Cerebral folate deficiency: a treatable cause of late deterioration in epilepsy with developmental delay.

A 25-year-old woman with childhood-onset refractory epilepsy and developmental delay experienced a gradually progressive marked deterioration in mobility and seizure control, with language regression. Investigation identified a homozygous deletion within the contactin-associated protein-like 2 gene (CNTNAP2), underlying her early presentation, but also cerebral folate deficiency that most likely contributed to her later deterioration. Following antiseizure medication adjustment and treatment with folinic acid, she stabilised with improved seizure control and limited improvement in language and motor function; she has remained neurologically stable for more than a decade. That the previously observed neurological decline was halted by folinic acid replacement supports this being due to cerebral folate deficiency. Metabolic conditions are less well recognised in adults and can be under-diagnosed. They are potentially treatable and should be considered even in the presence of another cause, particularly when the presentation is not fully compatible.

Heterozygous KIDINS220/ARMS nonsense variants cause spastic paraplegia, intellectual disability, nystagmus, and obesity.

We identified de novo nonsense variants in KIDINS220/ARMS in three unrelated patients with spastic paraplegia, intellectual disability, nystagmus, and obesity (SINO). KIDINS220 is an essential scaffold protein coordinating neurotrophin signal pathways in neurites and is spatially and temporally regulated in the brain. Molecular analysis of patients' variants confirmed expression and translation of truncated transcripts similar to recently characterized alternative terminal exon splice isoforms of KIDINS220 KIDINS220 undergoes extensive alternative splicing in specific neuronal populations and developmental time points, reflecting its complex role in neuronal maturation. In mice and humans, KIDINS220 is alternative spliced in the middle region as well as in the last exon. These full-length and KIDINS220 splice variants occur at precise moments in cortical, hippocampal, and motor neuron development, with splice variants similar to the variants seen in our patients and lacking the last exon of KIDINS220 occurring in adult rather than in embryonic brain. We conducted tissue-specific expression studies in zebrafish that resulted in spasms, confirming a functional link with disruption of the KIDINS220 levels in developing neurites. This work reveals a crucial physiological role of KIDINS220 in development and provides insight into how perturbation of the complex interplay of KIDINS220 isoforms and their relative expression can affect neuron control and human metabolism. Altogether, we here show that de novo protein-truncating KIDINS220 variants cause a new syndrome, SINO. This is the first report of KIDINS220 variants causing a human disease.

Brown-Vialetto-Van Laere syndrome, a ponto-bulbar palsy with deafness, is caused by mutations in c20orf54.

Brown-Vialetto-Van Laere syndrome is a rare neurological disorder with a variable age at onset and clinical course. The key features are progressive ponto-bulbar palsy and bilateral sensorineural deafness. A complex neurological phenotype with a mixed picture of upper and lower motor neuron involvement reminiscent of amyotrophic lateral sclerosis evolves with disease progression. We identified a candidate gene, C20orf54, by studying a consanguineous family with multiple affected individuals and subsequently demonstrated that mutations in this gene were the cause of disease in other, unrelated families.

Genetics of gynaecological disorders.

From genomic imbalances associated with developmental abnormalities of the female genital tract to the molecular mechanisms underpinning endometriosis and uterine leiomyomatosis, new technologies have allowed the exploration of the genetic contribution and mapping the molecular pathways underpinning common and rare gynaecological conditions. While some of these conditions have historically been considered sporadic, recent research has demonstrated their potentially heritable nature linked to single genes or copy number variants. The phenotypic variability including non-penetrance indicates their multifactorial, complex aetiology encompassing genetic, epigenetic and environmental influences. Although genetic tests are not routinely conducted in gynaecological practice, there is an increasing body of evidence suggesting that, in appropriate cases, molecular investigations such as array CGH analysis may be an important part of the diagnostic algorithm. The subtlety of clinical features, especially in the context of syndromic diagnoses, requires the practitioner to become familiar with those conditions and the approach to diagnostic investigations. This chapter combines the recent research output related to gynaecological disorders with a clinical genetics approach aiming to highlight the multisystem character of some of these conditions, their implications for management, reproductive risks and options, and the importance of genetic counselling.

Oculoauriculovertebral spectrum phenotype caused by an unbalanced t(5;8)(p15.31;p23.1) rearrangement.

We present two siblings with oculoauriculovertebral spectrum phenotype (Goldenhar syndrome) and an unbalanced translocation t(5;8)(p15.31;p23.1) resulting in monosomy for the region 5p15.31 to 5pter and trisomy for 8p23.2 to 8pter region. The father was a carrier of the balanced rearrangement 46,XY,t(5;8)(p15.31;8p23.1). To our knowledge this is the first report of Goldenhar phenotype in association with an unbalanced (5p;8p) translocation.

