Treatable inborn errors of metabolism presenting as cerebral palsy mimics: systematic literature review

Clinical Characteristics Suggestive of a Genetic Cause in Cerebral Palsy: A Systematic Review

BACKGROUND

Cerebral palsy (CP) is a clinical diagnosis and was long categorized as an acquired disorder, but more and more genetic etiologies are being identified. This review aims to identify the clinical characteristics that are associated with genetic CP to aid clinicians in selecting candidates for genetic testing.

METHODS

The PubMed database was systematically searched to identify genes associated with CP. The clinical characteristics accompanying these genetic forms of CP were compared with published data of large CP populations resulting in the identification of potential indicators of genetic CP.

RESULLTS

Of 1930 articles retrieved, 134 were included. In these, 55 CP genes (described in two or more cases, n = 272) and 79 candidate genes (described in only one case) were reported. The most frequently CP-associated genes were PLP1 (21 cases), ARG1 (17 cases), and CTNNB1 (13 cases). Dyskinesia and the absence of spasticity were identified as strong potential indicators of genetic CP. Presence of intellectual disability, no preterm birth, and no unilateral distribution of symptoms were classified as moderate genetic indicators.

CONCLUSIONS

Genetic causes of CP are increasingly identified. The clinical characteristics associated with genetic CP can aid clinicians regarding to which individual with CP to offer genetic testing. The identified potential genetic indicators need to be validated in large CP cohorts but can provide the first step toward a diagnostic algorithm for genetic CP.

Pediatric Rehabilitation for Walking Difficulty and Calf Muscle Pain in a 13-Year-Old Male With Spastic Diplegic Cerebral Palsy and Clubfoot Deformity: A Case Report

Cerebral palsy (CP) manifests as atypical muscle tone, posture, and movement, and is classified into four main types: extrapyramidal (dyskinetic), spastic quadriplegia, spastic hemiplegia, and spastic diplegia. Patients with CP might move awkwardly because of this since it indicates that their muscles are tense. We report the case of a 13-year-old child who complained of soreness in his right calf muscle and trouble walking over the previous two years. His condition is recognized as spastic diplegic CP. This report aims to understand the impact of neurophysiotherapy procedures in the context of CP. Physical therapy employs various therapeutic techniques to help patients become more independent in carrying out their everyday tasks and enhance their quality of life, including stretching, proprioceptive neuromuscular facilitation, limb strengthening exercises, and gait training. Early rehabilitation aids in treating various motor functions, such as balance, posture, oral motor functioning, fine motor skills, gross motor skills, muscle control, muscle tone, reflexes, and body movement. It also helps children with CP reach their full potential for physical independence and fitness and enhances the quality of life for both the child and the family. Pediatric rehabilitation yields significant benefits in alleviating walking difficulty and calf muscle pain in individuals with spastic diplegic CP and clubfoot deformity.

Mimickers of hypoxic-ischaemic brain injury in term neonates: What the radiologist should know

Patterns of neonatal hypoxic-ischaemic brain injury (HIBI) are fairly well known. There are, however, other diagnoses with imaging patterns that may mimic HIBI. A review of MRI studies was conducted for children with suspected cerebral palsy, correlated with prior imaging, clinical details and laboratory tests where available. In the 63 identified cases, imaging features were, in many cases, very similar to the known patterns of HIBI. The alternative diagnoses can be classified as developmental, vascular, chromosomal, infections, metabolic disorders, and congenital syndromes. These findings are described in this pictorial essay. The potential mimickers of HIBI described in this essay can demonstrate similar imaging appearances to HIBI.

Contribution

There are multiple possible causes of neonatal encephalopathy other than hypoxic-ischaemic encephalopathy. Many conditions may mimic HIBI, each of which can be associated with significant morbidity. It is prudent for the reporting radiologist to be aware of these alternate clinico-radiological diagnoses.

Redefining cerebral palsies as a diverse group of neurodevelopmental disorders with genetic aetiology

Cerebral palsy is a clinical descriptor covering a diverse group of permanent, non-degenerative disorders of motor function. Around one-third of cases have now been shown to have an underlying genetic aetiology, with the genetic landscape overlapping with those of neurodevelopmental disorders including intellectual disability, epilepsy, speech and language disorders and autism. Here we review the current state of genomic testing in cerebral palsy, highlighting the benefits for personalized medicine and the imperative to consider aetiology during clinical diagnosis. With earlier clinical diagnosis now possible, we emphasize the opportunity for comprehensive and early genomic testing as a crucial component of the routine diagnostic work-up in people with cerebral palsy.

CTNNB1-related neurodevelopmental disorder mimics cerebral palsy: case report

While somatic gain-of-function mutations in the CTNNB1 gene cause diverse malignancies, germline loss-of-function mutations cause neurodevelopmental disorders or familial exudative vitreoretinopathy. In particular, CTNNB1-related neurodevelopmental disorders have various phenotypes, and a genotype-phenotype relationship has not been established. We report two patients with CTNNB1-related neurodevelopmental disorder whose clinical features were similar to those of cerebral palsy, hindering diagnosis.

Predictors of whole exome sequencing in dystonic cerebral palsy and cerebral palsy-like disorders

INTRODUCTION

Cerebral palsy (CP) is a group of permanent disorders attributed to non-progressive disturbances that occurred in the developing fetal or infant brain. Cerebral palsy-like (CP-like) disorders may clinically resemble CP but do not fulfill CP criteria and have often a progressive course and/or neurodevelopmental regression. To assess which patients with dystonic CP and dystonic CP-like disorder should undergo Whole Exome Sequencing (WES), we compared the rate of likely causative variants in individuals regarding their clinical picture, co-morbidities, and environmental risk factors.

METHOD

Individuals with early onset neurodevelopmental disorder (ND) manifesting with dystonia as a core feature were divided into CP or CP-like cohorts based on their clinical picture and disease course. Detailed clinical picture, co-morbidities, and environmental risk factors including prematurity, asphyxia, SIRS, IRDS, and cerebral bleeding were evaluated.

RESULTS

A total of 122 patients were included and divided into the CP group with 70 subjects (30 males; mean age 18y5m±16y6m, mean GMFCS score 3.3 ± 1.4), and the CP-like group with 52 subjects (29 males; mean age 17y7m±1y,6 m, mean GMFCS score 2,6 ± 1,5). The WES-based diagnosis was present in 19 (27.1%) CP patients and 30 CP-like patients (57.7%) with genetic conditions overlap in both groups. We found significant differences in diagnostic rate in CP individuals with vs. without risk factors (13.9% vs. 43.3%); Fisher's exact p = 0.0065. We did not observe the same tendency in CP-like (45.5% vs 58.5%); Fisher's exact p = 0.5.

CONCLUSION

WES is a useful diagnostic method for patients with dystonic ND, regardless of their presentation as a CP or CP-like phenotype.

