The primate subarcuate fossa and its relationship to the semicircular canals part II: adult interspecific variation

Studies have reported an empirical link between the size of the semicircular canals and locomotor agility across adult primates. In this paper, we investigate the possibility that this relationship does not follow from the function of the semicircular canals to sense head rotations, but rather reflects spatial constraints imposed by the subarcuate fossa. The latter sits among the three canals and contains the petrosal lobule of the cerebellar paraflocculus, a structure involved in neural processing of locomotion-related eye movements. Hence, it is feasible that agility-related variations of lobule and fossa size affect the arc size of the surrounding semicircular canals. The present study tests such hypothetical correlations by evaluating canal size, fossa size, and agility among extant adult primates. Phylogenetically informed multivariate regression analyses show that, after controlling for body mass, the size of the subarcuate fossa has a significant positive effect on the overall size of the anterior canal and the width of the posterior canal. Multivariate regressions involving the height of the posterior canal and overall size of the lateral canal are not significant. Further bivariate analyses confirm that fossa size is unlikely to play a role in the previously reported link between agility and the size of the posterior and lateral canals. However, fossa size, especially its opening though the arc of the anterior canal, cannot be excluded as a factor that influences the size of the anterior canal more than agility. The findings show that the most reliable functional signals pertaining to locomotion in species that possess a patent subarcuate fossa are likely to come from the lateral canal and are least likely to come from the anterior canal.     

Dandy�CWalker malformation: An incidental finding

Dandy–Walker malformation (DWM) is a rare intracranial congenital abnormality that affects the cerebellum and some of its components; particularly cerebellar vermis, fourth ventricle and is characterized by an enlarged posterior fossa. Although there is an extensive list of signs attributed to DWM, final diagnosis is solely dependent on imaging techniques as there are no signs that are characteristic of DWM. This article reports a case with DWM who was diagnosed by magnetic resonance imaging.     

Monitoring therapeutic efficacy of decompressive craniotomy in space occupying cerebellar infarcts using brain-stem auditory evoked potentials

Brain-stem auditory evoked potentials (BAEPs) have been used to gauge effects of brain-stem dysfunction in humans and animal models. The purpose of this study was to evaluate the usefulness of BAEP in monitoring patients undergoing decompressive surgery of the posterior fossa for space occupying cerebellar infarcts.We report on serial BAEP recordings in 11 comatose patients with space occupying cerebellar infarcts undergoing decompressive craniotomy. BAEP studies were performed within 12 h after admission, 24 h following surgery and prior to extubation. BAEP signals were analyzed using latency determination and cross-correlation.Following surgery, 9 patients regained consciousness; 2 patients persisted in a comatose state and died subsequently.BAEP interpeak latency (IPL) I-V assessed prior to surgery exceeded normal values in all patients in whom it could be reliably measured (N = 9). Following decompressive surgery BAEP wave I-V IPL normalized in 5 patients, but remained prolonged despite dramtic clinical improvement in 4 patients. We prospectively computed the coefficient of cross-correlation (MCC) of combined ipsilateral BAEP trials after right and left ear stimulation. In all patients increasing MCC was associated with clinical improvement. Unchanging or decreasing MCC indicated poor outcome.We conclude that serial BAEP studies are an appropriate perioperative monitoring modality in patients with space occupying cerebellar infarcts undergoing decompressive surgery of the posterior fossa.Our study suggests advantages of cross-correlation analysis as an objective signal processing strategy; relevant information can be extracted even if BAEP wave discrimination is impossible due to severe brain-stem dysfunction.     

The subarcuate fossa and cerebellum of extant primates: comparative study of a skull-brain interface

