Treatable metabolic psychoses that go undetected: what Niemann-Pick type C can teach us

Eine Kinderkrankheit wird erwachsen

Zusammenfassung: Die Untersuchung von seltenen Erkrankungen ist aufgrund der geringen Anzahl an Patient_innen sowie einem häufig heterogenen, multisymptomatischen Erscheinungsbild deutlich erschwert. Als Beispiel für eine solche seltene Krankheit dient im Folgenden die progrediente, neurodegenerative Erbkrankheit Niemann-Pick Typ C (NPC), die lange Zeit als „Kinderkrankheit“ galt. Im Verlauf des letzten Jahrzehnts wurde jedoch auch ein substanzieller Anteil an erwachsenen NPC-Patient_innen diagnostiziert. Da zum klinischen Erscheinungsbild von erwachsenen NPC-Patient_innen wenig Umfassendes bekannt ist, widmet sich der Artikel diesem Thema und zeigt, inwieweit die Erkenntnisse zu Manifestationen sowie zur Krankheitsentwicklung von pädiatrischen auf erwachsene NPC-Patient_innen übertragbar sind. Die Darstellung von Erkrankungsmerkmalen der Subpopulationen pädiatrischer gegenüber jugendlicher bzw. erwachsener NPC-Patient_innen basiert auf der verfügbaren Literatur sowie Expertenmeinungen hinsichtlich der Epidemiologie, des genetischen Mutationsmusters, des klinischen Bildes einschließlich der Prodromalsymptome, der Progressionsrate, dem allgemeinen Behandlungsregime und den Therapieeffekten. Insgesamt erweist sich NPC als ein Krankheitskontinuum, basierend auf weitestgehend ähnlichen genetischen Mutationsmustern sowie einer sich in den Altersgruppen entsprechenden Pathophysiologie. Pädiatrische und jugendliche bzw. erwachsene Patient_innen sind durch diverse Facetten fortschreitender neuropsychologischer Manifestationen wie bspw. kognitive Defizite und deutliche Einschränkungen ihrer motorischen Fähigkeiten (einschließlich der Berücksichtigung von prodromalen Symptomen) gekennzeichnet. NPC verläuft bei Kindern sowie bei jugendlichen bzw. erwachsenen Patient_innen auf die ähnliche Weise – jedoch mit einer beschleunigten Progressionsrate und einer somit verkürzten Lebenserwartung, je jünger die Patient_innen bei erstmaligem Auftreten neurologischer Symptome sind. Jedoch weist die hohe Krankheitslast aller NPC-Patient_innen auf die Schwere dieser seltenen Stoffwechselkrankheit hin. Die Behandlung von NPC erfolgt altersunabhängig interdisziplinär. Es besteht bisher keine kausale Therapieoption.

Psychosis symptoms associated with Niemann-Pick disease type C

Niemann-Pick disease type C (NP-C) is a severe neurovisceral lipid storage disease that results in the accumulation of unesterified cholesterol in lysosomes or endosomes. The clinical presentations of NP-C are variable which include visceral symptoms, neurologic symptoms and psychiatric symptoms. Psychosis is the most common psychiatric manifestation of NP-C and is indistinguishable from a typical psychosis presentation of schizophrenia. The common psychotic presentations in NP-C include visual hallucinations, delusions, auditory hallucinations and thought disorders. Psychosis symptoms are more common in adult or adolescent-onset forms compared with pediatric-onset forms. The underlying pathophysiology of psychosis in NP-C is most probably due to dysconnectivity particularly between frontotemporal connectivity and subcortical structures. NP-C sometimes is mistaken for schizophrenia which causes delay in treatment due to lack of awareness and literature review. This review aims to summarize the relevant case reports on psychosis symptoms in NP-C and discuss the genetics and pathophysiology underlying the condition.

