Symptomatic spinal arachnoid cyst with spastic diplegia secondary to cerebral palsy: illustrative case.

BACKGROUND: Selective dorsal rhizotomy (SDR) can improve the spastic gait of carefully selected patients with cerebral palsy. Spinal arachnoid cysts are a rare pathology that can also cause spastic gait secondary to spinal cord compression. OBSERVATIONS: The authors present an interesting case of a child with cerebral palsy and spastic diplegia. He was evaluated by a multidisciplinary team and determined to be a good candidate for SDR. Preoperative evaluation included magnetic resonance imaging (MRI) of the spine, which identified an arachnoid cyst causing spinal cord compression. The cyst was surgically fenestrated, which provided some gait improvement. After recovering from cyst fenestration surgery, the patient underwent SDR providing further gait improvement. LESSONS: SDR can be beneficial for some patients with spastic diplegia. Most guidelines do not include spinal MRI in the preoperative evaluation for SDR. However, spinal MRI can be beneficial for surgical planning by localizing the level of the conus. It may also identify additional spinal pathology that is contributing to the patient's spasticity. In rare cases, such as this one, patients may benefit from staged surgery to address structural causes of spastic gait prior to proceeding with SDR.

First-time tethered cord release among adults with myelomeningocele: an analysis of people in the National Spina Bifida Patient Registry.

OBJECTIVE: The authors analyzed the National Spina Bifida Patient Registry (NSBPR), a national registry that tracks the outcomes for people with various forms of spinal dysraphism, to determine the ongoing longitudinal risk for tethered cord release (TCR) among adults with myelomeningocele who had not previously undergone TCR during childhood. The authors also sought to identify the impact of lesion level, ambulation status, and prior treatments for hydrocephalus or Chiari malformations on TCR rates. METHODS: Adults in the registry who had not previously undergone TCR during childhood were studied. This group was compared with the remaining adults in the registry. The frequency of first-time TCR and time to TCR (using Kaplan-Meier analysis) were determined independently for males and females. Cox proportional hazards analysis identified correlations between sex, best lesion level and ambulation status prior to TCR, and previous treatments for hydrocephalus and Chiari decompression. RESULTS: Among 967 adults in the NSBPR (422 [43.6%] males and 545 [56.4%] females) who had not undergone TCR during childhood, the authors identified 47 people (4.9%) who underwent their first TCR during adulthood. This study cohort had significantly better mean functional motor levels and ambulation compared with the remaining adult cohort (both p < 0.001). The study group included 35 females (74.5%) and 12 males (25.5%); this sex distribution was significantly different in comparison with the remaining adult cohort (p = 0.016). The Kaplan-Meier curves for first TCR for females and males were significantly different (p = 0.01, log-rank test). TCR rates were correlated with sex (males had decreased risk; OR 0.31, 95% CI 0.16-0.62, p < 0.001), prior treatment for hydrocephalus (those who underwent prior treatment had decreased risk; OR 0.21, 95% CI 0.20-0.42, p < 0.001), and prior treatment for Chiari malformation (those who underwent prior treatment had greater risk; OR 3.84, 95% CI 1.50-9.88, p = 0.005). CONCLUSIONS: Adults with myelomeningocele who escape childhood without undergoing TCR have an ongoing, albeit decreased, risk for spinal cord tethering requiring TCR. This risk is obviously not due to spinal column growth and therefore must reflect other factors such as dynamic changes in spinal cord health over time. Among people with MMC who underwent their first TCR as adults, females seemed to be overrepresented. Similar to the authors' prior childhood study, people who underwent previous Chiari decompression seemed to be overrepresented, whereas those who underwent previous treatment for hydrocephalus seem to be underrepresented. These novel findings deserve further study.

Significant brainstem dysfunction in neonates with myelomeningoceles: a comparison of prenatal versus postnatal closure.