Genomics in Cerebral Palsy phenotype across the lifespan: Comparison of diagnostic yield between children and adult population

PURPOSE

The presentation and underlying etiology of Cerebral Palsy (CP) in general are heterogenous. Clinical features present differently in pediatric versus adult patient populations. Many metabolic and genetic conditions present with clinical symptoms suggestive of CP. Precision medicine practices are currently a standard of care, and Next-Generation-Sequencing (NGS) tools are used for the purpose of diagnosis and management. We describe the diagnostic yield and impact on management of NGS comparing a cohort of 102 children and 37 adults with CP, referred to two tertiary care centres between 2015 and 2020 (adult cohort) and 2017-2020 (pediatric cohort) respectively.

PRINCIPAL RESULTS

In the adult cohort, 28 patients had a positive genetic diagnosis, giving a yield of 75.6%. Their age varied between 18 and 59 years, with a median of 28 years. Out of the positive diagnoses, 12 were consistent with an inborn error of metabolism and in 9 patients (32.1%) some form of treatment or management guideline was recommended. In the pediatric cohort 21 patients had a positive genetic diagnosis and 22 results are still pending, giving a yield of 32.8%. Age at diagnosis ranged between 18 months and 12 years. In 15 patients (71.4%) there was some form of management recommendation. All families benefited from genetic counseling.

MAJOR CONCLUSIONS

Given the combined high yield of positive genetic diagnosis in pediatric and adult cases presenting with symptoms of Cerebral Palsy, and the more readily available Next Generation Sequencing testing in major academic centres, we recommend that either a referral to a pediatric or adult neurometabolic centre to be made, or genetic testing to be initiated where this is available.

Molecular Diagnostic Yield of Exome Sequencing and Chromosomal Microarray in Cerebral Palsy: A Systematic Review and Meta-analysis

Importance

There are many known acquired risk factors for cerebral palsy (CP), but in some cases, CP is evident without risk factors (cryptogenic CP). Early CP cohort studies report a wide range of diagnostic yields for sequence variants assessed by exome sequencing (ES) and copy number variants (CNVs) assessed by chromosomal microarray (CMA).

Objective

To synthesize the emerging CP genetics literature and address the question of what percentage of individuals with CP have a genetic disorder via ES and CMA.

Data Sources

Searched articles were indexed by PubMed with relevant queries pertaining to CP and ES/CMA (query date, March 15, 2022).

Study Selection

Inclusion criteria were as follows: primary research study, case series with 10 or more nonrelated individuals, CP diagnosis, and ES and/or CMA data used for genetic evaluation. Nonblinded review was performed.

Data Extraction and Synthesis

Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines were used for assessing data quality and validity. Data were extracted by a single observer.

Main Outcomes and Measures

A separate meta-analysis was performed for each modality (ES, CMA). The primary outcome was proportion/molecular diagnostic yield (number of patients with a discovered genetic disorder divided by the total number of patients in the cohort), evaluated via meta-analysis of single proportions using random-effects logistic regression. A subgroup meta-analysis was conducted, using risk factor classification as a subgroup. A forest plot was used to display diagnostic yields of individual studies.

Results

In the meta-analysis of ES yield in CP, the overall diagnostic yield of ES among the cohorts (15 study cohorts comprising 2419 individuals from 11 articles) was 23% (95% CI, 15%-34%). The diagnostic yield across cryptogenic CP cohorts was 35% (95% CI, 27%-45%), compared with 7% (95% CI, 4%-12%) across cohorts with known risk factors (noncryptogenic CP). In the meta-analysis of CMA yield in CP, the diagnostic yield of CMA among the cohorts (5 study cohorts comprising 294 individuals from 5 articles) was 5% (95% CI, 2%-12%).

Conclusions and Relevance

Results of this systematic review and meta-analysis suggest that for individuals with cryptogenic CP, ES followed by CMA to identify molecular disorders may be warranted.

Cerebral palsy and related neuromotor disorders: Overview of genetic and genomic studies

Cerebral palsy (CP) is a debilitating condition characterized by abnormal movement or posture, beginning early in development. Early family and twin studies and more recent genomic investigations clearly demonstrate that genetic factors of major effect contribute to the etiology of CP. Most copy number variants and small alterations of nucleotide sequence that cause CP arise as a result of de novo mutations, so studies that estimate heritability on basis of recurrence frequency within families substantially underestimate genetic contributions to the etiology. At least 4% of patients with typical CP have disease-causing CNVs, and at least 14% have disease-causing single nucleotide variants or indels. The rate of pathogenic genomic lesions is probably more than twice as high among patients who have atypical CP, i.e., neuromotor dysfunction with additional neurodevelopmental abnormalities or malformations, or with MRI findings and medical history that are not characteristic of a perinatal insult. Mutations of many different genetic loci can produce a CP-like phenotype. The importance of genetic variants of minor effect and of epigenetic modifications in producing a multifactorial predisposition to CP is less clear. Recognizing the specific cause of CP in an affected individual is essential to providing optimal clinical management. An etiological diagnosis provides families an "enhanced compass" that improves overall well-being, facilitates access to educational and social services, permits accurate genetic counseling, and, for a subset of patients such as those with underlying inherited metabolic disorders, may make precision therapy that targets the pathophysiology available. Trio exome sequencing with assessment of copy number or trio genome sequencing with bioinformatics analysis for single nucleotide variants, indels, and copy number variants is clinically indicated in the initial workup of CP patients, especially those with additional malformations or neurodevelopmental abnormalities.

Clinical and biochemical footprints of inherited metabolic disease. V. Cerebral palsy phenotypes

Cerebral palsy is the most common physical disability of childhood describing a heterogeneous group of neurodevelopmental disorders that cause activity limitation, but often are accompanied by disturbances of sensation, perception, cognition, communication and behavior, or by epilepsy. Inborn errors of metabolism have been reported in the literature as presenting with features of cerebral palsy. We reviewed and updated the list of metabolic disorders known to be associated with symptoms suggestive of cerebral palsy and found more than 150 relevant IEMs. This represents the fifth of a series of articles attempting to create and maintain a comprehensive list of clinical and metabolic differential diagnosis according to system involvement.

Paralytic dislocation of the hip in children

Despite the progress made in the past decades, hip disorders are one of the most common orthopedic problems in the context of paralysis. The etiology can be congenital (malformation such as myelomeningoceles, genetic neuromuscular disorders) or acquired (cerebral palsy, post-traumatic). In these conditions, the orthopedic deformities are minimal at birth. They can develop as the child grows, at different ages, depending on the etiology, severity of the neuromuscular disorder and functional potential. Hip subluxation and dislocation can compromise standing and walking capacities, but also the quality of the seated position and the personal care. Daily life activities and participation are restricted and influence the disabled person's quality of life. Paralytic dislocation of the hip is the orthopedic deformity that has be biggest impact on day-to-day life, general health and the overall orthopedic result in adulthood. Neuro-orthopedic care is challenging. However, there are basic principles that one must know to ensure good long-term quality of life in patients suffering from paralytic dislocations of the hip. When planning the treatment strategy, it is essential to take into consideration the day-to-day life and to integrate the patient's experiences and needs, along with those of their caretakers. The objective of this review is to outline the differences in paralytic dislocations of the hip of diverse etiology, to present evaluation principles useful in daily clinical practice and to help practitioners in choosing a treatment strategy.