Screening for inborn errors of metabolism in psychotic patients using Next Generation Sequencing

Inborn errors of metabolism (IEMs) are a group of rare genetic disorders which, when emerging later in life, are often characterized by neuropsychiatric manifestations including psychosis. This study aimed to determine whether it would be useful to screen patients presenting with a psychotic disorder for IEMs by a single blood sample using Next Generation Sequencing (NGS), in order to detect rare, treatable causes of psychotic disorders. Blood was drawn from 60 patients with a psychotic disorder, with a duration of illness of less than 5 years. Blood samples were screened for 67 genes using NGS (Illumina® MiSeq sequencing technique). The results were compared to the human reference genome (GoNL, n = 498). The identified variants were classified according to the ACMG classification. For the psychotic patients, 6 variants of a likely pathogenic (class 4, n = 2) or pathogenic (class 5, n = 4) origin were found. As all variants were heterozygous, no patients were considered to be affected by an IEM. For the GoNL control group, 73 variants of a likely pathogenic (class 4, n = 31) or pathogenic (class 5, n = 42) origin were found. All of these found variants were heterozygous. Therefore, these individuals from the control group were considered to be a carrier only. Thus, no patients were identified to have an IEM as an underlying disease using this approach. However, NGS may be useful to detect variants of genes associated with IEMs in an enriched subgroup of psychotic patients.

The psychopharmacology of Wilson disease and other metabolic disorders

Wilson disease (WD) is a hereditary metabolic disorder (HMD) caused by a mutation in the copper-transporting gene ATP7B affecting the liver and central nervous system. About 30% of patients with WD may initially present with psychiatric symptoms, and management can be difficult. More generally, HMDs are a rare but important cause of psychiatric disorders in adolescents and adults. Main signs of HMDs may remain isolated for years before the appearance of hepatic or neurologic signs. The incidence of HMDs has been estimated at approximately 40 cases per 100,000 live births. Some of them are treatable and new diagnostic methods and therapies have become available. HMDs that present purely with psychiatric symptoms are very difficult to diagnose due to low awareness of these rare diseases among psychiatrists and neurologists. However, it is important to identify HMDs in order to provide disease-specific treatment and possible prevention of irreversible physical and neurologic complications. Genetic counseling can also be provided. Psychotropic medications should be prescribed carefully in that indication. This chapter focuses on three HMD categories: chronic, treatable HMDs (e.g., WD); acute, treatable HMDs; and chronic HMDs that are difficult to treat. In this review we focus on the psychopharmacology of WD and other chronic and difficult-to-treat HMDs. We provide some keys to take into account the main side effects associated with common psychotropic medications.

Psychiatric and neurological symptoms in patients with Niemann-Pick disease type C (NP-C): Findings from the International NPC Registry

Objectives: Niemann-Pick disease type C (NP-C) is a rare inherited neurovisceral disease that should be recognised by psychiatrists as a possible underlying cause of psychiatric abnormalities. This study describes NP-C patients who had psychiatric manifestations at enrolment in the international NPC Registry, a unique multicentre, prospective, observational disease registry. Methods: Treating physicians' data entries describing psychiatric manifestations in NPC patients were coded and grouped by expert psychiatrists. Results: Out of 386 NP-C patients included in the registry as of October 2015, psychiatric abnormalities were reported to be present in 34% (94/280) of those with available data. Forty-four patients were confirmed to have identifiable psychiatric manifestations, with text describing these psychiatric manifestations. In these 44 patients, the median (range) age at onset of psychiatric manifestations was 17.9 years (2.5-67.9; n = 15), while the median (range) age at NP-C diagnosis was 23.7 years (0.2-69.8; n = 34). Almost all patients (43/44; 98%) had an occurrence of ≥1 neurological manifestation at enrolment. Conclusions: These data show that substantial delays in diagnosis of NP-C are long among patients with psychiatric symptoms and, moreover, patients presenting with psychiatric features and at least one of cognitive impairment, neurological manifestations, and/or visceral symptoms should be screened for NP-C.

