Human TUBB3 mutations perturb microtubule dynamics, kinesin interactions, and axon guidance.

We report that eight heterozygous missense mutations in TUBB3, encoding the neuron-specific beta-tubulin isotype III, result in a spectrum of human nervous system disorders that we now call the TUBB3 syndromes. Each mutation causes the ocular motility disorder CFEOM3, whereas some also result in intellectual and behavioral impairments, facial paralysis, and/or later-onset axonal sensorimotor polyneuropathy. Neuroimaging reveals a spectrum of abnormalities including hypoplasia of oculomotor nerves and dysgenesis of the corpus callosum, anterior commissure, and corticospinal tracts. A knock-in disease mouse model reveals axon guidance defects without evidence of cortical cell migration abnormalities. We show that the disease-associated mutations can impair tubulin heterodimer formation in vitro, although folded mutant heterodimers can still polymerize into microtubules. Modeling each mutation in yeast tubulin demonstrates that all alter dynamic instability whereas a subset disrupts the interaction of microtubules with kinesin motors. These findings demonstrate that normal TUBB3 is required for axon guidance and maintenance in mammals.

A recurrent missense variant in the E3 ubiquitin ligase substrate recognition subunit FEM1B causes a rare syndromic neurodevelopmental disorder.

PURPOSE: Fem1 homolog B (FEM1B) acts as a substrate recognition subunit for ubiquitin ligase complexes belonging to the CULLIN 2-based E3 family. Several biological functions have been proposed for FEM1B, including a structurally resolved function as a sensor for redox cell status by controlling mitochondrial activity, but its implication in human disease remains elusive. METHODS: To understand the involvement of FEM1B in human disease, we made use of Matchmaker exchange platforms to identify individuals with de novo variants in FEM1B and performed their clinical evaluation. We performed functional validation using primary neuronal cultures and in utero electroporation assays, as well as experiments on patient's cells. RESULTS: Five individuals with a recurrent de novo missense variant in FEM1B were identified: NM_015322.5:c.377G>A NP_056137.1:p.(Arg126Gln) (FEM1BR126Q). Affected individuals shared a severe neurodevelopmental disorder with behavioral phenotypes and a variable set of malformations, including brain anomalies, clubfeet, skeletal abnormalities, and facial dysmorphism. Overexpression of the FEM1BR126Q variant but not FEM1B wild-type protein, during mouse brain development, resulted in delayed neuronal migration of the target cells. In addition, the individuals' cells exhibited signs of oxidative stress and induction of type I interferon signaling. CONCLUSION: Overall, our data indicate that p.(Arg126Gln) induces aberrant FEM1B activation, resulting in a gain-of-function mechanism associated with a severe syndromic developmental disorder in humans.

Expanding the genetics and phenotypes of ocular congenital cranial dysinnervation disorders.

PURPOSE: To identify genetic etiologies and genotype/phenotype associations for unsolved ocular congenital cranial dysinnervation disorders (oCCDDs). METHODS: We coupled phenotyping with exome or genome sequencing of 467 probands (550 affected and 1108 total individuals) with genetically unsolved oCCDDs, integrating analyses of pedigrees, human and animal model phenotypes, and de novo variants to identify rare candidate single nucleotide variants, insertion/deletions, and structural variants disrupting protein-coding regions. Prioritized variants were classified for pathogenicity and evaluated for genotype/phenotype correlations. RESULTS: Analyses elucidated phenotypic subgroups, identified pathogenic/likely pathogenic variant(s) in 43/467 probands (9.2%), and prioritized variants of uncertain significance in 70/467 additional probands (15.0%). These included known and novel variants in established oCCDD genes, genes associated with syndromes that sometimes include oCCDDs (e.g., MYH10, KIF21B, TGFBR2, TUBB6), genes that fit the syndromic component of the phenotype but had no prior oCCDD association (e.g., CDK13, TGFB2), genes with no reported association with oCCDDs or the syndromic phenotypes (e.g., TUBA4A, KIF5C, CTNNA1, KLB, FGF21), and genes associated with oCCDD phenocopies that had resulted in misdiagnoses. CONCLUSION: This study suggests that unsolved oCCDDs are clinically and genetically heterogeneous disorders often overlapping other Mendelian conditions and nominates many candidates for future replication and functional studies.