The subarcuate fossa of the petrosal bone houses the petrosal lobule of the cerebellar paraflocculus. Although the subarcuate fossa can be extensive, little is known about its relative size and distribution in primates. Studies indicate parafloccular involvement with cerebellar areas coordinating vestibular, visual, auditory, and locomotor systems. Hypotheses have proposed a role for the paraflocculus in vestibular-oculomotor integration, caudal muscle control, autonomic function, and visual-manual predation. This study examines the morphology and relative extent of the subarcuate fossa/petrosal lobule in a range of living primates. Methods include study of postmortem specimens representing nine mammalian orders, and qualification of the volume of the subarcuate fossa and endocranial cavity in 155 dry primate crania of 36 genera. Results show that, in mammals, the size and morphology of the petrosal lobule is directly related to that of the subarcuate fossa. Craniometric analysis shows that the ratio of subarcuate fossa volume to endocranial volume is largest in lemuriforms. The largest ratio is in Microcebus and Hapalemur. Lorisids show a significant reduction in the size of the subarcuate fossa to almost 50% below the lemuriform mean. Tarsius is near the lemuriform mean. Among platyrrhines, the ratio is high, but significantly reduced compared to lemuiforms. The highest platyrrhine ratio is seen in Ateles, the lowest in Saimiri and Alouatta. Atelids are significantly elevated compared to cebids. In cercopithecids, the fossa is significantly reduced compared to platyrrhines. The trend toward reduction of the cercopithecid fossa is most pronounced in Theropithecus and least evident in Presbytis. In hominoids, the fossa is present only in Hylobates. In great apes and humans, other than Gorilla, the petromastoid canal occupies a similar location to the subarcuate fossa of other primates, but is not homologous to it. Neither the subarcuate fossa nor the petromastoid canal are present in Gorilla. A graded reduction of the subarcuate fossa/petrosal lobule is evident among primates which evolved later in time. The relative size of this cerebellar lobule within primates may reflect size-related factors and/or degree of neocortical evolution as these relate to usage of a specific sensory-mediated locomotor behavior. The subarcuate fossa may serve as an indicator to the differentiation of the petrosal lobule of the paraflocculus in fossil forms.     

A craniometric study of sagittal craniosynostosis (SC).

Twenty cases of sagittal craniosynostosis (SC) were compared with the linear and angular values of the normal statistical material for the same age and sex. There were significantly increased values of the length of the skull (LI) and the height of the frontal arch (FNBR) and significantly decreased width (WI) and height of the skull (HI) as well as the depth of the cerebellar fossa (PEP). The length of the anterior cerebral fossa (LEA) remained within normal limits and the distance BRPI between bregma (BR) and the internal protuberance (PI) was within normal limits or increased. The angular value of the basal angle (angle NT-BA, AB2) decreased significantly and the angle NTNO (angle between the lines NT and NO) and the angle BRTPI (the angle between the lines TBR and TPI) were significantly increased. The cephalic index (CI) was significantly decreased. The cranial capacity (CC) is normal or decreased. There is demonstrated an occipital over-rotation of the skull.     

Monitoring of brain-stem trigeminal evoked potentials. Clinical applications in posterior fossa surgery

Brain-stem trigeminal evoked potentials (BTEPs) were monitored intraoperatively in 17 patients during posterior fossa surgery. Satisfactory BTEP recording was performed in all patients without technical problems or interfering with the activity of the operating team. The BTEP was not altered by anesthetic agents or muscle relaxants. Intraoperative monitoring of the BTEP showed wave form alterations or increasing peak latencies in 10 patients. Among these patients, the BTEP demonstrated a dynamic correlation with the surgical process in 8 instances. Two major causative surgical manipulations were identified: cerebellar retraction in 4 cases and tumor dissection from the brain-stem in 6 cases. Withholding the dissection of the tumor, readjusting a cerebellar retractor or further modifying the surgical attitude resulted in partial or complete return of the wave form in 7 patients. The BTEP at the end of surgery proved to correlate with the immediate surgical outcome in most instances. We concluded that the intraoperative monitoring of the BTEP was feasible and suggested, despite the small number of patients, a potential value in the survey of brain-stem functions during posterior fossa surgery.     

Inferior Cerebellar Hypoplasia Resembling a Dandy-Walker-Like Malformation in Purebred Eurasier Dogs with Familial Non-Progressive Ataxia: A Retrospective and Prospective Clinical Cohort Study

Cerebellar malformations can be inherited or caused by insults during cerebellar development. To date, only sporadic cases of cerebellar malformations have been reported in dogs, and the genetic background has remained obscure. Therefore, this study`s objective was to describe the clinical characteristics, imaging features and pedigree data of a familial cerebellar hypoplasia in purebred Eurasier dogs. A uniform cerebellar malformation characterized by consistent absence of the caudal portions of the cerebellar vermis and, to a lesser degree, the caudal portions of the cerebellar hemispheres in association with large retrocerebellar fluid accumulations was recognized in 14 closely related Eurasier dogs. Hydrocephalus was an additional feature in some dogs. All dogs displayed non-progressive ataxia, which had already been noted when the dogs were 5 – 6 weeks old. The severity of the ataxia varied between dogs, from mild truncal sway, subtle dysmetric gait, dysequilibrium and pelvic limb ataxia to severe cerebellar ataxia in puppies and episodic falling or rolling. Follow-up examinations in adult dogs showed improvement of the cerebellar ataxia and a still absent menace response. Epileptic seizures occurred in some dogs. The association of partial vermis agenesis with an enlarged fourth ventricle and an enlarged caudal (posterior) fossa resembled a Dandy-Walker-like malformation in some dogs. Pedigree analyses were consistent with autosomal recessive inheritance.     