Systematic review of psychiatric signs in Niemann-Pick disease type C

Objectives: We conducted the first systematic literature review and analysis of psychiatric manifestations in Niemann-Pick disease type C (NPC) to describe: (1) time of occurrence of psychiatric manifestations relative to other disease manifestations; and (2) frequent combinations of psychiatric, neurological and visceral disease manifestations. Methods: A systematic EMBase literature search was conducted to identify, collate and analyze published data from patients with NPC associated with psychiatric symptoms, published between January 1967 and November 2015. Results: Of 152 identified publications 40 were included after screening that contained useable data from 58 NPC patients (mean [SD] age at diagnosis of NPC 27.8 [15.1] years). Among patients with available data, cognitive, memory and instrumental impairments were most frequent (90% of patients), followed by psychosis (62%), altered behavior (52%) and mood disorders (38%). Psychiatric manifestations were reported before or at neurological disease onset in 41 (76%) patients; organic signs (e.g., hepatosplenomegaly, hearing problems) were reported before psychiatric manifestations in 12 (22%). Substantial delays to diagnosis were observed (5-6 years between psychiatric presentation and NPC diagnosis). Conclusions: NPC should be considered as a possible cause of psychiatric manifestations in patients with an atypical disease course, acute-onset psychosis, treatment failure, and/or certain combinations of psychiatric/neurological/visceral symptoms.

The hidden Niemann-Pick type C patient: clinical niches for a rare inherited metabolic disease

BACKGROUND

Niemann-Pick disease type C (NP-C) is a rare, inherited neurodegenerative disease of impaired intracellular lipid trafficking. Clinical symptoms are highly heterogeneous, including neurological, visceral, or psychiatric manifestations. The incidence of NP-C is under-estimated due to under-recognition or misdiagnosis across a wide range of medical fields. New screening and diagnostic methods provide an opportunity to improve detection of unrecognized cases in clinical sub-populations associated with a higher risk of NP-C. Patients in these at-risk groups ("clinical niches") have symptoms that are potentially related to NP-C, but go unrecognized due to other, more prevalent clinical features, and lack of awareness regarding underlying metabolic causes.

METHODS

Twelve potential clinical niches identified by clinical experts were evaluated based on a comprehensive, non-systematic review of literature published to date. Relevant publications were identified by targeted literature searches of EMBASE and PubMed using key search terms specific to each niche. Articles published in English or other European languages up to 2016 were included.

FINDINGS

Several niches were found to be relevant based on available data: movement disorders (early-onset ataxia and dystonia), organic psychosis, early-onset cholestasis/(hepato)splenomegaly, cases with relevant antenatal findings or fetal abnormalities, and patients affected by family history, consanguinity, and endogamy. Potentially relevant niches requiring further supportive data included: early-onset cognitive decline, frontotemporal dementia, parkinsonism, and chronic inflammatory CNS disease. There was relatively weak evidence to suggest amyotrophic lateral sclerosis or progressive supranuclear gaze palsy as potential niches.

CONCLUSIONS

Several clinical niches have been identified that harbor patients at increased risk of NP-C.

Ataxia, dystonia and myoclonus in adult patients with Niemann-Pick type C

Background

Niemann-Pick type C (NP-C) is a rare autosomal recessive progressive neurodegenerative disorder caused by mutations in the NP-C 1 or 2 gene. Besides visceral symptoms, presentation in adolescent and adult onset variants is often with neurological symptoms. The most frequently reported presenting symptoms of NP-C in adulthood are psychiatric symptoms (38 %), cognitive decline (23 %) and ataxia (20 %). Myoclonus can be present, but its value in early diagnosis and the evolving clinical phenotype in NP-C is unclear. In this paper we present eight Dutch cases of NP-C of whom five with myoclonus.