Structural pituitary abnormalities associated with CHARGE syndrome.

INTRODUCTION: CHARGE syndrome is a multisystem disorder that, in addition to Kallmann syndrome/isolated hypogonadotrophic hypogonadism, has been associated with anterior pituitary hypoplasia (APH). However, structural abnormalities such as an ectopic posterior pituitary (EPP) have not yet been described in such patients. OBJECTIVE: The aims of the study were: 1) to describe the association between CHARGE syndrome and a structurally abnormal pituitary gland; and 2) to investigate whether CHD7 variants, which are identified in 65% of CHARGE patients, are common in septo-optic dysplasia /hypopituitarism. METHODS: We describe 2 patients with features of CHARGE and EPP. CHD7 was sequenced in these and other patients with septo-optic dysplasia/hypopituitarism. RESULTS: EPP, APH, and GH, TSH, and probable LH/FSH deficiency were present in 1 patient, and EPP and APH with GH, TSH, LH/FSH, and ACTH deficiency were present in another patient, both of whom had features of CHARGE syndrome. Both had variations in CHD7 that were novel and undetected in control cohorts or in the international database of CHARGE patients, but were also present in their unaffected mothers. No CHD7 variants were detected in the patients with septo-optic dysplasia/hypopituitarism without additional CHARGE features. CONCLUSION: We report a novel association between CHARGE syndrome and structural abnormalities of the pituitary gland in 2 patients with variations in CHD7 that are of unknown significance. However, CHD7 mutations are an uncommon cause of septo-optic dysplasia or hypopituitarism. Our data suggest the need for evaluation of pituitary function/anatomy in patients with CHARGE syndrome.

Clinical and neuropathological features of X-linked spinal muscular atrophy (SMAX2) associated with a novel mutation in the UBA1 gene.

Infantile-onset X-linked spinal muscular atrophy (SMAX2) is a rare lethal disorder linked to mutations in the UBA1 (previously UBE1) gene, encoding ubiquitin-activating enzyme 1 that has an important role in the ubiquitin-proteasome pathway. Published pathological reports are scarce. Here we report a male infant who presented from birth with predominantly truncal hypotonia following an antenatal history of reduced fetal movements. He had a myopathic face, profound weakness, multiple contractures and areflexia. Creatine kinase was moderately raised. Brain MRI showed non-specific symmetrical periventricular white matter changes. Neurophysiology revealed evidence of motor and sensory involvement and muscle biopsy showed marked inflammatory changes with subtle features suggestive of acute denervation. UBA1 sequencing revealed a novel hemizygous missense mutation (c.1670A>T; p.Glu557Val). He died from progressive respiratory failure at 4 months. On post mortem assessment, in addition to severe ventral motor neuron pathology, there was widespread involvement of the sensory system, as well as developmental and degenerative cerebellar abnormalities. In contrast to typical SMN1-associated SMA, the thalamus was unaffected. These findings indicate that SMAX2 is more accurately classified as a motor sensory neuronopathy rather than a pure anterior horn cell disorder. Ubiquitin-proteasome pathway defects may not only cause neurodegeneration but also affect normal neuronal development.

A transition zone complex regulates mammalian ciliogenesis and ciliary membrane composition.

Mutations affecting ciliary components cause ciliopathies. As described here, we investigated Tectonic1 (Tctn1), a regulator of mouse Hedgehog signaling, and found that it is essential for ciliogenesis in some, but not all, tissues. Cell types that do not require Tctn1 for ciliogenesis require it to localize select membrane-associated proteins to the cilium, including Arl13b, AC3, Smoothened and Pkd2. Tctn1 forms a complex with multiple ciliopathy proteins associated with Meckel and Joubert syndromes, including Mks1, Tmem216, Tmem67, Cep290, B9d1, Tctn2 and Cc2d2a. Components of this complex co-localize at the transition zone, a region between the basal body and ciliary axoneme. Like Tctn1, loss of Tctn2, Tmem67 or Cc2d2a causes tissue-specific defects in ciliogenesis and ciliary membrane composition. Consistent with a shared function for complex components, we identified a mutation in TCTN1 that causes Joubert syndrome. Thus, a transition zone complex of Meckel and Joubert syndrome proteins regulates ciliary assembly and trafficking, suggesting that transition zone dysfunction is the cause of these ciliopathies.