Recessive variants in COL25A1 gene as novel cause of arthrogryposis multiplex congenita with ocular congenital cranial dysinnervation disorder.

A proper interaction between muscle-derived collagen XXV and its motor neuron-derived receptors protein tyrosine phosphatases σ and δ (PTP σ/δ) is indispensable for intramuscular motor innervation. Despite this, thus far, pathogenic recessive variants in the COL25A1 gene had only been detected in a few patients with isolated ocular congenital cranial dysinnervation disorders. Here we describe five patients from three unrelated families with recessive missense and splice site COL25A1 variants presenting with a recognizable phenotype characterized by arthrogryposis multiplex congenita with or without an ocular congenital cranial dysinnervation disorder phenotype. The clinical features of the older patients remained stable over time, without central nervous system involvement. This study extends the phenotypic and genotypic spectrum of COL25A1 related conditions, and further adds to our knowledge of the complex process of intramuscular motor innervation. Our observations indicate a role for collagen XXV in regulating the appropriate innervation not only of extraocular muscles, but also of bulbar, axial, and limb muscles in the human.

Decreased ACKR3 (CXCR7) function causes oculomotor synkinesis in mice and humans.

Oculomotor synkinesis is the involuntary movement of the eyes or eyelids with a voluntary attempt at a different movement. The chemokine receptor CXCR4 and its ligand CXCL12 regulate oculomotor nerve development; mice with loss of either molecule have oculomotor synkinesis. In a consanguineous family with congenital ptosis and elevation of the ptotic eyelid with ipsilateral abduction, we identified a co-segregating homozygous missense variant (c.772G>A) in ACKR3, which encodes an atypical chemokine receptor that binds CXCL12 and functions as a scavenger receptor, regulating levels of CXCL12 available for CXCR4 signaling. The mutant protein (p.V258M) is expressed and traffics to the cell surface but has a lower binding affinity for CXCL12. Mice with loss of Ackr3 have variable phenotypes that include misrouting of the oculomotor and abducens nerves. All embryos show oculomotor nerve misrouting, ranging from complete misprojection in the midbrain, to aberrant peripheral branching, to a thin nerve, which aberrantly innervates the lateral rectus (as seen in Duane syndrome). The abducens nerve phenotype ranges from complete absence, to aberrant projections within the orbit, to a normal trajectory. Loss of ACKR3 in the midbrain leads to downregulation of CXCR4 protein, consistent with reports that excess CXCL12 causes ligand-induced degradation of CXCR4. Correspondingly, excess CXCL12 applied to ex vivo oculomotor slices causes axon misrouting, similar to inhibition of CXCR4. Thus, ACKR3, through its regulation of CXCL12 levels, is an important regulator of axon guidance in the oculomotor system; complete loss causes oculomotor synkinesis in mice, while reduced function causes oculomotor synkinesis in humans.

TUBB3 Arg262His causes a recognizable syndrome including CFEOM3, facial palsy, joint contractures, and early-onset peripheral neuropathy.

Microtubules are formed from heterodimers of alpha- and beta-tubulin, each of which has multiple isoforms encoded by separate genes. Pathogenic missense variants in multiple different tubulin isoforms cause brain malformations. Missense mutations in TUBB3, which encodes the neuron-specific beta-tubulin isotype, can cause congenital fibrosis of the extraocular muscles type 3 (CFEOM3) and/or malformations of cortical development, with distinct genotype-phenotype correlations. Here, we report fourteen individuals from thirteen unrelated families, each of whom harbors the identical NM_006086.4 (TUBB3):c.785G>A (p.Arg262His) variant resulting in a phenotype we refer to as the TUBB3 R262H syndrome. The affected individuals present at birth with ptosis, ophthalmoplegia, exotropia, facial weakness, facial dysmorphisms, and, in most cases, distal congenital joint contractures, and subsequently develop intellectual disabilities, gait disorders with proximal joint contractures, Kallmann syndrome (hypogonadotropic hypogonadism and anosmia), and a progressive peripheral neuropathy during the first decade of life. Subsets may also have vocal cord paralysis, auditory dysfunction, cyclic vomiting, and/or tachycardia at rest. All fourteen subjects share a recognizable set of brain malformations, including hypoplasia of the corpus callosum and anterior commissure, basal ganglia malformations, absent olfactory bulbs and sulci, and subtle cerebellar malformations. While similar, individuals with the TUBB3 R262H syndrome can be distinguished from individuals with the TUBB3 E410K syndrome by the presence of congenital and acquired joint contractures, an earlier onset peripheral neuropathy, impaired gait, and basal ganglia malformations.