OBJECTIVE: The purpose of this study was to compare the incidence of significant brainstem dysfunction (SBD) in neonates with myelomeningocele who have been treated with prenatal versus postnatal closure at a single institution. METHODS: The records and imaging of all children undergoing either prenatal (n = 27) or postnatal (n = 60) closure of myelomeningocele at the authors' institution from December 2014 through May 2021 were reviewed. SBD, fetal ventricular size, gestational age at fetal imaging and delivery, postnatal ventricular size, need for and type of hydrocephalus treatment, spinal neurological level at birth, anatomical Chiari severity, death, and prenatal or postnatal repair were factors recorded. SBD was defined by need for airway surgery or gastrostomy tube, or endotracheal intubation because of apnea, aspiration, or airway control problems. Comparisons between prenatal and postnatal cohorts and between the cohorts with and without SBD were performed. RESULTS: SBD occurred in 25% and 0% of neonates who underwent postnatal and prenatal closure, respectively. There were no differences in fetal ventricular size or spinal neurological level between the prenatal and postnatal cohorts or between those with or without SBD. Anatomical severity of the Chiari malformation after birth was worse in the postnatal cohort. Hydrocephalus treatment was required in 70% and 33% of infants who underwent postnatal and prenatal closure, respectively. All three deaths were in the postnatal group from SBD. CONCLUSIONS: Prenatal closure of myelomeningocele is associated with a significant reduction in SBD.

Estimating the prevalence of neurosurgical interventions in adults with spina bifida using the Health Facts data set: implications for transition planning and the development of adult clinics.

OBJECTIVE: As the care of patients with spina bifida continues to evolve, life expectancy is increasing, leading to a critical need for transition planning from pediatric-based to adult-based care. The burden of neurosurgical care for adults with spina bifida remains unknown. In this study, the authors sought to use a large national data set to estimate the prevalence of neurosurgical interventions in adults with spina bifida. METHODS: This study utilized Health Facts, which is a de-identified proprietary data set abstracted from all Cerner electronic health records. It includes 69 million unique patients with > 500 million encounters in 580 centers. Validation, technical exclusions, and data filters were applied to obtain an appropriate cohort of patients. The ICD-9 and ICD-10 codes for all types of spinal dysraphism, as well as the Current Procedural Terminology (CPT) codes for hydrocephalus procedures, spinal cord untethering, and Chiari decompression, were queried and records were retrieved. Demographic variables along with differences in age groups and temporal trends were analyzed. RESULTS: Overall, 24,764 unique patients with ≥ 1 encounter with a spinal dysraphism diagnosis between 2000 and 2017 were identified. The pediatric cohort included 11,123 patients with 60,027 separate encounters, and the adult cohort included 13,641 patients with 41,618 separate encounters. The proportion of females was higher in the adult (62.9%) than in the pediatric (51.4%) cohort. Annual encounters were stable from 2 to 18 years of age, but then decreased by approximately half with a precipitous drop after age 21 years. The sex distribution of adults and children who underwent procedures was similar (54.6% female adults vs 52.4% female children). Surgical interventions in adults were common. Between 2013 and 2017, there were 4913 procedures for hydrocephalus, with 2435 (49.6%) adult patients. Similarly, 273 (33.3%) of the 819 tethered cord procedures were performed in adults, as were 307 (32.9%) of 933 Chiari decompressions. CONCLUSIONS: The Health Facts database offered another option for studying care delivery and utilization in patients aging with spina bifida. The median age of this population has now reached early adulthood, and a significant number of neurosurgical procedures were performed in adults. An abrupt drop in the rate of encounters occurred at 21 years of age, possibly reflecting transition issues such as access-to-care problems and lack of coordinated care.

Expression of and correlational patterns among neuroinflammatory, neuropeptide, and neuroendocrine molecules from cerebrospinal fluid in cerebral palsy.