Using both electromyography and movement disorder assessment improved the classification of children with dyskinetic cerebral palsy

AIM

Children with dyskinetic cerebral palsy (CP) are often severely affected and effective treatment is difficult, due to different underlying disease mechanisms. Comprehensive systematic movement disorder evaluations were carried out on patients with this disorder.

METHODS

Patients born from 1995 to 2007 were identified from the Danish Cerebral Palsy Register and referrals to the neuropaediatric centre, Rigshospitalet, Copenhagen. They were classified by gross motor function, manual functional ability, communication ability, dystonia and spasticity. Electromyography was carried out on the upper and lower limbs. Magnetic resonance imaging scans were revised, and aetiological searches for underlying genetic disorders were performed.

RESULTS

We investigated 25 patients with dyskinetic CP at a mean age of 11.7 years. Dystonia, spasticity and rigidity were found in the upper limbs of 21, four and six children, respectively, and in the lower limbs of 18, 18 and three children. The mean total Burke-Fahn-Marsden score for dystonia was 45.02, and the mean Disability Impairment Scale level was 38% for dystonia and 13% for choreoathetosis. Sustained electromyography activity was observed in 20/25 children. Stretching increased electromyography activity more in children with spasticity. There were 10 re-classifications.

CONCLUSION

The children had heterogenic characteristics, and 40% were reclassified after systematic movement disorder evaluation.

Mendelian etiologies identified with whole exome sequencing in cerebral palsy

Objectives

Cerebral palsy (CP) is the most common childhood motor disability, yet its link to single‐gene disorders is under‐characterized. To explore the genetic landscape of CP, we conducted whole exome sequencing (WES) in a cohort of patients with CP.

Methods

We performed comprehensive phenotyping and WES on a prospective cohort of individuals with cryptogenic CP (who meet criteria for CP; have no risk factors), non‐cryptogenic CP (who meet criteria for CP; have at least one risk factor), and CP masqueraders (who could be diagnosed with CP, but have regression/progressive symptoms). We characterized motor phenotypes, ascertained medical comorbidities, and classified brain MRIs. We analyzed WES data using an institutional pipeline.

Results

We included 50 probands in this analysis (20 females, 30 males). Twenty‐four had cryptogenic CP, 20 had non‐cryptogenic CP, five had CP masquerader classification, and one had unknown classification. Hypotonic‐ataxic subtype showed a difference in prevalence across the classification groups (p = 0.01). Twenty‐six percent of participants (13/50) had a pathogenic/likely pathogenic variant in 13 unique genes (ECHS1, SATB2, ZMYM2, ADAT3, COL4A1, THOC2, SLC16A2, SPAST, POLR2A, GNAO1, PDHX, ACADM, ATL1), including one patient with two genetic disorders (ACADM, PDHX) and two patients with a SPAST‐related disorder. The CP masquerader category had the highest diagnostic yield (n = 3/5, 60%), followed by the cryptogenic CP category (n = 7/24, 29%). Fifteen percent of patients with non‐cryptogenic CP (n = 3/20) had a Mendelian disorder on WES.

Interpretation

WES demonstrated a significant prevalence of Mendelian disorders in individuals clinically diagnosed with CP, including in individuals with known CP risk factors.

Multi-Organ Dysfunction in Cerebral Palsy

Cerebral Palsy (CP) describes a heterogenous group of non-progressive disorders of posture or movement, causing activity limitation, due to a lesion in the developing brain. CP is an umbrella term for a heterogenous condition and is, therefore, descriptive rather than a diagnosis. Each case requires detailed consideration of etiology. Our understanding of the underlying cause of CP has developed significantly, with areas such as inflammation, epigenetics and genetic susceptibility to subsequent insults providing new insights. Alongside this, there has been increasing recognition of the multi-organ dysfunction (MOD) associated with CP, in particular in children with higher levels of motor impairment. Therefore, CP should not be seen as an unchanging disorder caused by a solitary insult but rather, as a condition which evolves over time. Assessment of multi-organ function may help to prevent complications in later childhood or adulthood. It may also contribute to an improved understanding of the etiology and thus may have an implication in prevention, interventional methods and therapies. MOD in CP has not yet been quantified and a scoring system may prove useful in allowing advanced clinical planning and follow-up of children with CP. Additionally, several biomarkers hold promise in assisting with long-term monitoring. Clinicians should be aware of the multi-system complications that are associated with CP and which may present significant diagnostic challenges given that many children with CP communicate non-verbally. A step-wise, logical, multi-system approach is required to ensure that the best care is provided to these children. This review summarizes multi-organ dysfunction in children with CP whilst highlighting emerging research and gaps in our knowledge. We identify some potential organ-specific biomarkers which may prove useful in developing guidelines for follow-up and management of these children throughout their lifespan.

Genetic Testing Contributes to Diagnosis in Cerebral Palsy: Aicardi-Goutières Syndrome as an Example

Cerebral palsy (CP) is a non-progressive neurodevelopmental disorder characterized by motor impairments, often accompanied by co-morbidities such as intellectual disability, epilepsy, visual and hearing impairment and speech and language deficits. Despite the established role of hypoxic–ischemic injury in some CP cases, several studies suggest that birth asphyxia is actually an uncommon cause, accounting for <10% of CP cases. For children with CP in the absence of traditional risk factors, a genetic basis to their condition is increasingly suspected. Several recent studies indeed confirm copy number variants and single gene mutations with large genetic heterogeneity as an etiology in children with CP. Here, we report three patients with spastic cerebral palsy and a genetically confirmed diagnosis of Aicardi-Goutières syndrome (AGS), with highly variable phenotypes ranging from clinically suggestive to non-specific symptomatology. Our findings suggest that AGS may be a rather common cause of CP, that frequently remains undiagnosed without additional genetic testing, as in only one case a clinical suspicion of AGS was raised. Our data show that a diagnosis of AGS must be considered in cases with spastic CP, even in the absence of characteristic brain abnormalities. Importantly, a genetic diagnosis of AGS may have significant therapeutic consequences, as targeted therapies are being developed for type 1 interferonopathies, the group of diseases to which AGS belongs. Our findings demonstrate the importance of next generation sequencing in CP patients without an identifiable cause, since targeted diagnostic testing is hampered by the often non-specific presentation.