Recessive MYF5 Mutations Cause External Ophthalmoplegia, Rib, and Vertebral Anomalies.

MYF5 is member of the Myc-like basic helix-loop-helix transcription factor family and, in cooperation with other myogenic regulatory factors MYOD and MYF5, is a key regulator of early stages of myogenesis. Here, we report three consanguineous families with biallelic homozygous loss-of-function mutations in MYF5 who define a clinical disorder characterized by congenital ophthalmoplegia with scoliosis and vertebral and rib anomalies. The clinical phenotype overlaps strikingly with that reported in several Myf5 knockout mouse models. Affected members of two families share a haploidentical region that contains a homozygous 10 bp frameshift mutation in exon 1 of MYF5 (c.23_32delAGTTCTCACC [p.Gln8Leufs∗86]) predicted to undergo nonsense-mediated decay. Affected members of the third family harbor a homozygous missense change in exon 1 of MYF5 (c.283C>T [p.Arg95Cys]). Using in vitro assays, we show that this missense mutation acts as a loss-of-function allele by impairing MYF5 DNA binding and nuclear localization. We performed whole-genome sequencing in one affected individual with the frameshift mutation and did not identify additional rare variants in the haploidentical region that might account for differences in severity among the families. These data support the direct role of MYF5 in rib, spine, and extraocular muscle formation in humans.

Optic Nerve Head and Retinal Abnormalities Associated with Congenital Fibrosis of the Extraocular Muscles.

Congenital fibrosis of the extraocular muscles (CFEOM) is a congenital cranial dysinnervation disorder caused by developmental abnormalities affecting cranial nerves/nuclei innervating the extraocular muscles. Autosomal dominant CFEOM arises from heterozygous missense mutations of KIF21A or TUBB3. Although spatiotemporal expression studies have shown KIF21A and TUBB3 expression in developing retinal ganglion cells, it is unclear whether dysinnervation extends beyond the oculomotor system. We aimed to investigate whether dysinnervation extends to the visual system by performing high-resolution optical coherence tomography (OCT) scans characterizing retinal ganglion cells within the optic nerve head and retina. Sixteen patients with CFEOM were screened for mutations in KIF21A, TUBB3, and TUBB2B. Six patients had apparent optic nerve hypoplasia. OCT showed neuro-retinal rim loss. Disc diameter, rim width, rim area, and peripapillary nerve fiber layer thickness were significantly reduced in CFEOM patients compared to controls (p < 0.005). Situs inversus of retinal vessels was seen in five patients. Our study provides evidence of structural optic nerve and retinal changes in CFEOM. We show for the first time that there are widespread retinal changes beyond the retinal ganglion cells in patients with CFEOM. This study shows that the phenotype in CFEOM extends beyond the motor nerves.

Altered White Matter Organization in the TUBB3 E410K Syndrome.

Seven unrelated individuals (four pediatric, three adults) with the TUBB3 E410K syndrome, harboring identical de novo heterozygous TUBB3 c.1228 G>A mutations, underwent neuropsychological testing and neuroimaging. Despite the absence of cortical malformations, they have intellectual and social disabilities. To search for potential etiologies for these deficits, we compared their brain's structural and white matter organization to 22 controls using structural and diffusion magnetic resonance imaging. Diffusion images were processed to calculate fractional anisotropy (FA) and perform tract reconstructions. Cortical parcellation-based network analysis and gyral topology-based FA analyses were performed. Major interhemispheric, projection and intrahemispheric tracts were manually segmented. Subjects had decreased corpus callosum volume and decreased network efficiency. While only pediatric subjects had diffuse decreases in FA predominantly affecting mid- and long-range tracts, only adult subjects had white matter volume loss associated with decreased cortical surface area. All subjects showed aberrant corticospinal tract trajectory and bilateral absence of the dorsal language network long segment. Furthermore, pediatric subjects had more tracts with decreased FA compared with controls than did adult subjects. These findings define a TUBB3 E410K neuroimaging endophenotype and lead to the hypothesis that the age-related changes are due to microscopic intrahemispheric misguided axons that are pruned during maturation.