BACKGROUND: The underlying pathogenesis of cerebral palsy (CP) remains poorly understood. The possibility of an early inflammatory response after acute insult is of increasing interest. Patterns of inflammatory and related biomarkers are emerging as potential early diagnostic markers for understanding the etiologic diversity of CP. Their presence has been investigated in plasma and umbilical cord blood but not in cerebrospinal fluid (CSF). METHODS: A clinical CP sample was recruited using a single-time point cross-sectional design to collect CSF at point-of-care during a standard-of-care surgical procedure (intrathecal pump implant). Patient demographic and clinical characteristics were sourced from medical chart audit. RESULTS: Significant (p ≤ 0.001) associations were found among neuroinflammatory, neuroendocrine, and nociceptive analytes with association patterns varying by birth status (term, preterm, extremely preterm). When between birth-group correlations were compared directly, there was a significant difference between preterm and extremely preterm birth subgroups for the correlation between tumour necrosis factor alpha (TNFα) and substance P. CONCLUSION: This investigation shows that CSF can be used to study proteins in CP patients. Differences in inter-correlational patterns among analytes varying by birth status underscores the importance of considering birth status in relation to possible mechanistic differences as indicated by biomarker signatures. Future work should be oriented toward prognostic and predictive validity to continue to parse the heterogeneity of CP's presentation, pathophysiology, and response to treatment.

Tethered spinal cord among individuals with myelomeningocele: an analysis of the National Spina Bifida Patient Registry.

OBJECTIVE: The aims of this study were to review the National Spina Bifida Patient Registry (NSBPR) data set to study the rates of tethered spinal cord release (TCR) among patients with myelomeningocele and variability between centers, to compare TCR rates between males and females, and to study the relationships between TCR rates and other condition-specific characteristics. METHODS: The NSBPR registry was queried to identify all patients with myelomeningocele. TCR rates were calculated over time using survival analyses; rates between centers and between males and females were compared. Cox proportional hazards models were constructed to identify relationships between TCR rates and sex, functional lesion level, ambulation status, treated hydrocephalus, and prior Chiari decompression. RESULTS: Of 6339 patients with information about their operations, 1366 (21.5%) underwent TCR, with significant variability between centers. The majority (75.8%) underwent a single TCR. The annual TCR rate was linear between birth and 13 years (1.8%/year) but declined sharply from 14 to 21 years (0.7%/year). There was no period of time at which the TCR rate accelerated. There were no significant differences in TCR rates between males and females. TCR rate was not related to functional lesion level but was lower among nonambulators compared with community ambulators (p = 0.005) and among those with treated hydrocephalus (HR 0.30, p < 0.001), and higher among those having prior Chiari decompression (HR 1.71, p < 0.001). CONCLUSIONS: These results extend the results of prior single-institution studies, demonstrate significant treatment variability between institutions, and challenge the traditional concept that tethering is related to spinal cord stretching due to spinal growth.

Intrathoracic migration of ventriculo-peritoneal shunt via Morgagni hernia.

We present the case of a 5-month-old patient presenting with pleural migration of ventriculo-peritoneal shunt catheter who returned 2 months later with respiratory distress. Ultimately, the diagnosis of a Morgagni hernia was made. This diagnosis, though rare, should be entertained in certain clinical settings.

Neurosurgery guidelines for the care of people with spina bifida.

Myelomeningocele (MMC) arises from an early neural developmental anomaly and results in a variety of structural abnormalities and associated functional neurologic deficits. As such, neurologic issues are central to virtually all clinical problems. Neurosurgical intervention strives to correct or improve these defects and prevent secondary complications. These interventions include closure of the open myelomeningocele and management (across the life span) of hydrocephalus, the Chiari II malformation (C2M) and tethered spinal cord (TSC). The development of pre-natal closure techniques and reports of improved outcome with in-utero closure (IUMC) have revolutionized the neurosurgical approach to myelomeningocele. Controversies remain surrounding patient selection, maternal risks, technique of IUMC (endoscopic vs. open) and long-term outcomes. However, real gains include reduced rates of hydrocephalus, modestly improved motor capabilities and reduction in C2M morbidity. For many decades, the cornerstone of treatment of hydrocephalus for many decades has been the placement and support of ventricular shunts. Endoscopic third ventriculostomy (ETV) with or without choroid plexus coagulation (ETV/CPC) is an appealing alternate strategy that avoids the morbidity and complications associated with shunts. The exact criteria for ETV-CPC candidacy and best metrics for outcome analysis remain active areas of debate and controversy. Similarly, neurosurgical management C2M, has centered upon the indications and clinical thresholds for performing posterior fossa surgical decompression. Tethered spinal cord management incorporates the diagnosis and surgical management of adhesions formed at the initial closure site, the consequent longitudinal traction related stress on the cord and the resulting neurologic signs and symptoms.