The Role of Neuroimaging and Genetic Analysis in the Diagnosis of Children With Cerebral Palsy

Cerebral magnetic resonance imaging (MRI) is considered an important tool in the assessment of a child with cerebral palsy (CP), as it is abnormal in more than 80% of children with CP, disclosing the pathogenic pattern responsible for the neurological condition. MRI, therefore, is recommended as the first diagnostic step after medical history taking and neurological examination. With the advances in genetic diagnostics, the genetic contribution to CP is increasingly discussed, and the question arises about the role of genetic testing in the diagnosis of cerebral palsy. The paper gives an overview on genetic findings reported in CP, which are discussed with respect to the underlying brain pathology according to neuroimaging findings. Surveillance of Cerebral Palsy in Europe (SCPE) classifies neuroimaging findings in CP into five categories, which help to stratify decisions concerning genetic testing. Predominant white and gray matter injuries are by far predominant (accounting for around 50 and 20% of the findings). They are considered to be acquired. Here, predisposing genetic factors may play a role to increase vulnerability (and should especially be considered, when family history is positive and/or causative external factors are missing). In maldevelopments and normal findings (around 11% each), monogenic causes are more likely, and thus, genetic testing is clearly recommended. In the miscellaneous category, the precise nature of the MRI finding has to be considered as it could indicate a genetic origin.

Insights From Genetic Studies of Cerebral Palsy

Cohort-based whole exome and whole genome sequencing and copy number variant (CNV) studies have identified genetic etiologies for a sizable proportion of patients with cerebral palsy (CP). These findings indicate that genetic mutations collectively comprise an important cause of CP. We review findings in CP genomics and propose criteria for CP-associated genes at the level of gene discovery, research study, and clinical application. We review the published literature and report 18 genes and 5 CNVs from genomics studies with strong evidence of for the pathophysiology of CP. CP-associated genes often disrupt early brain developmental programming or predispose individuals to known environmental risk factors. We discuss the overlap of CP-associated genes with other neurodevelopmental disorders and related movement disorders. We revisit diagnostic criteria for CP and discuss how identification of genetic etiologies does not preclude CP as an appropriate diagnosis. The identification of genetic etiologies improves our understanding of the neurobiology of CP, providing opportunities to study CP pathogenesis and develop mechanism-based interventions.

A Proposed Diagnostic Algorithm for Inborn Errors of Metabolism Presenting With Movements Disorders

Inherited metabolic diseases or inborn errors of metabolism frequently manifest with both hyperkinetic (dystonia, chorea, myoclonus, ataxia, tremor, etc.) and hypokinetic (rigid-akinetic syndrome) movement disorders. The diagnosis of these diseases is in many cases difficult, because the same movement disorder can be caused by several diseases. Through a literature review, two hundred and thirty one inborn errors of metabolism presenting with movement disorders have been identified. Fifty-one percent of these diseases exhibits two or more movement disorders, of which ataxia and dystonia are the most frequent. Taking into account the wide range of these disorders, a methodical evaluation system needs to be stablished. This work proposes a six-step diagnostic algorithm for the identification of inborn errors of metabolism presenting with movement disorders comprising red flags, characterization of the movement disorders phenotype (type of movement disorder, age and nature of onset, distribution and temporal pattern) and other neurological and non-neurological signs, minimal biochemical investigation to diagnose treatable diseases, radiological patterns, genetic testing and ultimately, symptomatic, and disease-specific treatment. As a strong action, it is emphasized not to miss any treatable inborn error of metabolism through the algorithm.

Role of child neurologists and neurodevelopmentalists in the diagnosis of cerebral palsy: A survey study

OBJECTIVE

To contextualize the role of child neurologists and neurodevelopmentalists (CNs/NDDs) in cerebral palsy (CP) care, we review the changing landscape of CP diagnosis and survey stakeholder CNs/NDDs regarding their roles in CP care.

METHODS

The optimal roles of the multiple specialties involved in CP care are currently unclear, particularly regarding CP diagnosis. We developed recommendations regarding the role of CNs/NDDs noting (1) increasing complexity of CP diagnosis given a growing number of genetic etiologies and treatable motor disorders that can be misdiagnosed as CP and (2) the views of a group of physician stakeholders (CNs/NDDs from the Child Neurology Society Cerebral Palsy Special Interest Group).

RESULTS

CNs/NDDs felt that they were optimally suited to diagnose CP. Many (76%) felt that CNs/NDDs should always be involved in CP diagnosis. However, 42% said that their patients with CP were typically not diagnosed by CNs/NDDs, and 18% did not receive referrals to establish the diagnosis of CP at all. CNs/NDDs identified areas of their expertise critical for CP diagnosis including knowledge of the neurologic examination across development and early identification of features atypical for CP. This contrasts with their views on CP management, where CNs/NDDs felt that they could contribute to the medical team, but were necessary primarily when neurologic coexisting conditions were present.

DISCUSSION

Given its increasing complexity, we recommend early referral for CP diagnosis to a CN/NDD or specialist with comparable expertise. This contrasts with current consensus guidelines, which either do not address or do not recommend specific specialist referral for CP diagnosis.

Defining the clinical, molecular and imaging spectrum of adaptor protein complex 4-associated hereditary spastic paraplegia

Bi-allelic loss-of-function variants in genes that encode subunits of the adaptor protein complex 4 (AP-4) lead to prototypical yet poorly understood forms of childhood-onset and complex hereditary spastic paraplegia: SPG47 (AP4B1), SPG50 (AP4M1), SPG51 (AP4E1) and SPG52 (AP4S1). Here, we report a detailed cross-sectional analysis of clinical, imaging and molecular data of 156 patients from 101 families. Enrolled patients were of diverse ethnic backgrounds and covered a wide age range (1.0-49.3 years). While the mean age at symptom onset was 0.8 ± 0.6 years [standard deviation (SD), range 0.2-5.0], the mean age at diagnosis was 10.2 ± 8.5 years (SD, range 0.1-46.3). We define a set of core features: early-onset developmental delay with delayed motor milestones and significant speech delay (50% non-verbal); intellectual disability in the moderate to severe range; mild hypotonia in infancy followed by spastic diplegia (mean age: 8.4 ± 5.1 years, SD) and later tetraplegia (mean age: 16.1 ± 9.8 years, SD); postnatal microcephaly (83%); foot deformities (69%); and epilepsy (66%) that is intractable in a subset. At last follow-up, 36% ambulated with assistance (mean age: 8.9 ± 6.4 years, SD) and 54% were wheelchair-dependent (mean age: 13.4 ± 9.8 years, SD). Episodes of stereotypic laughing, possibly consistent with a pseudobulbar affect, were found in 56% of patients. Key features on neuroimaging include a thin corpus callosum (90%), ventriculomegaly (65%) often with colpocephaly, and periventricular white-matter signal abnormalities (68%). Iron deposition and polymicrogyria were found in a subset of patients. AP4B1-associated SPG47 and AP4M1-associated SPG50 accounted for the majority of cases. About two-thirds of patients were born to consanguineous parents, and 82% carried homozygous variants. Over 70 unique variants were present, the majority of which are frameshift or nonsense mutations. To track disease progression across the age spectrum, we defined the relationship between disease severity as measured by several rating scales and disease duration. We found that the presence of epilepsy, which manifested before the age of 3 years in the majority of patients, was associated with worse motor outcomes. Exploring genotype-phenotype correlations, we found that disease severity and major phenotypes were equally distributed among the four subtypes, establishing that SPG47, SPG50, SPG51 and SPG52 share a common phenotype, an 'AP-4 deficiency syndrome'. By delineating the core clinical, imaging, and molecular features of AP-4-associated hereditary spastic paraplegia across the age spectrum our results will facilitate early diagnosis, enable counselling and anticipatory guidance of affected families and help define endpoints for future interventional trials.