Methods

Eight patients with genetically confirmed NP-C were recruited from two Dutch University Medical Centers. A structured interview and neuropsychological tests (for working and verbal memory, attention and emotion recognition) were performed. Movement disorders were assessed using a standardized video protocol. Quality of life was evaluated by questionnaires (Rand-36, SIP-68, HAQ). In four of the five patients with myoclonic jerks simultaneous EEG with EMG was performed.

Results

A movement disorder was the initial neurological symptom in six patients: three with myoclonus and three with ataxia. Two others presented with psychosis. Four experienced cognitive deficits early in the course of the disease. Patients showed cognitive deficits in all investigated domains. Five patients showed myoclonic jerks, including negative myoclonus. In all registered patients EEG-EMG coherence analysis and/or back-averaging proved a cortical origin of myoclonus. Patients with more severe movement disorders experienced significantly more physical disabilities.

Conclusions

Presenting neurological symptoms of NP-C include movement disorders, psychosis and cognitive deficits. At current neurological examination movement disorders were seen in all patients. The incidence of myoclonus in our cohort was considerably higher (63 %) than in previous publications and it was the presenting symptom in 38 %. A cortical origin of myoclonus was demonstrated. Our data suggest that myoclonus may be overlooked in patients with NP-C. All patients scored significantly lower on physical domains of HRQoL. Symptomatic treatment of movement disorders may improve physical functioning and subsequently HRQoL.

[Psychiatric disorders in adult form of Niemann-Pick disease type C]

INTRODUCTION

Niemann-Pick type C disease (NPC) is a rare genetic disease with an extremely heterogeneous clinical presentation. The adult form of this disease is usually expressed with neurological symptoms; however, non-specific psychiatric disorders are often associated. This article presents a retrospective study on a cohort of NPC patients diagnosed in France with the objectives of researching the presence of psychiatric disorders and qualifying these disorders.

METHODS

After carrying out a research within hospital records, a questionnaire was sent to patients or their relatives and their doctors.

RESULTS

The cohort was made up of 22 patients. Fifty-two questionnaires were sent to 47 different doctors. We received 67% of answers from the doctors, with 42% of positive answers. The answer rate of the families was 27%. Among the 22 patients, we found the presence of psychiatric disorders in 86% of cases. Seventy-three percent of the patients presented behavior disorders. Among them, 27% exhibited psychomotor excitation or agitation, 23% aggressiveness, 18% intolerance to frustration, 27% sleep disorders and 23% apathy, listlessness and/or clinophilia. Fifty-five percent of patients presented psychotic symptoms, with 45% with delusions and 36% with hallucinations. Seventy-seven percent of patients presented with mood disorders: 36% suffered from depression and 27% from emotional lability or mood swings. Of the 22 patients, a diagnosis of psychiatric disease was made in 50% of cases. The main diagnoses were schizophrenia (27%) and depression (23%). The other diagnoses identified were acute delirium, dysthymia, infantile psychosis, intellectual disharmonic disability and personality disorder. The average age of emergence of the troubles was 17.1 years old for neurological symptoms and 20.9 years old for psychiatric symptoms. The median age was 18 years old for neurological symptoms and 20 years old for psychiatric ones. In 45% of cases, psychiatric occurred after neurological symptoms; in 27%, they occurred before and they were concomitant in 9%. In 50% of cases, psychiatric symptoms existed before the early diagnosis of NPC; in 9%, they occurred after and in 5%, they occurred during the diagnostic process. Fifty-five percent of the patients were followed by a psychiatrist, 50% of patients had been hospitalized at least once in a psychiatric department. Fifty-five percent of the patients received neuroleptics or antipsychotics, 41% received antidepressants, 41% received mood stabilizers or anticonvulsants, 45% received anxiolytics and 23% hypnotics.