Musculoskeletal Pain Outcomes Pre- and Post Intrathecal Baclofen Pump Implant in Children With Cerebral Palsy: A Prospective Cohort Study.

OBJECTIVE: To characterize musculoskeletal pain intensity, duration, frequency, and interference with activities of daily living in children with cerebral palsy (CP) before and after intrathecal baclofen pump placement. DESIGN: Prospective cohort study. SETTING: Children's tertiary hospital. PARTICIPANTS: Participants were children with CP (N=32; 53% male; mean age, 9.9y; age range, 4-17y). The majority of participants had a CP diagnosis of quadriplegia (76%) and relied on wheeled mobility (91%). INTERVENTIONS: Assessments were completed pre- and post intrathecal baclofen pump implant. MAIN OUTCOME MEASURES: Because of considerable patient heterogeneity, both pain measures (Brief Pain Inventory, Dalhousie Pain Interview) were completed by proxy (parent) report at the time of the procedure and approximately 6 months after intrathecal baclofen (ITB) pump placement. RESULTS: Prior to implant, 31% of participants were living with constant pain, which reduced to 6% post ITB implant (P<.001). Based on Wilcoxon signed rank tests, pain duration significantly decreased post ITB pump implant (P<.01). CONCLUSIONS: This prospective analysis supports the anecdotal and retrospective evidence that musculoskeletal pain decreases in CP following ITB pump implant. The greatest effect appears to be on the duration of pain experience. Pain did not decrease for all individuals, and it would be worth further investigation to better understand the relation between patient characteristics and pain outcomes.

Intracranial subdural empyemas and epidural abscesses in children

OBJECTIVE: The authors conducted a retrospective analysis of a consecutive series of children with intracranial subdural empyemas (SEs) and epidural abscesses (EAs) to highlight the important clinical difference between these two entities. They describe the delays and pitfalls in achieving accurate diagnoses and make treatment recommendations based on clinical and imaging findings. METHODS: They reviewed their experience with children who had presented with intracranial SE and/or EA in the period from January 2013 to May 2018. They recorded presenting complaint, date of presentation, age, neurological examination findings, time from presentation to diagnosis, any errors in initial image interpretation, timing from diagnosis to surgical intervention, type of surgical intervention, neurological outcome, and microbiology data. They aimed to assess possible causes of any delay in diagnosis or surgical intervention. RESULTS: Sixteen children with SE and/or EA had undergone evaluation by the authors' neurosurgical service since 2013. Children with SE (n = 14) presented with unmistakable evidence of CNS involvement with only one exception. Children with EA alone (n = 2) had no evidence of CNS dysfunction. All children older than 1 year of age had sinusitis. The time from initial presentation to a physician to diagnosis ranged from 0 to 21 days with a mean and median of 4.5 and 6 days, respectively. The time from diagnosis to neurosurgical intervention ranged from 0 to 14 days with a mean and median of 3 and 1 day, respectively. Delay in treatment was due to misinterpretation of images, a failure to perform timely imaging, progression on imaging as an indication for surgical intervention, or the managing clinician's preference. Among the 14 cases with SE, initial imaging studies in 6 were not interpreted as showing SE. Four SE collections were dictated as epidural even on MRI. The only fatality was associated with no surgical intervention. Endoscopic sinus surgery was not associated with reducing the need for repeat craniotomy. CONCLUSIONS: Regardless of the initial imaging interpretation, any child presenting with focal neurological deficit or seizures and sinusitis should be assumed to have an SE or meningitis, and a careful review of high-resolution imaging, ideally MRI with contrast, should be performed. If an extraaxial collection is identified, surgical drainage should be performed expeditiously. Neurosurgical involvement and evaluation are imperative to achieve timely diagnoses and to guide management in these critically ill children. ABBREVIATIONS: EA = epidural abscess; SE = subdural empyema.

Retinal Findings in Young Children With Increased Intracranial Pressure From Nontraumatic Causes.

