Identification of a KDM6A somatic mutation responsible for Kabuki syndrome by excluding a conflicting KMT2D germline variant through episignature analysis.

Kabuki syndrome (KS) is a congenital disorder caused by mutations in either KMT2D on chromosome 12 or KDM6A on chromosome X, encoding a lysine methyltransferase and a lysine demethylase, respectively. A 9-year-4-month-old male patient with a normal karyotype presented with KS and autism spectrum disorder. Genetic testing for KS was conducted by Sanger sequencing and episignature analysis using DNA methylation array data. The patient had a mosaic stop-gain variant in KDM6A and a heterozygous missense variant (rs201078160) in KMT2D. The KDM6A variant is expected to be deleterious. The KMT2D variant pathogenicity has been inconsistently reported in the ClinVar database. Using biobanking resources, we identified two heterozygous individuals possessing the rs201078160 variant. In a subsequent episignature analysis, the KS patient showed the KS episignature, but two control individuals with the rs201078160 variant did not. Our results indicate that the mosaic stop-gained variant in KDM6A, but not the rs201078160 variant in KMT2D, is responsible for the KS phenotype in the patient. This study further demonstrated the utility of DNA methylation information in diagnosing rare genetic diseases and emphasized the importance of a reference dataset containing both genotype and DNA methylation information.

Osteoporosis pathology in people with severe motor and intellectual disability.

OBJECTIVES: We assessed the severity and pathology of osteoporosis in children and adults with severe motor and intellectual disabilities (SMID) by evaluating bone enzymes, by which we aimed to determine adequate treatment approaches for preventing fractures. METHODS: Ninety patients (44 men, 46 women; mean age, 34.5 years) underwent bone quality assessment. Quantitative ultrasonography (QUS) was used to measure the T-score and Z-score of the calcaneus, and blood tests were used to measure bone-specific alkaline phosphatase and tartrate-resistant acid phosphatase 5b levels as bone formation and resorption markers, as well as calcium, phosphorous, and parathyroid hormone levels as routine examination. RESULTS: Bone formation and resorption marker levels were within normal ranges in adults, although they were high during the growth period in children and adolescents and in elderly women. Patients receiving tube feeding showed a significantly lower Z-score than those without tube feeding. Tube feeding was a significant factor for the Z-score, whereas age, vitamin supplements, and anti-epileptic drugs were not. CONCLUSIONS: The severity of osteoporosis in SMID started during the growth period and seems to be caused by a lack of an effective increase in bone mineral density. Any treatment should be started during the growth period. More study about tube feeding is needed.

Elimination of amyloid precursor protein in senile plaques in the brain of a patient with Alzheimer-type dementia and Down syndrome.

The average lifespan of individuals with Down syndrome has approximately doubled over the past three decades to 55-60 years. To reveal the pathogenic process of Alzheimer-type dementia in individuals with Down syndrome, we immunohistochemically examined senile plaque formation in the cerebral cortex in the autopsy brain and compared findings with our previous studies. We described a 52-year-old female with Down syndrome who developed progressively more frequent myoclonus following cognitive decline and died at the age of 59 years. Her karyotype [46XX, inv(9)(p12q13), i(21)(q10)] included triplication of the gene for amyloid precursor protein and the Down syndrome critical region. On microscopy, very few gamma-aminobutyric acid-ergic (GABAergic) neurons, in the form of small granular cells, in the cortex and Purkinje cells in the cerebellum were visible. In our previous study, amyloid precursor protein immunoreactivity was first noted in senile plaques at the age of 32 years. In this patient, even though amyloid ß immunoreactivity was detected in the cores of senile plaques and diffuse plaques, amyloid precursor protein immunoreactivity was not noted in senile plaques in the frontal cortex. Amyloid precursor protein and its derivative amyloid-ß play an important role in the formation of senile plaques and the time course of immunoreactive expression may be related to the pathogenic process of Alzheimer-type dementia.

Arima syndrome caused by CEP290 specific variant and accompanied with pathological cilium; clinical comparison with Joubert syndrome and its related diseases.

OBJECTIVE: Arima syndrome (AS) is a rare disease and its clinical features mimic those of Joubert syndrome or Joubert syndrome-related diseases (JSRD). Recently, we clarified the AS diagnostic criteria and its severe phenotype. However, genetic evidence of AS remains unknown. We explored causative genes of AS and compared the clinical and genetic features of AS with the other JSRD. PATIENTS AND METHODS: We performed genetic analyses of 4 AS patients of 3 families with combination of whole-exome sequencing and Sanger sequencing. Furthermore, we studied cell biology with the cultured fibroblasts of 3 AS patients. RESULTS: All patients had a specific homozygous variant (c.6012-12T>A, p.Arg2004Serfs*7) or compound heterozygous variants (c.1711+1G>A; c.6012-12T>A, p.Gly570Aspfs*19;Arg2004Serfs*7) in centrosomal protein 290 kDa (CEP290) gene. These unique variants lead to abnormal splicing and premature termination. Morphological analysis of cultured fibroblasts from AS patients revealed a marked decrease of the CEP290-positive cell number with significantly longer cilium and naked and protruded ciliary axoneme without ciliary membrane into the cytoplasm. CONCLUSION: AS resulted in cilia dysfunction from centrosome disruption. The unique variant of CEP290 could be strongly linked to AS pathology. Here, we provided AS specific genetic evidence, which steers the structure and functions of centrosome that is responsible for normal ciliogenesis. This is the first report that has demonstrated the molecular basis of Arima syndrome.