Loss of MAFB Function in Humans and Mice Causes Duane Syndrome, Aberrant Extraocular Muscle Innervation, and Inner-Ear Defects.

Duane retraction syndrome (DRS) is a congenital eye-movement disorder defined by limited outward gaze and retraction of the eye on attempted inward gaze. Here, we report on three heterozygous loss-of-function MAFB mutations causing DRS and a dominant-negative MAFB mutation causing DRS and deafness. Using genotype-phenotype correlations in humans and Mafb-knockout mice, we propose a threshold model for variable loss of MAFB function. Postmortem studies of DRS have reported abducens nerve hypoplasia and aberrant innervation of the lateral rectus muscle by the oculomotor nerve. Our studies in mice now confirm this human DRS pathology. Moreover, we demonstrate that selectively disrupting abducens nerve development is sufficient to cause secondary innervation of the lateral rectus muscle by aberrant oculomotor nerve branches, which form at developmental decision regions close to target extraocular muscles. Thus, we present evidence that the primary cause of DRS is failure of the abducens nerve to fully innervate the lateral rectus muscle in early development.

Human Schwann cells exhibit long-term cell survival, are not tumorigenic and promote repair when transplanted into the contused spinal cord.

The transplantation of rodent Schwann cells (SCs) provides anatomical and functional restitution in a variety of spinal cord injury (SCI) models, supporting the recent translation of SCs to phase 1 clinical trials for human SCI. Whereas human (Hu)SCs have been examined experimentally in a complete SCI transection paradigm, to date the reported behavior of SCs when transplanted after a clinically relevant contusive SCI has been restricted to the use of rodent SCs. Here, in a xenotransplant, contusive SCI paradigm, the survival, biodistribution, proliferation and tumorgenicity as well as host responses to HuSCs, cultured according to a protocol analogous to that developed for clinical application, were investigated. HuSCs persisted within the contused nude rat spinal cord through 6 months after transplantation (longest time examined), exhibited low cell proliferation, displayed no evidence of tumorigenicity and showed a restricted biodistribution to the lesion. Neuropathological examination of the CNS revealed no adverse effects of HuSCs. Animals exhibiting higher numbers of surviving HuSCs within the lesion showed greater volumes of preserved white matter and host rat SC and astrocyte ingress as well as axon ingrowth and myelination. These results demonstrate the safety of HuSCs when employed in a clinically relevant experimental SCI paradigm. Further, signs of a potentially positive influence of HuSC transplants on host tissue pathology were observed. These findings show that HuSCs exhibit a favorable toxicity profile for up to 6 months after transplantation into the contused rat spinal cord, an important outcome for FDA consideration of their use in human clinical trials.

Two unique TUBB3 mutations cause both CFEOM3 and malformations of cortical development.

One set of missense mutations in the neuron specific beta tubulin isotype 3 (TUBB3) has been reported to cause malformations of cortical development (MCD), while a second set has been reported to cause isolated or syndromic Congenital Fibrosis of the Extraocular Muscles type 3 (CFEOM3). Because TUBB3 mutations reported to cause CFEOM had not been associated with cortical malformations, while mutations reported to cause MCD had not been associated with CFEOM or other forms of paralytic strabismus, it was hypothesized that each set of mutations might alter microtubule function differently. Here, however, we report two novel de novo heterozygous TUBB3 amino acid substitutions, G71R and G98S, in four patients with both MCD and syndromic CFEOM3. These patients present with moderately severe CFEOM3, nystagmus, torticollis, and developmental delay, and have intellectual and social disabilities. Neuroimaging reveals defective cortical gyration, as well as hypoplasia or agenesis of the corpus callosum and anterior commissure, malformations of hippocampi, thalami, basal ganglia and cerebella, and brainstem and cranial nerve hypoplasia. These new TUBB3 substitutions meld the two previously distinct TUBB3-associated phenotypes, and implicate similar microtubule dysfunction underlying both.

Dietary counselling has no effect on cardiovascular risk factors among Chinese Grade 1 hypertensive patients: a randomized controlled trial.