DISCUSSION

Whilst a small cohort, the low incidence of NPC (1/120,000 to 1/150,000) and the scale of a single-center study make the findings important. In our cohort, we found psychiatric disorders in most of the patients. The symptoms were varied and non-specific, and mainly found in late-onset forms of the disease. This incidence of disorder is much higher than the literature suggests, generally describing psychiatric disorders in approximately one third of NPC adult form. On the other hand, our results on schizophrenia are consistent with the updated recommendations for the diagnosis and management of NPC. According to our results, a retrospective study to develop a suspicion index to aid diagnosis of NPC suggests that psychotic symptoms are underestimated in this disease. In our cohort, we also found a significant rate of psychiatric hospitalizations and psychotropic drugs prescription that had not been previously described in the international literature. We did not have sufficient data on the effectiveness of symptomatic treatment in NPC; the literature was contradictory. It should be noted that despite the high rate of psychiatric patients in our cohort, only half of patients consulted a psychiatrist and a few of them have regular follow-up. To conclude, our study is in line with the current literature that suggests an under-estimation of psychiatric disorders in NPC, but also a likely under-diagnosis of NPC in psychiatric departments. All this data encourage us to keep alerting psychiatrists to identifying this disease in order to promote early and optimal care.

Central ocular motor disorders, including gaze palsy and nystagmus

An impairment of eye movements, or nystagmus, is seen in many diseases of the central nervous system, in particular those affecting the brainstem and cerebellum, as well as in those of the vestibular system. The key to diagnosis is a systematic clinical examination of the different types of eye movements, including: eye position, range of eye movements, smooth pursuit, saccades, gaze-holding function and optokinetic nystagmus, as well as testing for the different types of nystagmus (e.g., central fixation nystagmus or peripheral vestibular nystagmus). Depending on the time course of the signs and symptoms, eye movements often indicate a specific underlying cause (e.g., stroke or neurodegenerative or metabolic disorders). A detailed knowledge of the anatomy and physiology of eye movements enables the physician to localize the disturbance to a specific area in the brainstem (midbrain, pons or medulla) or cerebellum (in particular the flocculus). For example, isolated dysfunction of vertical eye movements is due to a midbrain lesion affecting the rostral interstitial nucleus of the medial longitudinal fascicle, with impaired vertical saccades only, the interstitial nucleus of Cajal or the posterior commissure; common causes with an acute onset are an infarction or bleeding in the upper midbrain or in patients with chronic progressive supranuclear palsy (PSP) and Niemann-Pick type C (NP-C). Isolated dysfunction of horizontal saccades is due to a pontine lesion affecting the paramedian pontine reticular formation due, for instance, to brainstem bleeding, glioma or Gaucher disease type 3; an impairment of horizontal and vertical saccades is found in later stages of PSP, NP-C and Gaucher disease type 3. Gaze-evoked nystagmus (GEN) in all directions indicates a cerebellar dysfunction and can have multiple causes such as drugs, in particular antiepileptics, chronic alcohol abuse, neurodegenerative cerebellar disorders or cerebellar ataxias; purely vertical GEN is due to a midbrain lesion, while purely horizontal GEN is due to a pontomedullary lesion. The pathognomonic clinical sign of internuclear ophthalmoplegia is an impaired adduction while testing horizontal saccades on the side of the lesion in the ipsilateral medial longitudinal fascicule. The most common pathological types of central nystagmus are downbeat nystagmus (DBN) and upbeat nystagmus (UBN). DBN is generally due to cerebellar dysfunction affecting the flocculus bilaterally (e.g., due to a neurodegenerative disease). Treatment options exist for a few disorders: miglustat for NP-C and aminopyridines for DBN and UBN. It is therefore particularly important to identify treatable cases with these conditions.