[A case of prolonged paroxysmal sympathetic hyperactivity].

We report the case of a 4-year-old girl who presented with paroxysmal sympathetic hyperactivity (PSH), after developing severe hypoxic-ischemic-encephalopathy because of cardiopulmonary arrest. She showed dramatic paroxysmal sympathetic activity with dystonia. She was treated with wide variety of medications against PSH, which were found to be effective in previous studies. Among them, morphine, bromocriptine, propranolol, and clonidine were effective in reducing the frequency of her attacks while gabapentin, baclofen, dantrolene, and benzodiazepine were ineffective. Though the paroxysms decreased markedly after the treatment, they could not be completely controlled beyond 500 days. Following the treatment, levels of plasma catecholamines and their urinary metabolites decreased to normal during inter- paroxysms. However, once a paroxysm had recurred, these levels were again very high. This case study is considered significant for two rea- sons. One is that PSH among children have been rarely reported, and the other is that this case of prolonged PSH delineated the transition of plasma catecholamines during the treatment. The excitatory: inhibitory ratio (EIR) model proposed by Baguley was considered while dis- cussing drug sensitivity in this case. Accumulation of similar case studies will help establish more effective treatment strategies and elucidate the pathophysiology of PSH.

Nationwide survey of Arima syndrome: revised diagnostic criteria from epidemiological analysis.

AIM: We have never known any epidemiological study of Arima syndrome since it was first described in 1971. To investigate the number of Arima syndrome patients and clarify the clinical differences between Arima syndrome and Joubert syndrome, we performed the first nationwide survey of Arima syndrome, and herein report its results. Furthermore, we revised the diagnostic criteria for Arima syndrome. METHODS: As a primary survey, we sent out self-administered questionnaires to most of the Japanese hospitals with a pediatric clinic, and facilities for persons with severe motor and intellectual disabilities, inquiring as to the number of patients having symptoms of Arima syndrome, including severe psychomotor delay, agenesis or hypoplasia of cerebellar vermis, renal dysfunction, visual dysfunction and with or without ptosis-like appearance. Next, as the second survey, we sent out detailed clinical questionnaires to the institutes having patients with two or more typical symptoms. RESULTS: The response rate of the primary survey was 72.7% of hospitals with pediatric clinic, 63.5% of national hospitals and 66.7% of municipal and private facilities. The number of patients with 5 typical symptoms was 13 and that with 2-4 symptoms was 32. The response rate of the secondary survey was 52% (23 patients). After reviewing clinical features of 23 patients, we identified 7 Arima syndrome patients and 16 Joubert syndrome patients. Progressive renal dysfunction was noticed in all Arima syndrome patients, but in 33% of those with Joubert syndrome. CONCLUSION: It is sometimes difficult to distinguish Arima syndrome from Joubert syndrome. Some clinicians described a patient with Joubert syndrome and its complications of visual dysfunction and renal dysfunction, whose current diagnosis was Arima syndrome. Thus, the diagnosis of the two syndromes may be confused. Here, we revised the diagnostic criteria for Arima syndrome.

[Efficacy of botulinum toxin type A against cervical dystonia and muscular hypertonia in persons with severe motor and intellectual disabilities with respiratory problems and/or dysphagia].

We administered intramuscular injections of botulinum toxin type A (BTX-A) in 11 persons with cervical dystonia (CD) and muscular hypertonia (MH). All patients had severe motor and intellectual disabilities (SMID). Furthermore, in 10 patients, SMID was accompanied by respiratory problems and/or dysphagia. Three patients received night nasal intermittent positive pressure ventilation and 3 had undergone tracheotomy; 5 patients had upper respiratory problems. Because of these complications, BTX-A dose was gradually increased in those patients until the desired effect was obtained (mean last dose, 6.8 u/kg/dose). All patients were clinically assessed with the Tsui scale before treatment with BTX-A. At 1, 2, 4, and 8 weeks after BTX-A injections, responses to the injections were assessed with the Tsui scale repetitively in all patients. Significant or mild improvements in the Tsui scale scores were observed in 8 patients without any severe adverse effects. In addition, some improvements in respiration and body weight gain were observed. We observed a reduction in the number of oral medications in 10 cases. Administration of BTX-A for the treatment of SMID has numerous benefits, not all of which can be explained by Tsui scale scores. BTX-A is safe and has potential for use in the treatment of CD and MH with respiratory problems and/or dysphagia.

[Three cases of benign myoclonus of early infancy].

Benign myoclonus of early infancy (BMEI) is a non-epileptic paroxysmal phenomenon. Some patients with BMEI were mistakenly treated as infantile spasms, because the fits resemble to tonic spasms in infantile spasms and they occur in cluster. However, the patients have normal development and no abnormal electroencephalograms (EEG), and the fits spontaneously subside without sequelae. There are only a few reports on BMEI, and it is not widely recognized in Japan. We report three cases of BMEI. All the cases were suspected to have infantile spasms from the characteristic features of paroxysmal events, and the parents had strong anxiety because of recurrent fits. However, the fits decreased dramatically in about three months, and spontaneously disappeared within one year without any sequelae. BMEI might be included in cases of suspected infantile spasms, and such patients should be followed by monthly EEG examinations and close observation for other seizure phenomena. To avoid unnecessary treatments, such patients should be observed without any therapeutic trials including antiepileptic drugs.