AIMS: To evaluate the effectiveness of Dietary Approaches to Stop Hypertension (DASH) by one-off dietary counselling on reducing cardiovascular risk factors among Chinese Grade 1 hypertensive patients in primary care. METHODS AND RESULTS: A parallel-group, randomized controlled trial (ChiCTR-TRC-13003014) was conducted among patients (40-70 years old) newly diagnosed with Grade 1 hypertension in primary care settings in Hong Kong. Subjects were randomized to usual care (standard education, control) (n = 275), or usual care plus DASH-based dietary counselling (intervention) (n = 281). The study endpoints included blood pressure (BP), lipid profile, and body mass index (BMI) at 6- and 12-months. Outcome data were available for 504 (90.6%) and 485 (87.2%) patients at 6 and 12 months, respectively. Blood pressure levels reduced in both groups at follow-ups. However, the intervention group did not show a significantly greater reduction in either systolic BP (-0.7 mmHg, 95%CI -3.0-1.5 at 6-month; -0.1 mmHg, 95%CI -2.4-2.2 at 12-month) or diastolic BP (-1.0 mmHg, 95%CI -2.7-0.7 at 6-month; -1.1 mmHg, 95%CI -2.9-0.6 at 12-month), when compared with the control group. The improvements in lipid profile and BMI were observed among all subjects, yet no significant differences were detected between intervention and control groups. CONCLUSION: The DASH diet by one-off dietitian counselling which resembled the common primary care practice might confer no added long-term benefits on top of physician's usual care in optimizing cardiovascular risk factors. Physicians may still practice standard usual care, yet further explorations on different DASH delivery models are warranted to inform best clinical practice.

Adiposity and influenza-associated respiratory mortality: a cohort study.

BACKGROUND: Obesity was first noted as a risk factor for severe illness associated with pandemic H1N1 infection in 2009, but the relationship between obesity and seasonal influenza remains unclear. METHODS: We used data from a population-based cohort comprising 66 820 older (≥65 years) participants with a follow-up period from 1998 to 2012. The impact of influenza activity on respiratory mortality rates was estimated using a Cox proportional hazards model adjusted for comorbidities, meteorological factors, and other co-circulating respiratory viruses. We also tested whether the association of influenza with respiratory mortality varied with obesity and/or health status. As a control outcome, we similarly assessed the association of influenza with deaths from external causes, because these deaths should be unrelated to influenza. RESULTS: Seasonal influenza activity was associated with higher respiratory mortality (hazard ratio [HR], 1.13 for influenza activity in the influenza season vs noninfluenza season; 95% confidence interval [CI], 1.05-1.22). The effect of seasonal influenza was 19% greater in obese individuals than normal-weight individuals (HR, 1.19; 95% CI, 1.01-1.42). The marginally significant and greater effect modification of obesity status on the association between seasonal influenza and respiratory mortality was also observed among older people in good health (HR, 1.35; 95% CI, .97-1.87). No such relations were observed for death from external causes. CONCLUSIONS: Obesity aggravates the effect of seasonal influenza on respiratory mortality. Priority for influenza vaccine should be considered for obese older people to decrease the burden of influenza.

HOXB1 founder mutation in humans recapitulates the phenotype of Hoxb1-/- mice.

Members of the highly conserved homeobox (HOX) gene family encode transcription factors that confer cellular and tissue identities along the antero-posterior axis of mice and humans. We have identified a founder homozygous missense mutation in HOXB1 in two families from a conservative German American population. The resulting phenotype includes bilateral facial palsy, hearing loss, and strabismus and correlates extensively with the previously reported Hoxb1(-/-) mouse phenotype. The missense variant is predicted to result in the substitution of a cysteine for an arginine at amino acid residue 207 (Arg207Cys), which corresponds to the highly conserved Arg5 of the homeodomain. Arg5 interacts with thymine in the minor groove of DNA through hydrogen bonding and electrostatic attraction. Molecular modeling and an in vitro DNA-protein binding assay predict that the mutation would disrupt these interactions, destabilize the HOXB1:PBX1:DNA complex, and alter HOXB1 transcriptional activity.

Factors associated with grade 1 hypertension: implications for hypertension care based on the Dietary Approaches to Stop Hypertension (DASH) in primary care settings.

