A new biomarker candidate for spinal muscular atrophy: Identification of a peripheral blood cell population capable of monitoring the level of survival motor neuron protein.

Spinal muscular atrophy (SMA) is a severe genetic neuromuscular disorder caused by insufficiency of functional survival motor neuron (SMN) protein. Several clinical trials have been conducted with the aim of upregulating the expression of the SMN protein in SMA patients. In order to evaluate the efficiency of these SMN-targeted approaches, it has become necessary to verify SMN protein levels in the cells of SMA patients. Accordingly, we have developed a method allowing the evaluation of the functional SMN protein with < 1.5 mL of peripheral blood using imaging flow cytometry. The expression of SMN protein in CD3+, CD19+, and CD33++ cells obtained from SMA patients, was significantly reduced compared with that in cells from control subjects. In spot analysis of CD33++ cells, the intensities of SMN spots were significantly reduced in SMA subjects, when compared with that in controls. Therefore, SMN spots implied the presence of functional SMN protein in the cell nucleus. To our knowledge, our results are the first to demonstrate the presence of functional SMN protein in freshly isolated peripheral blood cells. We anticipate that SMN spot analysis will become the primary endpoint assay for the evaluation and monitoring of therapeutic intervention, with SMN serving as a reliable biomarker of therapeutic efficacy in SMA patients.

Relationships between long-term observations of motor milestones and genotype analysis results in childhood-onset Japanese spinal muscular atrophy patients.

AIM: To clarify the long-term natural history of SMA in Japanese patients by investigating the peak motor milestones of cases 7months through 57years of age, in efforts to contribute to evaluating outcomes of new therapeutic interventions. METHODS: We sub-classified 112 SMA type I-III cases into type Ia, type Ib, type IIa, type IIb, type IIIa and type IIIb, according to peak motor milestone achieved, and analyzed the SMN1, SMN2 and NAIP genes in relation to clinical subtypes. RESULTS: In type I cases, there was a significant difference (p<0.0001), depending on whether or not head control was obtained, in the time of ventilation support being required. In type II cases as well, the time at which the ability to maintain the sitting position independently was lost also differed significantly (p<0.01) between those acquiring the ability to sit unaided within eight months after birth and those acquiring this ability after eight months of age. In type III cases, being able versus unable to climb stairs was associated with a significant difference (p=0.02) in the median time until loss of walking independently. Positive correlations were also seen between copy numbers and the clinical severity of SMA. CONCLUSION: Our long-term results show peak motor milestone evaluations distinguishing between subtypes to be useful not only as outcome measures for assessing treatment efficacy in clinical trials but also for predicting the clinical courses of Japanese SMA patients.

Gender Effects on the Clinical Phenotype in Japanese Patients with Spinal Muscular Atrophy.

BACKGROUND: Spinal muscular atrophy (SMA) is a neuromuscular disease caused by a mutation in SMN1. SMA is classified into three subtypes (types 1, 2, 3) based on achieved motor milestones. Although NAIP and SMN2 are widely accepted as SMA-modifying factors, gender-related modifying factors or gender effects on the clinical phenotype are still controversial. METHODS: A total of 122 Japanese patients with SMA, of which SMN1 was homozygously deleted, were analyzed from the perspective of the achieved motor milestone, NAIP status and SMN2 copy number. RESULTS: A predominance of male patients was observed in SMA type 3 (the walker group) without NAIP-deletion or with high SMN2 copy number (3 or 4 copies). CONCLUSION: We suggest the presence of gender-related modifiers on disease severity in SMA patients. The modifiers may contribute only in the presence of NAIP and a high copy number of SMN2.

Imaging Flow Cytometry Analysis to Identify Differences of Survival Motor Neuron Protein Expression in Patients With Spinal Muscular Atrophy.

BACKGROUND: Spinal muscular atrophy is a neurodegenerative disorder caused by the deficient expression of survival motor neuron protein in motor neurons. A major goal of disease-modifying therapy is to increase survival motor neuron expression. Changes in survival motor neuron protein expression can be monitored via peripheral blood cells in patients; therefore we tested the sensitivity and utility of imaging flow cytometry for this purpose. METHODS: After the immortalization of peripheral blood lymphocytes from a human healthy control subject and two patients with spinal muscular atrophy type 1 with two and three copies of SMN2 gene, respectively, we used imaging flow cytometry analysis to identify significant differences in survival motor neuron expression. A bright detail intensity analysis was used to investigate differences in the cellular localization of survival motor neuron protein. RESULTS: Survival motor neuron expression was significantly decreased in cells derived from patients with spinal muscular atrophy relative to those derived from a healthy control subject. Moreover, survival motor neuron expression correlated with the clinical severity of spinal muscular atrophy according to SMN2 copy number. The cellular accumulation of survival motor neuron protein was also significantly decreased in cells derived from patients with spinal muscular atrophy relative to those derived from a healthy control subject. CONCLUSIONS: The benefits of imaging flow cytometry for peripheral blood analysis include its capacities for analyzing heterogeneous cell populations; visualizing cell morphology; and evaluating the accumulation, localization, and expression of a target protein. Imaging flow cytometry analysis should be implemented in future studies to optimize its application as a tool for spinal muscular atrophy clinical trials.