Psychiatric manifestations of treatable hereditary metabolic disorders in adults

Detecting psychiatric disorders of secondary origin is a crucial concern for the psychiatrist. But how can this reliably be done among a large number of conditions, most of which have a very low prevalence? Metabolic screening undertaken in a population of subjects with psychosis demonstrated the presence of treatable metabolic disorders in a significant number of cases. The nature of the symptoms that should alert the clinician is also a fundamental issue and is not limited to psychosis. Hereditary metabolic disorders (HMD) are a rare but important cause of psychiatric disorders in adolescents and adults, the signs of which may remain isolated for years before other more specific organic signs appear. HMDs that present purely with psychiatric symptoms are very difficult to diagnose due to low awareness of these rare diseases among psychiatrists. However, it is important to identify HMDs in order to refer patients to specialist centres for appropriate management, disease-specific treatment and possible prevention of irreversible physical and neurological complications. Genetic counselling can also be provided. This review focuses on three HMD categories: acute, treatable HMDs (urea cycle abnormalities, remethylation disorders, acute intermittent porphyria); chronic, treatable HMDs (Wilson's disease, Niemann-Pick disease type C, homocystinuria due to cystathionine beta-synthase deficiency, cerebrotendinous xanthomatosis); and chronic HMDs that are difficult to treat (lysosomal storage diseases, X-linked adrenoleukodystrophy, creatine deficiency syndrome). We also propose an algorithm for the diagnosis of HMDs in patients with psychiatric symptoms.

[Niemann-Pick type C disease and psychosis: Two siblings]

INTRODUCTION

Niemann-Pick type C disease (NPC) is a rare, neurovisceral, autosomal recessive disease, with an extremely heterogeneous clinical presentation. The adult form of the disease is usually expressed as a neurological form. Non-specific psychiatric symptoms are often associated with NPC. For some cases, it can also be expressed as an isolated psychiatric disorder form. Since 2009, the launching of a medicine called miglustat has helped to improve the disease evolution.

CASE HISTORIES

We report two siblings followed-up in the same department of psychiatry and with an atypical psychotic symptomatology. Case 1 is a 27-year-old French male. He was hospitalised several times due to disordered behaviour, psychomotor excitation, mood instability and wandering. He was originally diagnosed with schizophrenia. However, the patient's psychosis proved refractory to treatment. He also exhibited a number of neurological signs (pyramidal signs and abnormal movements of the hands, head and limbs), which were considered related to his antipsychotic medication. Three years later, a full physical, neurological and neuropsychological examination revealed various neurological and visceral symptoms. He was diagnosed with NPC based on a classical biochemical NPC-phenotype following filipin staining in cultured skin fibroblasts. NPC1 gene sequencing revealed that he was a compound heterozygote for the p.S954L and p.N1156S mutations. The patient's psychiatric and neurological symptoms are currently stabilized by miglustat, allowing the patient to cease antipsychotic medication. Case 2 is the elder sister of Case 1. She was hospitalised several times due to acute delirium, hallucinations and suicidal tendencies. She was diagnosed with paranoid schizophrenia at 22 years of age. She has received a variety of typical and atypical antipsychotics. Many of these drugs proved initially effective but the patient's symptoms repeatedly returned. The patient shows persistent and worsening gait disorder and abnormal arm movements. A follow-up neurological examination at age 29 did not detect any ataxia, cataplexy or vertical supra-nuclear gaze palsy. Direct NPC1 gene sequencing detected a mutant NPC1 allele held in common with her brother, but full sequencing of both the NPC1 and NPC2 genes and multiplex ligation-dependent probe amplification (MLPA) did not detect any other pathogenic mutation or other anomalies.