BACKGROUND: A Reference Framework for Hypertension Care was recently developed by Hong Kong government to emphasise the importance of primary care for subjects with high blood pressure (BP). The Dietary Approaches to Stop Hypertension (DASH) interventional regime was recommended for patients aged 40-70 years with grade 1 hypertension (having systolic BP of 140-159 mmHg and/or diastolic BP of 90-99 mmHg). This study explored factors associated with grade 1 hypertension among subjects screened in primary care settings. METHODS: The study sample consisted of community dwellers (N = 10,693) enrolled in a primary care programme in which participants overall had similar characteristics when compared to the Hong Kong population census. Invitation phone calls were given by trained researchers to a randomly selected subjects (N = 2,673, [50% of total subjects aged 40-70 years]) between January and June 2013. BP and body mass index (BMI) were measured by trained clinical professionals according to a standard protocol. Interviewer-administered survey questionnaires were used to collect self-report information on socio-demographics, family history, and lifestyle characteristics. Multiple logistic regression analysis was performed to explore factors associated with grade 1 hypertension. Adjusted odds ratios (aORs) were estimated with 95% confidence intervals (CI). RESULTS: A total of 679 out of 2,673 subjects agreed to participate in the screening and completed the baseline assessment (100% completion rate), among which, 320 subjects (47.1%, [320/679]) were grade 1 hypertensive. Unhealthy diet (aOR = 2.19, 95%CI 1.04-4.62), irregular meals (aOR = 1.47, 95%CI 1.11-1.95), BMI >27.5 kg/m(2) (aOR = 1.87, 95%CI 1.53-2.27), duration of cigarette smoking (aOR = 1.83 per year), increased daily cigarette consumption (aOR =1.59 per pack [20 cigarettes per pack]), duration of alcohol drinking (aOR = 1.65 per year), and higher frequency of weekly binge drinking (aOR = 1.87 per occasion) were independently associated with grade 1 hypertension. The increase in the number of risk factors combined significantly correlated with higher predicted probability of grade 1 hypertension. CONCLUSIONS: Dietary-intake factors were significantly associated with grade 1 hypertension, echoing the recommendation in the Reference Framework on incorporating dietary-related intervention based on the DASH approach for hypertension care in primary care settings. The association between aggregate risk factors and grade 1 hypertension should also be taken into consideration in long-term preventive strategy.

An in-depth pilot study on patterns, destinations, and purposes of walking in Hong Kong older adults.

Walking is a suitable activity for older adults and has physical and mental health benefits. To devise interventions that impact levels of walking it is necessary to first understand the purposes for which people walk and the destinations to which they walk. Using a 7-day diary and accelerometry, this study investigated destinations and purposes of walking in older adult residents of an ultra-dense Asian city. Participants reported an average of 17.1 walking trips per week and total weekly accelerometer/diary determined trip walking time averaged 735 min per week; much higher than reported for older adults in non-Asian settings. The most common destinations were within the neighborhood: parks and streets for recreation walking and shops and eating places for transport-related walking. Errands and eating were the most common purposes for transportation trips. The study results can help inform urban design to encourage walking.

An inherited TUBB2B mutation alters a kinesin-binding site and causes polymicrogyria, CFEOM and axon dysinnervation.

Microtubules are essential components of axon guidance machinery. Among ß-tubulin mutations, only those in TUBB3 have been shown to cause primary errors in axon guidance. All identified mutations in TUBB2B result in polymicrogyria, but it remains unclear whether TUBB2B mutations can cause axon dysinnervation as a primary phenotype. We have identified a novel inherited heterozygous missense mutation in TUBB2B that results in an E421K amino acid substitution in a family who segregates congenital fibrosis of the extraocular muscles (CFEOM) with polymicrogyria. Diffusion tensor imaging of brains of affected family members reveals aberrations in the trajectories of commissural projection neurons, implying a paucity of homotopic connections. These observations led us to ask whether axon dysinnervation is a primary phenotype, and why the E421K, but not other, TUBB2B substitutions cause CFEOM. Expression of exogenous Tubb2b-E421K in developing callosal projection neurons is sufficient to perturb homotopic connectivity, without affecting neuronal production or migration. Using in vitro biochemical assays and yeast genetics, we find that TUBB2B-E421K αß-heterodimers are incorporated into the microtubule network where they alter microtubule dynamics and can reduce kinesin localization. These data provide evidence that TUBB2B mutations can cause primary axon dysinnervation. Interestingly, by incorporating into microtubules and altering their dynamic properties, the E421K substitution behaves differently than previously identified TUBB2B substitutions, providing mechanistic insight into the divergence between resulting phenotypes. Together with previous studies, these findings highlight that ß-tubulin isotypes function in both conserved and divergent ways to support proper human nervous system development.