The Expanding Role of Genetics in Cerebral Palsy

Cerebral palsy is a clinical diagnosis of a nonprogressive developmental disorder of motor impairment. The scope of the diagnosis of cerebral palsy has been broadening significantly in recent years to include patients with genetic disorders. This article helps clinicians to determine which patients would benefit from a thorough genetic/metabolic evaluation and helps to delineate an approach for the work-up, with an emphasis on newer technologies and the evolving fields of fetal medicine and genetics. It provides guidance to providers to assist in clarifying an cause for some patient's symptoms.

Impacts of genomics on the health and social costs of intellectual disability

BACKGROUND

This study provides an integrated assessment of the economic and social impacts of genomic sequencing for the detection of monogenic disorders resulting in intellectual disability (ID).

METHODS

Multiple knowledge bases were cross-referenced and analysed to compile a reference list of monogenic disorders associated with ID. Multiple literature searches were used to quantify the health and social costs for the care of people with ID. Health and social expenditures and the current cost of whole-exome sequencing and whole-genome sequencing were quantified in relation to the more common causes of ID and their impact on lifespan.

RESULTS

On average, individuals with ID incur annual costs in terms of health costs, disability support, lost income and other social costs of US$172 000, accumulating to many millions of dollars over a lifetime.

CONCLUSION

The diagnosis of monogenic disorders through genomic testing provides the opportunity to improve the diagnosis and management, and to reduce the costs of ID through informed reproductive decisions, reductions in unproductive diagnostic tests and increasingly targeted therapies.

Cerebral Palsy: Current Opinions on Definition, Epidemiology, Risk Factors, Classification and Treatment Options

Cerebral palsy (CP) is one of the most frequent causes of motor disability in children. According to the up-to-date definition, CP is a group of permanent disorders of the development of movement and posture, causing activity limitations that are attributed to non-progressive disturbances that occurred in the developing foetal or infant brain. The CP definition has evolved over time; the problem is aetiologically and clinically very heterogeneous. According to European data, the average frequency of CP is 2.08 per 1000 live births, but in the group of children born with a body weight below 1500 g, the frequency is 70 times higher when compared with the group of children with a body weight over 2500 g at birth. The risk factors for CP can be divided into pre-conception, prenatal, perinatal and postnatal ones. CP commonly co-exists with epilepsy, in particular drug-resistant epilepsy, but also with mental retardation, visual and hearing impairment, as well as feeding and behavioral disorders. The degree of motor problem varies from mild to very severe making the child totally dependent on caregivers. Cerebral palsy is divided into forms depending on the type of motor disorders which dominate the clinical presentation; the traditional classifications by Ingram and Hagberg have now been replaced by the Surveillance of Cerebral Palsy in Europe classification which divides CP into spastic, dyskinetic and ataxic forms. Although cerebral palsy is a clinical diagnosis, modern diagnostic imaging provides information that allows the division of the results of magnetic resonance imaging in children with cerebral palsy into five groups according to the magnetic resonance imaging classification system. Just as the clinical presentation and the factors predisposing for CP are very diverse, treatment is also a very complex problem. Modern treatment of spasticity includes both botulinum toxin therapies and surgical techniques, eg, rhizotomy. The authors present current views on definitions, risk factors, diagnostics and treatment of CP as well as comorbid problems, eg, drug-resistant epilepsy.

Losing a diagnosis of cerebral palsy: a comparison of variables at 2 and 5 years

AIM

This study aims to identify characteristics at 2 years of age that differ between children with confirmed cerebral palsy (CP) and a non-CP diagnosis by 5 years of age.

METHOD

This was a retrospective cohort analysis. A CP diagnosis may be considered a 'probable' diagnosis at 2 years, which is often 'confirmed' at 4 or 5 years, particularly in the context of CP registries. A total of 1683 children with a diagnosis of CP or probable CP at 2 years of age were identified from the Canadian Cerebral Palsy Registry, of whom 48 received a non-CP diagnosis at 5 years ('non-confirmed CP'). Perinatal adversity, preterm birth status, Gross Motor Function Classification System (GMFCS) level, presence of comorbidities, magnetic resonance imaging (MRI) findings, and initial CP motor type were compared between the two groups by univariate and logistic regression analyses.

RESULTS

χ² analysis and multivariate analysis both confirmed that children with a non-CP diagnosis by 5 years of age were more likely to have a normal MRI (χ² odds ratio [OR]=7.8, 95% confidence interval [CI]=3.8-16.1; OR=5.4, 95% CI=2.4-12.5), ataxic-hypotonic (χ² OR=10.1, 95% CI=4.9-21.2; OR=6.1, 95% CI=2.2-16.2) or dyskinetic CP (χ² OR=2.7, 95% CI=1.2-5.9; OR=2.9, 95% CI=1.0-7.6), born at term (χ² OR=3.7, 95% CI=1.7-8.0; OR=3.6, 95% CI=1.0-12.1), and lack perinatal adversity (χ² OR=4.1, 95% CI=1.6-10.7; OR=3.4, 95% CI=1.0-11.7).

INTERPRETATION

Normal MRI, ataxic-hypotonic or dyskinetic CP, lack of perinatal adversity, and term birth are associated with a higher odds of non-CP diagnosis by 5 years of age, thus potentially enhancing diagnostic work-up.

WHAT THIS PAPER ADDS

Normal magnetic resonance imaging (MRI) at 2 years was associated with a non-cerebral palsy (CP) diagnosis by 5 years. Diagnosis of ataxic-hypotonic or dyskinetic CP motor subtype at 2 years was associated with a non-CP diagnosis by 5 years. Perinatal adversity and preterm birth were rarer with a non-CP diagnosis by 5 years.

Metabolic and genetic disorders mimicking cerebral palsy

Cerebral palsy is a syndrome that encompasses a large group of childhood movement and posture disorders that result from a lesion occurring in the developing brain. The clinical presentation of many metabolic and genetic conditions, particularly in highly consanguineous populations, can mimic cerebral palsy particularly at early age. The aim of this review article is to identify the clinical features that should alert the physician to the possibility of disorders that resemble cerebral palsy, the clinical and neuroimaging red flags, and highlight some metabolic and genetic conditions which may present with spasticity, ataxia and dyskinesia. In the case of metabolic or genetic disorder, making a precise diagnosis is particularly important for the possibility of treatment, accurate prognosis and genetic counseling.