中国更新世兔属化石两新种

中国更新世兔属(Lepus)化石较为丰富,尤其是周口店各化石地点产出了大量的标本。但受条件的限制,缺乏对现生骨骼标本的研究与对比,分类位置混乱或仅鉴定为未定种。详细观察研究了中国科学院动物研究所保存的现生兔属8种的187件头骨标本,归纳整理出Lepus各个种头骨与牙齿特征的个体差异和年龄变化以及稳定的特征。主要稳定特征包括:鼻骨基本形态,如长度、前后相对宽度等;额骨两侧凹陷深浅;眶上突上翘程度;颞窝的深浅及宽度;成年个体上间顶骨愈合,或不完全愈合;门齿前齿沟的形态及白垩质充填的情况;门齿孔宽,腭桥长及翼内窝宽度的比例关系;颧骨高度,浅层咬肌窝及咬肌突腹面三角的形态(反映出咬肌的发育程度);吻部形态;下颌骨基本形态(冠状突、上升支、齿隙骨体、颏孔位置等);颊齿基本形态等。在对现生标本观察研究的基础上,详细描述了周口店第13地点的兔头骨及颅后骨骼,命名一新种德氏兔Lepus teilhardisp. nov.。新种以下列特征区别于已知兔属各种:颅全长平均大于90 mm,眶上突轻微上翘,前支稍短,后支发育;额骨两侧凹陷浅;咬肌突腹面中等大小;颧弓浅层咬肌窝较深;翼内窝宽度明显大于腭桥最小纵径;门齿孔较细长;颞窝上突起较高;枕外结节向下延伸成一低脊;听泡较大;外枕骨较宽,顶视几乎覆盖岩乳骨及部分听泡;I2前齿沟"V"字形,内、外两侧的前缘较平直且几乎持平,充填少量白垩质;下颌骨冠状突倾斜。陕西蓝田陈家窝子发现的翁氏兔(Lepus wongi)也归入该种内。将山东淄博孙家山发现的标本命名为淄博兔Lepus ziboensissp. nov.。该种门齿前齿沟浅窄,充填白垩质;齿隙明显较长;腭桥较长;翼内窝宽度与腭桥长度近乎相等;P2外前褶沟窄浅,内前褶沟亦较浅;p3在1件标本上可见较浅的前内褶沟。根据共生动物群分析,淄博兔的时代为早更新世晚期,参照测年数据德氏兔的时代可能从早更新世晚期至中更新世早期。     

Thermal stress markers in <Emphasis Type="Italic">Colpophyllia</Emphasis><Emphasis Type="Italic">natans</Emphasis> provide an archive of site-specific bleaching events

Tropical coral reef monitoring relies heavily on in situ diver observations. However, in many reef regions resources are not available to regularly monitor reefs. This lack of historical baseline data makes it difficult to determine how different reefs respond to environmental stressors and what the implications are for management. To test whether coral cores could be used to identify bleaching events retrospectively, three sites in Tobago with pre-existing reef data including water quality and bleaching observations were identified. Colpophyllia natans cores were examined for growth anomalies which occurred during periods of thermal stress. If present, anomalies were compared to in situ, real-time bleaching observations and water quality data. Interestingly, sites with better water quality during the 2005 thermal anomaly were less prone to bleaching. We suggest that by reducing terrestrial run-off (e.g., sediment and nutrients), and therefore improving marine water quality, reef managers could enhance near-shore coral reef resilience during high-temperature events.     

颅底脊索瘤的影像学诊断及治疗研究(附26例报告)(英文)

目的:探讨颅底脊索瘤的CT、MRI表现及治疗措施。方法:回顾性分析经病理证实的26例脊索瘤患者的临床资料。肿瘤位于鞍区及鼻咽部者9例,位于中颅窝者5例,位于后颅窝者8例,混合型4例。手术入路:额颞入路-翼点开颅9例,鼻内镜下经蝶入路5例,颞下、颞枕及扩大中颅窝入路8例,4例未手术行放射治疗。结果:肿瘤全切8例,大部及次全切14例,围手术期未见死亡病例。25例患者获得随访;3例于术后1年内复发,其中2例死亡,余者颅神经损伤及肢体症状均有改善。结论:脊索瘤无典型临床表现,现多可通过术前影像学检查得以诊断,少数位于特殊位置者需与垂体瘤,颅咽管瘤,三叉神经鞘瘤等鉴别;肿瘤全切较为困难,根据需要选择相应的手术入路可明显提高手术效果;放疗可作为术后辅助治疗。     

Neuroanatomy in fragile X females: the posterior fossa.