OBJECTIVES: Increased intracranial pressure (ICP) has been suggested in legal settings as an alternative cause of retinal hemorrhages (RHs) in young children who may have sustained abusive head trauma. We assessed the prevalence and characteristics of RHs in children with increased ICP. METHODS: We conducted a prospective, multicenter study of children <4 years old with newly diagnosed increased ICP as determined by using direct measurement and/or clinical criteria. Infants who were premature, neonates, and suspected survivors of abusive head trauma were excluded on the basis of nonocular findings. Fundus examinations were performed; extent, number, and type of RH in each of 4 distinct retinal zones were recorded. RESULTS: Fifty-six children (27 boys) were studied (mean age 15.4 months; range 1-43 months). All of the children had elevated ICP that required intervention. One child had papilledema. No child (0%; 95% confidence interval: 0%-6.4%) or eye (0%; 95% confidence interval: 0%-3.3%) was found to have an RH. Causes of increased ICP included hydrocephalus, intraventricular hemorrhage, congenital malformations, malfunctioning shunts, and the presence of intracranial space-occupying lesions. CONCLUSIONS: Although acute increased ICP can present in children with a pattern of peripapillary superficial RHs in the presence of papilledema, our study supports the conclusion that RHs rarely occur in the absence of optic disc swelling and do not present beyond the peripapillary area in the entities we have studied.

Treated hydrocephalus in individuals with myelomeningocele in the National Spina Bifida Patient Registry.

OBJECTIVEAlthough the majority of patients with myelomeningocele have hydrocephalus, reported rates of hydrocephalus treatment vary widely. The purpose of this study was to determine the rate of surgical treatment for hydrocephalus in patients with myelomeningocele in the National Spina Bifida Patient Registry (NSBPR). In addition, the authors explored the variation in shunting rates across NSBPR institutions, examined the relationship between hydrocephalus, and the functional lesion level of the myelomeningocele, and evaluated for temporal trends in rates of treated hydrocephalus.METHODSThe authors queried the NSBPR to identify all patients with myelomeningoceles. Individuals were identified as having been treated for hydrocephalus if they had undergone at least 1 hydrocephalus-related operation. For each participating NSBPR institution, the authors calculated the proportion of patients with treated hydrocephalus who were enrolled at that site. Logistic regression was performed to analyze the relationship between hydrocephalus and the functional lesion level of the myelomeningocele and to compare the rate of treated hydrocephalus in children born before 2005 with those born in 2005 or later.RESULTSA total of 4448 patients with myelomeningocele were identified from 26 institutions, of whom 3558 patients (79.99%) had undergone at least 1 hydrocephalus-related operation. The rate of treated hydrocephalus ranged from 72% to 96% among institutions enrolling more than 10 patients. This difference in treatment rates between centers was statistically significant (p < 0.001). Insufficient data were available in the NSBPR to analyze reasons for the different rates of hydrocephalus treatment between sites. Multivariate logistic regression demonstrated that more rostral functional lesion levels were associated with higher rates of treated hydrocephalus (p < 0.001) but demonstrated no significant difference in hydrocephalus treatment rates between children born before versus after 2005.CONCLUSIONSThe rate of hydrocephalus treatment in patients with myelomeningocele in the NSBPR is 79.99%, which is consistent with the rates in previously published literature. The authors' data demonstrate a clear association between functional lesion level of the myelomeningocele and the need for hydrocephalus treatment.

Decompression for Chiari malformation type II in individuals with myelomeningocele in the National Spina Bifida Patient Registry.