Genetic or Other Causation Should Not Change the Clinical Diagnosis of Cerebral Palsy

High throughput sequencing is discovering many likely causative genetic variants in individuals with cerebral palsy. Some investigators have suggested that this changes the clinical diagnosis of cerebral palsy and that these individuals should be removed from this diagnostic category. Cerebral palsy is a neurodevelopmental disorder diagnosed on clinical signs, not etiology. All nonprogressive permanent disorders of movement and posture attributed to disturbances that occurred in the developing fetal and infant brain can be described as "cerebral palsy." This definition of cerebral palsy should not be changed, whatever the cause. Reasons include stability, utility and accuracy of cerebral palsy registers, direct access to services, financial and social support specifically offered to families with cerebral palsy, and community understanding of the clinical diagnosis. Other neurodevelopmental disorders, for example, epilepsy, have not changed the diagnosis when genomic causes are found. The clinical diagnosis of cerebral palsy should remain, should prompt appropriate genetic studies and can subsequently be subclassified by etiology.

Profile of children with cerebral palsy spectrum disorder and a normal MRI study

OBJECTIVE

This study looks at what profile can be expected in children with cerebral palsy spectrum disorder (CP) and a normal MRI.

METHODS

The data were excerpted from the Canadian Cerebral Palsy Registry database. Only patients who had undergone MRI were included in the analysis. Neuroimaging classification was ascertained by university-based pediatric neuroradiologists and split into 2 categories: normal and abnormal MRIs. Six factors were then compared between those 2 groups: prematurity, perinatal adversity, presence of more than 1 comorbidity, CP subtype, bimanual dexterity (Manual Ability Classification System [MACS]), and gross motor function (Gross Motor Function Classification System [GMFCS]).

RESULTS

Participants with no perinatal adversity were 5.518 times more likely to have a normal MRI (p < 0.0001, 95% confidence interval [CI] 4.153-7.330). Furthermore, participants with dyskinetic, ataxic/hypotonic, and spastic diplegic forms of CP were 2.045 times more likely to have a normal MRI than those with hemiplegia, triplegia, and quadriplegia (p < 0.0001, 95% CI 1.506-2.778). No significant difference was found in prematurity, GMFCS levels, MACS levels, and the number of comorbidities.

CONCLUSIONS

Normal MRIs were associated with lack of perinatal adversity as well as with the dyskinetic, ataxic/hypotonic, and spastic diplegic CP subtypes. As MRI normality is not strongly associated with the severity of CP, continuous follow-up in children with normal imaging appears warranted. Further advanced imaging modalities, as well as strong consideration for metabolic and genetic testing, may provide additional insights into causal pathways in this population.

The genetic etiology in cerebral palsy mimics: The results from a Greek tertiary care center

OBJECTIVE

Non-progressive genetic disorders may present with motor dysfunction resembling cerebral palsy (CP). Such patients are often characterized as CP mimics. The purpose of this work was to delineate the clinical manifestations and molecular findings of CP mimic patients, with the ultimate goal to offer specific disease-modifying therapy and genetic counseling.

METHODS

Retrospective study of 47 patients diagnosed with CP and no acquired etiology. Chart review of clinical, neuroradiological, biochemical and molecular data was performed.

RESULTS

31,91% of patients manifested with features resembling dyskinetic CP, 19,14% spastic CP, 10,63% ataxic CP and 38,30% mixed CP. In 23 patients molecular diagnosis was reached and included 5 hereditary spastic paraplegia genes (SPG) in spastic CP mimics; HPRT1, TH, QDPR, DDC in dystonic CP mimics; ADCY5 and NIKX2-1 in choreic CP mimics; CANA1A in ataxic CP mimics; and SPG, PDHA1, NIKX2-1, AT, SLC2A1 and SPR in mixed CP mimics. In 14 patients, the etiological diagnosis led to specific treatment.

CONCLUSIONS

CP mimics show a number of features that differ from classic CP and can be used as diagnostic clues, including presence of mixed motor features, minor dysmorphic features, oculogyric movements, multiple features of autonomic dysfunction, and acquired microcephaly. A more stringent use of the concept of CP focused on acquired lesions during the perinatal and infancy periods, and excluding disorders that could be of genetic origin, could contribute to a purer use of the term. Identification of a specific genetic cause for CP mimics may in certain cases lead to etiologic treatment.

Current therapies and therapeutic decision making for childhood-onset movement disorders

Movement disorders differ in children to adults. First, neurodevelopmental movement disorders such as tics and stereotypies are more prevalent than parkinsonism, and second, there is a genomic revolution which is now explaining many early-onset dystonic syndromes. We outline an approach to children with movement disorders starting with defining the movement phenomenology, determining the level of functional impairment due to abnormal movements, and screening for comorbid psychiatric conditions and cognitive impairments which often contribute more to disability than the movements themselves. The rapid improvement in our understanding of the etiology of movement disorders has resulted in an increasing focus on precision medicine, targeting treatable conditions and defining modifiable disease processes. We profile some of the key disease-modifying therapies in metabolic, neurotransmitter, inflammatory, and autoimmune conditions and the increasing focus on gene or cellular therapies. When no disease-modifying therapies are possible, symptomatic therapies are often all that is available. These classically target dopaminergic, cholinergic, alpha-adrenergic, or GABAergic neurochemistry. Increasing interest in neuromodulation has highlighted that some clinical syndromes respond better to DBS, and further highlights the importance of "disease-specific" therapies with a future focus on individualized therapies according to the genomic findings or disease pathways that are disrupted. We summarize some pragmatic applications of symptomatic therapies, neuromodulation techniques, and some rehabilitative interventions and provide a contemporary overview of treatment in childhood-onset movement disorders. © 2019 International Parkinson and Movement Disorder Society.

Genetic mimics of cerebral palsy

The term "cerebral palsy mimic" is used to describe a number of neurogenetic disorders that may present with motor symptoms in early childhood, resulting in a misdiagnosis of cerebral palsy. Cerebral palsy describes a heterogeneous group of neurodevelopmental disorders characterized by onset in infancy or early childhood of motor symptoms (including hypotonia, spasticity, dystonia, and chorea), often accompanied by developmental delay. The primary etiology of a cerebral palsy syndrome should always be identified if possible. This is particularly important in the case of genetic or metabolic disorders that have specific disease-modifying treatment. In this article, we discuss clinical features that should alert the clinician to the possibility of a cerebral palsy mimic, provide a practical framework for selecting and interpreting neuroimaging, biochemical, and genetic investigations, and highlight selected conditions that may present with predominant spasticity, dystonia/chorea, and ataxia. Making a precise diagnosis of a genetic disorder has important implications for treatment, and for advising the family regarding prognosis and genetic counseling. © 2019 International Parkinson and Movement Disorder Society.