The relative homogeneity of the neuropsychiatric phenotype in individuals with fragile (fra) X syndrome suggests that there are consistent central nervous system (CNS) abnormalities underlying the observed cognitive and behavioral abnormalities. In this study, the neuroanatomy of the posterior fossa and other selected CNS regions in 12 young fra X females were compared with those of a group of 12 age-, sex-, and IQ-matched females without evidence of the fra X syndrome. Fra X females were shown to have decreased size of the posterior cerebellar vermis and increased size of the fourth ventricle, findings that are identical to those previously reported for fra X males. When compared with fra X male and nonfra X control groups, the distribution of the posterior-vermis and fourth-ventricle variables for the fra X female group was intermediate. These results support the hypothesis that the fra X genetic abnormality leads to hypoplasia of the posterior cerebellar vermis, a neuroanatomical variation of potential importance to both developmental and neuropsychiatric syndromes.     

Meiotic abnormalities in infertile males

Meiotic anomalies, as reviewed here, are synaptic chromosome abnormalities, limited to germ cells that cannot be detected through the study of the karyotype. Although the importance of synaptic errors has been underestimated for many years, their presence is related to many cases of human male infertility. Synaptic anomalies can be studied by immunostaining of synaptonemal complexes (SCs), but in this case their frequency is probably underestimated due to the phenomenon of synaptic adjustment. They can also be studied in classic meiotic preparations, which, from a clinical point of view, is still the best approach, especially if multiplex fluorescence in situ hybridization is at hand to solve difficult cases. Sperm chromosome FISH studies also provide indirect evidence of their presence. Synaptic anomalies can affect the rate of recombination of all bivalents, produce achiasmate small univalents, partially achiasmate medium-sized or large bivalents, or affect all bivalents in the cell. The frequency is variable, interindividually and intraindividually. The baseline incidence of synaptic anomalies is 6-8%, which may be increased to 17.6% in males with a severe oligozoospermia, and to 27% in normozoospermic males with one or more previous IVF failures. The clinical consequences are the production of abnormal spermatozoa that will produce a higher number of chromosomally abnormal embryos. The indications for a meiotic study in testicular biopsy are provided.     

Severe alterations of cerebellar cortical development after constitutive activation of Wnt signaling in granule neuron precursors

The Wnt/β-catenin signaling pathway plays crucial roles in early hindbrain formation, and its constitutive activity is associated with a subset of human medulloblastoma, a malignant childhood tumor of the posterior fossa. However, the precise function of Wnt/β-catenin signaling during cerebellar development is still elusive. We generated Math1-cre::Apc(Fl/Fl) mice with a conditional knockout for the Adenomatosis polyposis coli (Apc) gene that displayed a constitutive activity of Wnt/β-catenin signaling in cerebellar granule neuron precursors. Such mice showed normal survival without any tumor formation but had a significantly smaller cerebellum with a complete disruption of its cortical histoarchitecture. The activation of the Wnt/β-catenin signaling pathway resulted in a severely inhibited proliferation and premature differentiation of cerebellar granule neuron precursors in vitro and in vivo. Mutant mice hardly developed an internal granular layer, and layering of Purkinje neurons was disorganized. Clinically, these mice presented with significantly impaired motor coordination and ataxia. In summary, we conclude that cerebellar granule neurons essentially require appropriate levels of Wnt signaling to balance their proliferation and differentiation.     