OBJECTIVEThe purpose of this study was to determine the rate of decompression for Chiari malformation type II in individuals with myelomeningocele in the National Spina Bifida Patient Registry (NSBPR). In addition, the authors explored the variation in rates of Chiari II decompression across NSBPR institutions, examined the relationship between Chiari II decompression and functional lesion level of the myelomeningocele, age, and need for tracheostomy, and they evaluated for temporal trends in rates of Chiari II decompression.METHODSThe authors queried the NSBPR to identify all individuals with myelomeningocele between 2009 and 2015. Among these patients, they identified individuals who had undergone at least 1 Chiari II decompression as well as those who had undergone tracheostomy. For each participating NSBPR institution, the authors calculated the proportion of patients enrolled at that site who underwent Chiari II decompression. Logistic regression was performed to analyze the relationship between Chiari II decompression, functional lesion level, age at decompression, and history of tracheostomy.RESULTSOf 4448 individuals with myelomeningocele identified from 26 institutions, 407 (9.15%) had undergone at least 1 Chiari II decompression. Fifty-one patients had undergone tracheostomy. Logistic regression demonstrated a statistically significant relationship between Chiari II decompression and functional lesion level of the myelomeningocele, with a more rostral lesion level associated with a higher likelihood of posterior fossa decompression. Similarly, children born before 2005 and those with history of tracheostomy had a significantly higher likelihood of Chiari II decompression. There was no association between functional lesion level and need for tracheostomy. However, among those children who underwent Chiari II decompression, the likelihood of also undergoing tracheostomy increased significantly with younger age at decompression.CONCLUSIONSThe rate of Chiari II decompression in patients with myelomeningocele in the NSBPR is consistent with that in previously published literature. There is a significant relationship between Chiari II decompression and functional lesion level of the myelomeningocele, which has not previously been reported. Younger children who undergo Chiari II decompression are more likely to have undergone tracheostomy. There appears to be a shift away from Chiari II decompression, as children born before 2005 were more likely to undergo Chiari II decompression than those born in 2005 or later.

Congenital Brain and Spinal Cord Malformations and Their Associated Cutaneous Markers.

The brain, spinal cord, and skin are all derived from the embryonic ectoderm; this common derivation leads to a high association between central nervous system dysraphic malformations and abnormalities of the overlying skin. A myelomeningocele is an obvious open malformation, the identification of which is not usually difficult. However, the relationship between congenital spinal cord malformations and other cutaneous malformations, such as dimples, vascular anomalies (including infantile hemangiomata and other vascular malformations), congenital pigmented nevi or other hamartomata, or midline hairy patches may be less obvious but no less important. Pediatricians should be aware of these associations, recognize the cutaneous markers associated with congenital central nervous system malformations, and refer children with such markers to the appropriate specialist in a timely fashion for further evaluation and treatment.

Neurolysis alone as the treatment for neuroma-in-continuity with more than 50% conduction in infants with upper trunk brachial plexus birth palsy.

OBJECT: The debate addressed in this article is that of surgical treatment methods for a neuroma-in-continuity. The authors of this study chose to test the hypothesis that more severe nerve injuries, as distinguished by < 50% conduction across a neuroma-in-continuity, could be treated with neuroma resection and grafting, whereas less severe nerve injuries, with > 50% conduction across the neuroma, could be treated with neurolysis alone. METHODS: The goal of this study was to compare preoperative and postoperative Active Movement Scale (AMS) scores in children with upper trunk brachial plexus birth injuries treated with neurolysis alone if the neuroma's conductivity was > 50% on intraoperative nerve testing. Seventeen patients (7 male, 10 female) met the criteria for inclusion in this study. Surgery was done when the patients were an average of 10 months old (range 6-19 months). The authors analyzed AMS scores from the preoperative assessment, 1-year postoperative follow-up visit, and subsequent follow-up assessment as close to 3 years after surgery as possible (referred to in this paper as > 2-year postoperative scores). RESULTS: Comparison of preoperative and 1-year follow-up data showed significant improvement in shoulder abduction, flexion, external rotation, and internal rotation; elbow flexion and supination; and wrist extension. Comparison of preoperative findings and results of assessment at > 2-year follow-up showed significant improvement in shoulder abduction, flexion, external rotation; and elbow flexion and supination. At final follow-up, useful function (AMS score of 6 or 7) was achieved for elbow flexion in 14 of 16 patients, shoulder flexion in 11 of 15 patients, shoulder abduction in 11 of 16 patients, and shoulder external rotation in 5 of 15 patients. CONCLUSIONS: This report indicates that there is a subgroup of patients who can benefit clinically, with functional improvement of shoulder and elbow function, from treatment with neurolysis alone for upper trunk lesions demonstrating more than 50% conduction across the neuroma on intraoperative nerve testing. Patients with less than 50% conduction, indicating more severe disease, are treated with nerve resection and grafting in the authors' treatment algorithm.