Secondary Abnormal CSF Neurotransmitter Metabolite Profiles in a Pediatric Tertiary Care Centre

BACKGROUND

Secondary neurotransmitter deficiencies have been reported in several reviews. Our primary aim was to assess the relationship among epilepsy, antiseizure medications, and specific neurotransmitter abnormalities. We also evaluated movement disorders and brain abnormalities via magnetic resonance imaging scans in patients with secondary neurotransmitter defects.

METHODS

This is a retrospective case series of 376 patients who underwent neurotransmitter analysis at BC Children's Hospital between 2009 and 2013, for a variety of neurological presentations. The biochemical genetics laboratory database was interrogated for results of cerebrospinal fluid neurotransmitter analyses. Clinical data for patients with abnormal results were collected from the hospital charts. Statistical analysis included one-way analysis of variance, chi-square, and a two-way contingency table.

RESULTS

Abnormal neurotransmitter values were identified in 67 (17.8%) patients, two (0.53%) of which were attributable to a congenital neurotransmitter disorder and 11 (16.9%) secondary to other genetic diagnoses. Of 64 patients with secondary abnormal neurotransmitter values, 38 (59%) presented with epilepsy and 20 (31%) with movement disorders. A combination of epilepsy and movement disorder was less frequent.

DISCUSSION

Acknowledging the limitations of this retrospective chart review, we conclude that, in our cohort, in addition to patients with movement disorders, a considerable number of patients with epilepsy and epileptic encephalopathy also showed secondary neurotransmitter mono-amine abnormalities. There is no clear relation, however, between clinical phenotype and type of neurotransmitter affected. In addition, no association was identified between the type of antiseizure medications and affected neurotransmitter type. We outline the need for prospective studies to further enrich our understanding of the relation between epilepsy and neurotransmitters with a focus on improving treatments and patient outcomes.

Inborn errors of metabolism

Inborn errors of metabolism, also known as inherited metabolic diseases, constitute an important group of conditions presenting with neurologic signs in newborns. They are individually rare but collectively common. Many are treatable through restoration of homeostasis of a disrupted metabolic pathway. Given their frequency and potential for treatment, the clinician should be aware of this group of conditions and learn to identify the typical manifestations of the different inborn errors of metabolism. In this review, we summarize the clinical, laboratory, electrophysiologic, and neuroimaging findings of the different inborn errors of metabolism that can present with florid neurologic signs and symptoms in the neonatal period.

Sine causa tetraparesis: A pilot study on its possible relationship with interferon signature analysis and Aicardi Goutières syndrome related genes analysis

Tetraparesis is usually due to cerebral palsy (CP), inborn errors of metabolism, neurogenetic disorders and spinal cord lesions. However, literature data reported that about 10% of children with tetraparesis show a negative/non-specific neuroradiological findings without a specific etiological cause. Aicardi Goutières Syndrome (AGS) is a genetic encephalopathy that may cause tetraparesis. Interferon signature is a reliable biomarker for AGS and could be performed in sine-causa tetraparesis. The aim of the study was to examine the type I interferon signature and AGS related-genes in children with sine causa tetraparesis, to look for misdiagnosed AGS. A secondary aim was to determine which aspects of the patient history, clinical picture and brain imaging best characterize tetraparesis due to an interferonopathy.Seven out of 78 patients affected by tetraparesis, characterized by unremarkable pre-peri-postnatal history and normal/non-specific brain magnetic resonance imaging (MRI) were selected and underwent anamnestic data collection, clinical examination, brain imaging review, peripheral blood interferon signature and AGS-related genes analysis.At our evaluation time (mean age of 11.9 years), all the 7 patients showed spastic-dystonic tetraparesis. At clinical onset brain MRI was normal in 4 and with non-specific abnormalities in 3; at follow-up 3 patients presented with new white-matter lesions, associated with brain calcification in 1 case. Interferon signature was elevated in one subject who presented also a mutation of the IFIH1 gene.AGS should be considered in sine-causa tetraparesis. Core features of interferonopathy-related tetraparesis are: onset during first year of life, psychomotor regression with tetraparesis evolution, brain white-matter lesions with late calcifications. A positive interferon signature may be a helpful marker to select patients with spastic tetraparesis who should undergo genetic analysis for AGS.

The complex aetiology of cerebral palsy

Cerebral palsy (CP) is the most prevalent, severe and costly motor disability of childhood. Consequently, CP is a public health priority for prevention, but its aetiology has proved complex. In this Review, we summarize the evidence for a decline in the birth prevalence of CP in some high-income nations, describe the epidemiological evidence for risk factors, such as preterm delivery and fetal growth restriction, genetics, pregnancy infection and other exposures, and discuss the success achieved so far in prevention through the use of magnesium sulfate in preterm labour and therapeutic hypothermia for birth-asphyxiated infants. We also consider the complexities of disentangling prenatal and perinatal influences, and of establishing subtypes of the disorder, with a view to accelerating the translation of evidence into the development of strategies for the prevention of CP.

Evaluation of the Child With Developmental Impairments

PURPOSE OF REVIEW

This article discusses the diagnostic evaluation of intellectual developmental disorder, comprising global developmental delay and intellectual disability in children.

RECENT FINDINGS

With a prevalence of 1% to 3% and substantial comorbidity, high lifetime costs, and emotional burden, intellectual developmental disorder is characterized by limitations in both intellectual functioning (IQ less than 70) and adaptive behavior starting before 18 years of age. Pinpointing the precise genetic cause is important, as it allows for accurate genetic counseling, avoidance of unnecessary testing, prognostication, and tailored management, which, for an increasing number of genetic conditions, targets the pathophysiology and improves outcomes.

SUMMARY

The etiology of intellectual developmental disorder is heterogeneous, which mandates a structured approach that considers family situation, test costs, yield, and potential therapeutic tractability of the identified condition. Diagnosis of an underlying genetic cause is increasingly important with the advent of new treatments. Still, in many cases, the cause remains unknown, and research is needed to elucidate its complex molecular basis.

The role of the clinician in the multi-omics era: are you ready?

Since Garrod's first description of alkaptonuria in 1902, and newborn screening for phenylketonuria introduced in the 1960s, P4 medicine (preventive, predictive, personalized, and participatory) has been a reality for the clinician serving patients with inherited metabolic diseases. The era of high-throughput technologies promises to accelerate its scale dramatically. Genomics, transcriptomics, epigenomics, proteomics, glycomics, metabolomics, and lipidomics offer an amazing opportunity for holistic investigation and contextual pathophysiologic understanding of inherited metabolic diseases for precise diagnosis and tailored treatment. While each of the -omics technologies is important to systems biology, some are more mature than others. Exome sequencing is emerging as a reimbursed test in clinics around the world, and untargeted metabolomics has the potential to serve as a single biochemical testing platform. The challenge lies in the integration and cautious interpretation of these big data, with translation into clinically meaningful information and/or action for our patients. A daunting but exciting task for the clinician; we provide clinical cases to illustrate the importance of his/her role as the connector between physicians, laboratory experts and researchers in the basic, computer, and clinical sciences. Open collaborations, data sharing, functional assays, and model organisms play a key role in the validation of -omics discoveries. Having all the right expertise at the table when discussing the diagnostic approach and individualized management plan according to the information yielded by -omics investigations (e.g., actionable mutations, novel therapeutic interventions), is the stepping stone of P4 medicine. Patient participation and the adjustment of the medical team's plan to his/her and the family's wishes most certainly is the capstone. Are you ready?