Endocrine Dysfunction in A Patient with Phace Syndrome,Including Port-Wine Stain of the Right Periorbital Area

ObjectiveTo report a case of PHACE syndrome— Posterior fossa brain abnormalities, Hemangioma (usually facial), Arterial anomalies, Coarctation of the aorta along with cardiac defects, and Eye abnormalities—in a 16-yearold female patient with a port-wine stain of the right periorbital area present since birth in conjunction with hypoplasia of the contralateral internal carotid artery.MethodsThyroid-stimulating hormone, free thyroxine, and growth hormone (GH) levels were measured, and insulin-induced hypoglycemia and arginine infusion tests were done. Radiologic investigations included sagittal enhanced T1-weighted magnetic resonance imaging of the brain and the pituitary gland as well as computed tomography and magnetic resonance angiography of the head and neck.ResultsThe patient had a normal karyotype. Her height and weight were below the 5th percentile for her chronologic age, and she had amenorrhea. Laboratory investigations revealed both thyroid and GH deficiencies and confirmed the diagnosis of hypogonadotropic hypogonadism. The imaging studies showed a right intraorbital hemangioma as well as an enhancing mass in the right internal auditory canal at the cerebellopontine angle, consistent with a posterior fossa hemangioma. Initiation of both thyroid and GH replacement therapy improved her growth rate and yielded a good clinical outcome.ConclusionIn patients with facial or neck hemangiomas, PHACE syndrome should be suspected, and brain imaging and cardiac, ophthalmologic, and endocrinologic evaluations are recommended to screen for other potential PHACE abnormalities. (Endocr Pract. 2010;16:255-259)     

Smoothened and ARL13B are critical in mouse for superior cerebellar peduncle targeting

Patients with the ciliopathy Joubert syndrome present with physical anomalies, intellectual disability, and a hindbrain malformation described as the “molar tooth sign” due to its appearance on an MRI. This radiological abnormality results from a combination of hypoplasia of the cerebellar vermis and inappropriate targeting of the white matter tracts of the superior cerebellar peduncles. ARL13B is a cilia-enriched regulatory GTPase established to regulate cell fate, cell proliferation, and axon guidance through vertebrate Hedgehog signaling. In patients, mutations in ARL13B cause Joubert syndrome. To understand the etiology of the molar tooth sign, we used mouse models to investigate the role of ARL13B during cerebellar development. We found that ARL13B regulates superior cerebellar peduncle targeting and these fiber tracts require Hedgehog signaling for proper guidance. However, in mouse, the Joubert-causing R79Q mutation in ARL13B does not disrupt Hedgehog signaling nor does it impact tract targeting. We found a small cerebellar vermis in mice lacking ARL13B function but no cerebellar vermis hypoplasia in mice expressing the Joubert-causing R79Q mutation. In addition, mice expressing a cilia-excluded variant of ARL13B that transduces Hedgehog normally showed normal tract targeting and vermis width. Taken together, our data indicate that ARL13B is critical for the control of cerebellar vermis width as well as superior cerebellar peduncle axon guidance, likely via Hedgehog signaling. Thus, our work highlights the complexity of ARL13B in molar tooth sign etiology.     

Posterior Fossa Decompression Combined with Resection of the Cerebellomedullary Fissure Membrane and Expansile Duraplasty: A Radical and Rational Surgical Treatment for Arnold–Chiari Type I Malformation

This study aims to introduce a new surgical procedure for the treatment of Arnold–Chiari type I malformation (ACM-1) and to compare its effectiveness with the techniques described in previous studies. We performed the following procedures: foramen magnum decompression combined with the removal of both the atlanto-occipital membrane, extended resection of the cerebellomedullary fissure arachnoid membrane, and artificial duraplasty to enlarge the membranic posterior fossa without resecting the cerebellar tonsils and syringosubarachnoid shunting. There were 21 ACM-1 patients: 12 cases had osteo-compression on the cerebellar hemisphere, 18 cases had thickened adhered fabric ring that stretched from arachnoid membrane to cerebellar hemisphere, and 15 cases with syringomyelia. The patients were followed up for 6 months to 3 years after the surgery. All patients showed a remarkable recovery of syringomyelia. There were no morbidity or death related to the surgery. Most of ACM-1 patients, the osteo- and membrane compression on cerebellar hemisphere and tonsil were observed during the operation. Therefore, decompression of foramen magnum and posterior craniocervical combined with the removal of cerebellomedullary fissure arachnoid membrane and placement of an artificial dural graft should be considered as a comprehensive option of minimally invasive surgery and rational and radical treatment of ACM-1. Our experience showed that, by using our procedure, shunting becomes no longer necessary in the treatment of ACM-1-associated syringomyelia.     

