应用价值。     

Duplication of distal 22q

We report on three patients with duplication of distal 22q. One patient is a de novo carrier of the translocation t(21;22) (p13;q11), the other two are offspring of a translocation carrier t(10;22) (q26;q12). The clinical manifestations of these patients demonstrate the variability of the dup(22q) syndrome.     

Separation of temperature sensitive and temperature insensitive components of the postsynaptic potentials in the frog motoneurons

Intracellular measurements were made in the in situ spinal cord of the frog at temperatures below 5 degrees C. Responses to volleys in the sciatic nerve, in the descending fibres and in the motor axons were studied. About 30% of the motoneurons responded to sciatic volleys with 1-3 ms segmental latency, which was short enough to assume electrotonic mediation of these responses. Another group of motoneurons responded with 6-8 ms latency, i.e. with the expected delay at chemical synapses at low temperature. Latency distribution of the sciatic-evoked postsynaptic potentials was clearly bimodal in contrast with that found at higher temperatures. Postsynaptic discharges occurred with rather long latency and they were attributed to chemically-mediated excitation. Some of the postsynaptic potentials to descending volleys also occurred with quite short latency, indicating possible electrotonic transmission from supraspinal centres to motoneurons. Latency distribution of the action potentials evoked from the motor axons was bimodal, corresponding to the different, i.e. antidromic and recurrent facilitatory, mechanism of these spikes. Calculated Q10 ratios for the sciatic-evoked reflex discharges and the afferent fibre volleys were about 2.3 and 1.8, respectively. We concluded that cooling helps to separate postsynaptic potentials according to their electrotonic and chemical mediation and that electrotonic excitation does not seem to have a primary role in the generation of postsynaptic discharges initiated by dorsal root volleys in the frog.     

鄂伦春族Y染色体短串联重复序列多态性研究

目的 调查鄂伦春族Y染色体上10个短串联重复序列基因座及单倍型的遗传多态性。方法 应用PCR和变性聚丙烯酰胺凝胶电泳结合银染显色分型技术，检测102名无关系鄂伦春族男性血样。结果 在DYS392、DYS438、DYS439、DYS456、DYS459、DYS460、DYS461、DYS462、DYS389Ⅰ、DYS389Ⅱ等10个基因座中共检出44个等位基因，等位基因频率分布在0．418（DYS461）至0．727（DYS389Ⅰ）之间，除了DYS461（0．418）和DYS462（0．479）以外，其余等位基因频率均大于0．5。由10个基因座组成的Y染色体单倍型系统单倍型有101种，单倍型频率0．99。结论 上述10个Y-短串联重复基因座在鄂伦春族群体中具有较好的多态性，单倍型具有很高的遗传多态性。     

Brunner's gland metaplasia of residual jejunum developed long after wide resection of the small intestine

We report a rare case in which mucous glands, similar to pyloric or Brunner's glands, developed in the residual jejunum (46 cm in length) long after wide resection of the small intestine. The mucous glands were observed in the mucosal and submucosal layers near the duodenum, and the mucin showed a positive reaction by paradoxical concanavalin A staining and immunoreactivity for HIK-1083, which were histochemically the same as those in the pyloric/Brunner's glands. This type of metaplasia in the small intestine without ulceration has not been described in the literature so far. It was speculated that these glands developed as a defense response or adaptation against relatively excessive acid due to the short small intestine.     

Further delineation of the Beemer–Langer syndrome using concordance rates in affected sibs

Six familial cases of the Beemer–Langer syndrome (BLS) were analyzed to further elucidate the spectrum and frequency of anomalies observed in this disorder. Preaxial polydactyly was found in 3/6 affected sibs, and, therefore, its frequency previously may have been underestimated. Some patients, described as infants affected with the Majewski syndrome (MS) or “atypical” short rib-poly-dactyly conditions, may indeed have BLS. A high frequency of brain defects (16/26) and cleft tongue, oral frenula, and/or natal teeth (13/29) widens the list of typical findings in this syndrome. The specific type of tibial defect seems to be the most important discrimination of the MS and the BLS. © 1994 Wiley-Liss, Inc.     

Paternal mosaicism for a novel PBX1 mutation associated with recurrent perinatal death: Phenotypic expansion of the PBX1‐related syndrome

Autosomal dominant (de novo) mutations in PBX1 are known to cause congenital abnormalities of the kidney and urinary tract (CAKUT), with or without extra‐renal abnormalities. Using trio exome sequencing, we identified a PBX1 p.(Arg107Trp) mutation in a deceased one‐day‐old neonate presenting with CAKUT, asplenia, and severe bilateral diaphragmatic thinning and eventration. Further investigation by droplet digital PCR revealed that the mutation had occurred post‐zygotically in the father, with different variant allele frequencies of the mosaic PBX1 mutation in blood (10%) and sperm (20%). Interestingly, the father had subclinical hydronephrosis in childhood. With an expected recurrence risk of one in five, chorionic villus sampling and prenatal diagnosis for the PBX1 mutation identified recurrence in a subsequent pregnancy. The family opted to continue the pregnancy and the second affected sibling was stillborn at 35 weeks, presenting with similar severe bilateral diaphragmatic eventration, microsplenia, and complete sex reversal (46, XY female). This study highlights the importance of follow‐up studies for presumed de novo and low‐level mosaic variants and broadens the phenotypic spectrum of developmental abnormalities caused by PBX1 mutations.