Early neonatal Glutaric aciduria type I hidden by perinatal asphyxia: a case report

Background

Perinatal asphyxia (PA) occurs in about 2 to 10 per 1000 live full-term births. Although neonatal epileptic seizures are observed in up to 60% of cases, PA may mimic or subtend other conditions. Hypoxia related brain injury is particularly relevant, as it may have permanent effects on neuropsychomotor development. Antepartum obstetric conditions, may, in turn, lead to hypoxic-ischemic damage to the fetus and the newborn, often underlying PA. Herein, a case of PA that hid and triggered signs and symptoms of Glutaric Aciduria type I (GA-I), is reported.

Case presentation

R.F. was born at term after prolonged labour, by induced vaginal delivery with the Kristeller manoeuvre. He presented with severe asphyxia and asystoly. Immediate cardiopulmonary resuscitation promptly restored cardiorespiratory parameters, allowing for early extubation 30 min after. During the following hours, severe axial muscle hypotonia with an increased tone of the limb extensor muscles became evident. The absence of crying and archaic reflexes persisted and there was an onset of generalized tonic or clonic seizure. First level metabolic and inflammatory markers were within the normal range. An inherited metabolic disease was then suspected, due to the persistent clinical signs of severe neurological damage without any detectable septic parameter. GA-I was assessed and specific treatment started without any clinical improvement, although ensuring adequate growth and metabolic control. Thereafter, the baby developed a severe encephalopathy with drug resistant epileptic seizures. The progression of the neurological damage and a CVC-related sepsis led him to exitus at 2 years.

Conclusions

To the best of our knowledge, this is the first case of early post-natal onset of GA-I reported in literature to date, in the absence of expanded newborn screening (NBS) programme. As expanded NBS programmes for inborn errors of metabolism have not yet been internationally adopted, we are of the opinion that such diseases may well be hidden by misleading signs and symptoms imputable to other more frequent harmful clinical conditions. Moreover, it would be advisable that neonatologists be trained to include GA-I in the differential diagnosis of neurological damage secondary to PA.

The Team-Based Approach to Undiagnosed and Rare Diseases

Patients with undiagnosed or rare diseases often remain without a diagnosis for many years. Many are misdiagnosed or treated symptomatically without having an identified underlying disease process. Health care providers in general practice and subspecialists are equipped to diagnose diseases commonly seen. Most practitioners are unlikely to be familiar with uncommon manifestations of a common disorder and have little or no experience with rare diseases. Multidisciplinary teams are effective in reviewing patients with undiagnosed and rare diseases and in developing a new diagnostic strategy for appropriate evaluation. A medical librarian and an access coordinating navigator are essential members of the team.

Treatment of Neurogenetic Developmental Conditions: From 2016 into the Future

BACKGROUND

Neurogenetic developmental conditions represent a heterogeneous group of rare inherited disorders with neurological manifestation during development. Treatments for these conditions have largely been supportive; however, a number of treatments are emerging which target the underlying physiology and offer great potential. Our aim was to present a state-of-the-art overview of the current and potential causal treatments available or under development for neurogenetic developmental conditions.

METHODS

In this review, we focus on the following neurogenetic developmental conditions: (1) inborn errors of metabolism causing neurogenetic developmental conditions, (2) fragile X syndrome, (3) Rett syndrome, (4) tuberous sclerosis complex, 5) Down syndrome and other neurogenetic developmental conditions.

RESULTS

A large group of inborn errors of metabolism leads to neurodevelopmental disability, affecting the central nervous system during infancy or childhood and can present with comorbidities such as intellectual developmental disability, epilepsy, atypical cerebral palsy, autism spectrum disorder, behavioral and psychiatric disturbances, for which causal treatments are discussed.

CONCLUSIONS

The advent of these new disease-modifying therapies has the potential to reverse the underlying neural mechanisms of these debilitating conditions, which may provide prospect to affected individuals.

Neurometabolic disorders are treatable causes of dystonia

A broad range of rare inherited metabolic disorders can present with dystonia. For clinicians, it is important to recognize dystonic features, but it can be complicated by the mixed and complex clinical picture seen in many neurometabolic patients. Careful phenotyping is the first step towards the diagnosis of the underlying condition and subsequent targeted treatment, further supported by imaging, biochemical diagnostics and the availability of modern diagnostic techniques such as next generation sequencing. As several neurometabolic disorders are treatable causes of dystonia, these should have priority in the diagnostic process. In the symptomatic treatment of dystonia, several therapeutic options are available. Awareness for the occurrence and optimal treatment of dystonia and other movement disorders in neurometabolic conditions is important because these symptoms can have a substantial impact on the quality of life and daily functioning; this effect is not only exerted by the dystonia itself, but also by the frequently associated non-motor features. In this paper, the highlights and key concepts of neurometabolic forms of dystonia are discussed, with a focus on phenomenology, the diagnostic approach, the most important neurometabolic aetiologies, co-occurring non-motor features and therapeutic options.

Cerebral palsy: causes, pathways, and the role of genetic variants

Cerebral palsy (CP) is heterogeneous with different clinical types, comorbidities, brain imaging patterns, causes, and now also heterogeneous underlying genetic variants. Few are solely due to severe hypoxia or ischemia at birth. This common myth has held back research in causation. The cost of litigation has devastating effects on maternity services with unnecessarily high cesarean delivery rates and subsequent maternal morbidity and mortality. CP rates have remained the same for 50 years despite a 6-fold increase in cesarean birth. Epidemiological studies have shown that the origins of most CP are prior to labor. Increased risk is associated with preterm delivery, congenital malformations, intrauterine infection, fetal growth restriction, multiple pregnancy, and placental abnormalities. Hypoxia at birth may be primary or secondary to preexisting pathology and international criteria help to separate the few cases of CP due to acute intrapartum hypoxia. Until recently, 1-2% of CP (mostly familial) had been linked to causative mutations. Recent genetic studies of sporadic CP cases using new-generation exome sequencing show that 14% of cases have likely causative single-gene mutations and up to 31% have clinically relevant copy number variations. The genetic variants are heterogeneous and require function investigations to prove causation. Whole genome sequencing, fine scale copy number variant investigations, and gene expression studies may extend the percentage of cases with a genetic pathway. Clinical risk factors could act as triggers for CP where there is genetic susceptibility. These new findings should refocus research about the causes of these complex and varied neurodevelopmental disorders.