Coexistance of cerebral sinovenous thrombosis and Dandy Walker malformation in newborn

Cerebral sinovenous thrombosis in neonatal period may cause neurological impairment, epilepsy, and lead to stroke. It is caused primarily by coagulopathy of numerous reasons, occasionally perinatal asphyxia, traumatic delivery and hyperhomocysteinemia. Dandy-Walker malformation is characterized by agenesis or hypoplasia of the cerebellar vermis, cystic dilatation of the fourth ventricle, and enlargement of the posterior fossa. Dandy-Walker malformation, variant, and mega cisterna magna represent a spectrum of developmental anomalies. Insults to developing cerebellar hemispheres and the fourth ventricle are believed to be the cause of malformation. Our patient was born from noncomplicated pregnancy, noncomplicated nontraumatic vaginal delivery at term, excellent Apgar scores, without peculiarities in clinical status. She was brest-fed by the 42nd hour of life when she had rightsided seizures during sleep that repeated for five times in next 24 hours. Brain Ultrasound (US) revealed clot in left lateral ventricle, slight dilatation of left ventricle, both sided periventricular echodensity, ischemia, slight enlargement of forth ventricle and a bit smaller cerebellum. There was no visible flow through left transverse, superior sagittal and straight sinus. Magnetic Resonance (MRI) confirmed the finding and showed thrombosis of left and right transverse venous sinuses and confluence of sinuses. Electroencephalogram (EEG) showed leftsided focal changes. The newborn was treated with phenobarbiton for 8 days and had no convulsions during that period. All coagulation parameters, homocistein, lipoproteins (a) and D-dimers were normal. There were no mutations on FV R506Q, PT 20210A, MTHFR 677C/T. No antiphospholipides were found. Heart US showed no structural anomalies. No other patology or risk factors were present at the time. Before discharge, US showed hydrocephalus. Flow in affected sinuses was visible with color Doppler. MRI showed recanalization of affected sinuses, also hydrocephalus and presentation of Dandy Walker On EEG there was borderline finding. Due to progression of hydrocephalus ventriculo-peritoneal shunt was placed. In age of 1 year EEG was slower for age but without focus. Neurological development was normal for age. The question is whether this child had intrauterine insult and inception of Dandy Walker with further postnatal progress of thrombosis and evolution to full picture of Dandy Walker with hydrocephalus OR thrombosis that led to development of hydrocephalus and Dandy Walker malformation in this child were accidental coexistance.     

Studying metabolic regulation in human muscle

Phosphorus magnetic resonance spectroscopy, despite some limitations, is a valuable non-invasive window on muscle metabolism in vivo, particularly oxidative ATP synthesis. A number of experiments have shown this to be dominated by closed-loop feedback mechanisms: a well-known model posits regulation by ADP, but there are others, difficult to distinguish experimentally. Moreover the contribution of open-loop control mechanisms ('feed forward' or 'parallel activation') in vivo remains controversial. Progress will require more precise data, better integrated with other measurements (e.g. muscle oxygenation), and improvement of the conceptual tools appropriate to such studies, where data are limited and steady-state assumptions frequently inapplicable.     

Characterization of familial partial 10p trisomy by chromosomal microdissection,FISH, and microsatellite dosage analysis

Unbalanced translocations are a frequent cause of multiple congenital anomalies in children. Translocations as small as 2–5 Mb of DNA are detectable by G-banding under optimal conditions. Some of these small translocations are visible but cannot be characterized cytogenetically due to the lack of characteristic banding on Giemsa preparations. We have combined chromosomal microdissection and fluorescence in situ hybridization (FISH) to identify the origin of a small translocated segment in three members of a family with a derivative chromosome 9 and multiple anomalies, including several ophthalmologic anomalies. We microdissected the abnormal region of the derivative 9 chromosome and used this DNA to generate a FISH probe. This probe hybridized to distal 10p on the metaphase spread of the proband, indicating the origin of the translocated segment. A whole 10p FISH probe confirmed the origin by hybridizing to the translocated segment of the derivative chromosome. FISH was then performed with a whole chromosome 9 painting probe and excluded the presence of a reciprocal, balancing translocation. We then studied the chromosome 10 partial duplication with microsatellite markers to better characterize the chromosomal segment that caused these phenotypic features. By examining the involved areas with distal 10p and 9p microsatellite markers, we were able to demonstrate a minimum of 9 Mb of trisomic 10p DNA with a chromosomal breakpoint between 10p14– 10p15. We then compared this family’s clinical findings to those of individuals with partial 10p trisomy who had been reported in the literature. The clinical phenotypes seen in this family are similar to, but milder than, the phenotypes of persons with the larger partial trisomies of 10p that were diagnosable by cytogenetic analysis alone. This study shows that microdissection and DNA markers can be used to precisely define small translocations that are difficult to identify by conventional G-banded chromosome analysis. Received: 29 February 1996 / Revised: 19 April 1996