CASK mutations are frequent in males and cause X-linked nystagmus and variable XLMR phenotypes.

Mutations of the calcium/calmodulin-dependent serine protein kinase (CASK) gene have recently been associated with X-linked mental retardation (XLMR) with microcephaly, optic atrophy and brainstem and cerebellar hypoplasia, as well as with an X-linked syndrome having some FG-like features. Our group has recently identified four male probands from 358 probable XLMR families with missense mutations (p.Y268H, p.P396S, p.D710G and p.W919R) in the CASK gene. Congenital nystagmus, a rare and striking feature, was present in two of these families. We screened a further 45 probands with either nystagmus or microcephaly and mental retardation (MR), and identified two further mutations, a missense mutation (p.Y728C) and a splice mutation (c.2521-2A>T) in two small families with nystagmus and MR. Detailed clinical examinations of all six families, including an ophthalmological review in four families, were undertaken to further characterise the phenotype. We report on the clinical features of 24 individuals, mostly male, from six families with CASK mutations. The phenotype was variable, ranging from non-syndromic mild MR to severe MR associated with microcephaly and dysmorphic facial features. Carrier females were variably affected. Congenital nystagmus was found in members of four of the families. Our findings reinforce the CASK gene as a relatively frequent cause of XLMR in females and males. We further define the phenotypic spectrum and demonstrate that affected males with missense mutations or in-frame deletions in CASK are frequently associated with congenital nystagmus and XLMR, a striking feature not previously reported.

Clinical study of two brothers with a novel 33 bp duplication in the ARX gene.

Pathogenic variations of the ARX (aristaless-related homeobox) gene are associated with marked phenotypic pleiotropy. These phenotypes are X-linked neurological disorders that include brain and genital malformation and non-malformation syndromes. Typically, malformation phenotypes result from pathogenic variations that are predicted to truncate the ARX protein, or alter residues in the highly conserved homeodomain. While non-malformation phenotypes tend to be caused by pathogenic variations that are predicted to expand the first two polyalanine tracts of ARX, or alter residues outside of the homeodomain. The most common pathogenic variation of the ARX gene is a duplication of 24 bp, c.429_452 dup, which leads to an expansion of the second polyalanine tract of the ARX protein from 12 to 20 alanine residues. This pathogenic variation is associated with both sporadic and familial nonsyndromic mental retardation. Syndromic manifestations include mental retardation with hand dystonia (Partington syndrome), infantile spasms (West syndrome) and/or other epileptic seizures. Here, we report on a novel pathogenic variant of a tandem 33 bp duplication that is predicted to result in an expansion of polyalanine tract 2 in two brothers with mental retardation, epilepsy, dystonia, and the novel feature of intermittent hyperventilation. This pathogenic variation is predicted to result in a "non-homogeneous" polyalanine tract expansion that is longer than predicted expansion caused by the common 24 bp duplication. The location of the novel 33 bp duplication in the same region as the common 24 bp duplication supports this region as the ARX variation "hot spot."

Refined mapping of X-linked reticulate pigmentary disorder and sequencing of candidate genes.

X-linked reticulate pigmentary disorder with systemic manifestations in males (PDR) is very rare. Affected males are characterized by cutaneous and visceral symptoms suggestive of abnormally regulated inflammation. A genetic linkage study of a large Canadian kindred previously mapped the PDR gene to a greater than 40 Mb interval of Xp22-p21. The aim of this study was to identify the causative gene for PDR. The Canadian pedigree was expanded and additional PDR families recruited. Genetic linkage was performed using newer microsatellite markers. Positional and functional candidate genes were screened by PCR and sequencing of coding exons in affected males. The location of the PDR gene was narrowed to a approximately 4.9 Mb interval of Xp22.11-p21.3 between markers DXS1052 and DXS1061. All annotated coding exons within this interval were sequenced in one affected male from each of the three multiplex families as well as one singleton, but no causative mutation was identified. Sequencing of other X-linked genes outside of the linked interval also failed to identify the cause of PDR but revealed a novel nonsynonymous cSNP in the GRPR gene in the Maltese population. PDR is most likely due to a mutation within the linked interval not affecting currently annotated coding exons.