Diagnostic distinctions and genetic analysis of patients diagnosed with moebius syndrome.

OBJECTIVE: To improve diagnostic assessment in Moebius syndrome by (1) creating more selective diagnostic subgroups and (2) conducting genetic evaluation in a large patient cohort. DESIGN: Prospective, observational study. PARTICIPANTS: Attendees of 3 consecutive Moebius syndrome conferences held in the United States, with a prior diagnosis of Moebius syndrome, were invited to participate. METHODS: Participants underwent standardized ophthalmologic examination for Moebius syndrome minimum diagnostic criteria (MDC) (congenital, nonprogressive facial palsy, and abduction deficit) and genetic testing for HOXA1, HOXB1, and TUBB3 mutations. MAIN OUTCOME MEASURES: The number of patients meeting MDC and the number of patients with confirmed genetic mutation. RESULTS: A total of 112 participants from 107 families enrolled. Nineteen percent of participants (21/112) did not meet accepted MDC for Moebius syndrome because they had abduction deficits without facial palsy or facial palsy with full ocular motility. All 5 families with 2 affected individuals had at least 1 family member in this category, including 2 siblings with comitant strabismus who harbored a HOXB1 mutation. Four unrelated participants, also not meeting MDC, had large-angle exotropia, vertical gaze deficiency, and ptosis consistent with congenital fibrosis of the extraocular muscles type 3 (CFEOM3); 1 patient harbored a novel TUBB3 mutation, and 3 patients harbored previously reported de novo TUBB3 mutations. Three percent of participants (3/112) met MDC but also had restricted vertical gaze. The remaining 88 participants (79%) met MDC and had full vertical gaze. This group had relatively homogeneous findings, and none had a family history of Moebius syndrome. Two previously undescribed phenomena were observed in this category: (1) volitional Bell's phenomenon and (2) intorsion with fixation. CONCLUSIONS: Although the genetic contributors to classic Moebius syndrome remain elusive, accuracy in clinical evaluation will properly subdivide patients to facilitate genetic testing as new candidate genes are identified. Failure to test ocular motility may lead to misdiagnosis of Moebius syndrome, especially in patients who have facial palsy with full ductions. Patients with exotropia, vertical gaze limitation, and ptosis do not have classic Moebius syndrome and may have TUBB3 mutations associated with CFEOM3. To optimize genetic analysis, we propose adding "full vertical motility" to the MDC for Moebius syndrome.

Self-reported diabetes and mortality in a prospective Chinese elderly cohort study in Hong Kong.

OBJECTIVE: In Western countries, diabetes mellitus is positively associated with death from all- and specific-causes including cancer, cardiovascular and respiratory diseases. In a Chinese setting with a different disease pattern: high diabetes rates in a relatively non-obese population with low ischemic heart disease (IHD) rates where diabetes is positively associated with IHD, we examined the association of self-reported diabetes with death among older people. METHODS: Multivariable Cox regression analysis was used in a population-based prospective cohort of 66,820 Chinese (65+ years) enrolled from July 1998 to December 2001 at Elderly Health Centers of the Hong Kong Government Department of Health, followed until May 31, 2012. RESULTS: During 10.9 years of follow-up, 19,845 deaths occurred. Self-reported diabetes was associated with death from all-causes (hazard ratio (HR)=1.56, 95% confidence interval (CI) 1.51, 1.62), cardiovascular disease (HR=1.84, 95% CI 1.72, 1.96), cancer (HR=1.11, 95% CI 1.03 to 1.20), liver cancer (HR=1.38, 95% CI 1.13 to 1.69) and stomach cancer (HR=1.38, 95% CI 1.03 to 1.85), adjusted for age, sex, socio-economic position, alcohol use, smoking, exercise and body mass index. CONCLUSION: Such a pattern of associations suggests that further investigation into the drivers of diabetes is required in this and similar populations.