DISCUSSION

Because NPC is an autosomal recessive condition, heterozygous individuals carrying only one causal gene mutation are usually asymptomatic. Thus, while the accepted wisdom would suggest that patient 2 is not affected by the disease, it is interesting to consider why she has developed neurological and psychiatric disorders like her brother. Several hypotheses are discussed: mental expression in heterozygous genetic factor predisposing to schizophrenia, comorbidity or fortuitous association. It is not currently known whether a patient with a single NPC gene mutation can express NPC in full, partially, or perhaps just to a minimal degree. This case of a patient with a heterozygous "carrier" NPC genotype and neuropsychiatric disorders suggestive of the disease raises the possibility that symptomatic heterozygous NPC patients may exist. On the other hand, if the heterozygous genotype of patient 2 does not give rise to symptomatic disease, it is pertinent to question whether it could be a predisposing factor for the development of psychiatric pathologies. There are currently no published data on the occurrence of heterozygous NPC1 or NPC2 mutations among patients with atypical psychiatric presentations combined with neurological symptoms. Conversely, there are no published data demonstrating an increased frequency of psychiatric disorders in families affected by NPC. Finally, in view of the history of psychiatric disorders in this family, it is possible that psychosis simply occurred concomitantly with symptomatic NPC in patient 1 by chance, and that schizophrenia occurred simultaneously with an asymptomatic NPC carrier genotype in patient 2. To investigate this further, NPC patients' carrier family members (parents and siblings) should be fully screened for signs suggestive of the disease.

Diagnostic and treatment implications of psychosis secondary to treatable metabolic disorders in adults: a systematic review

Objective

It is important for psychiatrists to be aware of certain inborn errors of metabolism (IEMs) as these rare disorders can present as psychosis, and because definitive treatments may be available for treating the underlying metabolic cause. A systematic review was conducted to examine IEMs that often present with schizophrenia-like symptoms.

Data sources

Published literature on MEDLINE was assessed regarding diseases of homocysteine metabolism (DHM; cystathionine beta-synthase deficiency [CbS-D] and homocysteinemia due to methyltetrahydrofolate reductase deficiency [MTHFR-D]), urea cycle disorders (UCD), acute porphyria (POR), Wilson disease (WD), cerebrotendinous-xanthomatosis (CTX) and Niemann-Pick disease type C (NP-C).

Study selection

Case reports, case series or reviews with original data regarding psychiatric manifestations and cognitive impairment published between January 1967 and June 2012 were included based on a standardized four-step selection process.

Data extraction

All selected articles were evaluated for descriptions of psychiatric signs (type, severity, natural history and treatment) in addition to key disease features.

Results

A total of 611 records were identified. Information from CbS-D (n = 2), MTHFR-D (n = 3), UCD (n = 8), POR (n = 12), WD (n = 11), CTX (n = 14) and NP-C publications (n = 9) were evaluated. Six non-systematic literature review publications were also included. In general, published reports did not provide explicit descriptions of psychiatric symptoms. The literature search findings are presented with a didactic perspective, showing key features for each disease and psychiatric signs that should trigger psychiatrists to suspect that psychotic symptoms may be secondary to an IEM.

Conclusion

IEMs with a psychiatric presentation and a lack of, or sub-clinical, neurological signs are rare, but should be considered in patients with atypical psychiatric symptoms.

Complete recovery from psychosis upon miglustat treatment in a juvenile Niemann-Pick C patient

Niemann-Pick disease type C is a rare lipid trafficking disorder characterized by the accumulation of cholesterol and glycosphingolipids in the brain and viscera. Perinatal, early infantile, late infantile, juvenile and adult forms are distinguished based on the age of manifestation. In the juvenile form, patients in their early years are usually, but not always, symptom free, but present with neurodegeneration later in their lives. These include clumsiness, ataxia, seizures, motor and intellectual decline. Psychiatric manifestations may occur at any stage of the disease. These manifestations include schizophrenia, presenile dementia, depression or psychosis. In 2009, miglustat was approved for the therapy of the disease. We present a case of a patient with juvenile Niemann-Pick C disease whose psychosis was reversed completely by miglustat treatment. Based on our clinical experience we suggest considering Niemann-Pick C in cases of therapy-resistant psychosis and encourage the introduction of miglustat in Niemann-Pick C patients even in the most advanced cases, with respect to psychiatric illness.

Treatable inborn errors of metabolism causing neurological symptoms in adults

BACKGROUND

The identification of inborn errors of metabolism (IEM) in adults presenting with a wide range of neurological symptoms is a relatively new field in medicine. We sought to identify which treatable IEM have been diagnosed for the first time in adults and generate a protocol for metabolic screening targeting those treatable disorders.

METHODS

Medline/Pubmed searches of English language literature limited to the adult age group were performed. Diseases identified through this search were then compared to previously published lists of treatable IEM in both adults and children.

RESULTS

85% of the treatable conditions known to cause global developmental delay or intellectual disability in children had reports where the diagnosis of that IEM was made in one or more adult patients with neurological symptoms. Screening tests in blood, urine, CSF and MRI can detect most of these treatable conditions but the diagnostic accuracy of these screening tests in adults is not clear.

CONCLUSION

Treatable IEM need to be considered in the differential diagnosis of neurological symptoms in patients of any age.

Treatment of Niemann--pick type C disease by histone deacetylase inhibitors

Niemann-Pick type C disease (NPC) is a devastating, recessive, inherited disorder that causes accumulation of cholesterol and other lipids in late endosomes and lysosomes. Mutations in 2 genes, NPC1 and NPC2, are responsible for the disease, which affects about 1 in 120,000 live births. About 95% of patients have mutations in NPC1, a large polytopic membrane protein that is normally found in late endosomes. More than 200 missense mutations in NPC1 have been found in NPC patients. The disease is progressive, typically leading to death before the age of 20 years, although some affected individuals live well into adulthood. The disease affects peripheral organs, including the liver, spleen, and lungs, but the most severe symptoms are associated with neurological disease. There are some palliative treatments that slow progression of NPC disease. Recently, it was found that histone deacetylase (HDAC) inhibitors that are effective against HDACs 1, 2, and 3 can reduce the cholesterol accumulation in fibroblasts derived from NPC patients with mutations in NPC1. One example is vorinostat. As vorinostat is a Food and Drug Administration-approved drug for treatment of cutaneous T-cell lymphoma, this opens up the possibility that HDAC inhibitors could be repurposed for treatment of this rare disease. The mechanism of action of the HDAC inhibitors requires further study, but these drugs increase the level of the NPC1 protein. This may be due to post-translational stabilization of the NPC1 protein, allowing it to be transported out of the endoplasmic reticulum.

Psychiatric manifestations in cerebrotendinous xanthomatosis

Cerebrotendinous xanthomatosis (CTX) is a rare and severe, but treatable, inborn disorder of bile acid biosynthesis and sterol storage with autosomal recessive inheritance and variable clinical presentation. CTX treatment consists of chenodeoxycholic acid and must be started as early as possible to prevent permanent disability. Psychiatric manifestations are rare and non-specific, and often lead to significant diagnostic and treatment delay. Therefore, better recognition of the gamut of psychiatric manifestations in CTX can diminish the risk of misdiagnosis and irreversible neurological deterioration. We hereby describe the psychiatric features in CTX. A complete review of all published cases of CTX in the medical literature was undertaken and the case reports with psychiatric presentation were collected and analyzed. We also describe the psychiatric features in relation to the neurological semeiology in six patients with CTX diagnosed at the La Salpêtrière Hospital. We conclude that psychiatric manifestations in CTX follow a bimodal/bitemporal pattern, appearing early in the disease course in the form of a behavioral/personality disorder associated with learning difficulties or mental retardation, or manifesting in advanced disease in the setting of dementia as rich neuropsychiatric syndromes, such as frontal, orbitofrontal or frontotemporal syndromes of cortico-subcortical dementia encompassing behavioral/personality disturbance, affective/mood disorders or psychotic disorders. Behavioral/personality disturbance in childhood or adolescence, especially when accompanied by learning difficulties, should therefore lead to further investigation to exclude CTX, as early diagnosis and treatment is critical for prognosis.