Two Japanese patients with Leigh syndrome caused by novel SURF1 mutations.

We report two patients with Leigh syndrome that showed a combination of facial dysmorphism and MRI imaging indicating an SURF1 deficiency, which was confirmed by sequence analysis. Case 1 is a 3-year-old girl with failure to thrive and developmental delay. She presented with tachypnea at rest and displayed facial dysmorphism including frontal bossing, lateral displacement of inner canthi, esotropia, maxillary hypoplasia, slightly upturned nostril, and hypertrichosis dominant on the forehead and extremities. Case 2 is an 8-year-old boy with respiratory failure. He had been diagnosed as selective complex IV deficiency. Case 2 displayed facial dysmorphism and hypertrichosis. Since both patients displayed characteristic facial dysmorphism and MRI findings, we sequenced the SURF1 gene and identified two heterozygous mutations; c.49+1 G>T and c.752_753del in Case 1, and homozygous c.743 C>A in Case 2. For patients with Leigh syndrome showing these facial dysmorphism and hypertrichosis, sequence analysis of the SURF1 gene may be useful.

Brain MRI findings of older patients with Pallister-Killian syndrome.

Pallister-Killian syndrome (PKS) is a disorder caused by a mosaic tetrasomy of chromosome 12p, which manifests with dysmorphism, intellectual disabilities, auditory disturbance, and epilepsy. Here, we describe the findings of brain magnetic resonance (MR) imaging in two patients with PKS. One patient, a 43-year-old man, showed multiple lesions with high signal intensity on T2-weighted image (WI) in the basal ganglia, and widespread T2 elongation in the periventricular white matter. The same signal change was also present in the pontine base. The other patient, a 37-year-old woman, showed T2-high lesions in the bilateral putamina and the parietal periventricular white matter. There was prominent atrophy of the cerebellum and brainstem in this latter case. Both cases showed cortical atrophy with frontal predominance, with accompanying dilatation of the lateral ventricles. Hypoplastic corpus callosum was also present in both cases. Cerebral atrophy with ventricular dilatation has been often described in PKS cases, but many of the MR findings in the present patients have never been reported. Such findings may appear with advancing age in PKS. Since 12p mosaicism is rarely detected in peripheral blood lymphocytes, examination of buccal mucosal cells with fluorescent in situ hybridization method is preferable for the diagnosis of PKS. Recognition of the characteristic features on cranial MR imaging, in addition to the characteristic facial appearance in adulthood, should prompt the correct diagnosis of adult PKS patients.

[Disturbed respiratory cycle accompanying hypoxic-ischemic encephalopathy].

We report the case of a 2-year-old boy who experienced total asphyxia at 4 months of age, and suffered abnormalities at specific phases of the respiratory cycle. The patient was bedridden due to severe tetraplegia and showed little response to external stimuli. He has been tube-fed since the initial asphyxia and a tracheotomy was performed after recurrent hypoxic episodes as a result of the respiratory dysfunction. Upon examination, his respiratory pattern was characterized by arrest during the inspiratory phase with a possible over-riding secondary inspiration. The respiratory pause at the inspiratory phase was markedly prolonged during an episode of pulmonary infection, resulting in recurrent cyanosis that necessitated artificial ventilation. The "second" inspiration typically occurred during the mid- or late-inspiratory phases, with this pattern often shown to be variable after epileptic seizures. The characteristic breathing of this patient suggested that difficulty in forming a normal respiratory cycle, other than during periods of hypoventilation or apnoea, could be a significant respiratory dysfunction following asphyxiation. Strategies for the management of such patients should be carefully designed after close observation of breathing patterns within the respiratory cycle, and with consideration for the influence of epileptic seizures and other inputs from somatic afferents.

Cerebellopontine calcification: a new entity of idiopathic intracranial calcification?

We report the autopsy case of a 40-year-old woman with severe intellectual and motor disabilities, who showed calcification in the cerebellum and pons but not in the basal ganglia on CT scan, and died of intracranial hemorrhage due to intractable hypertension. At autopsy, numerous calcium deposits were noted in the cerebellar cortex, the dentate nucleus, the cerebellar white matter and the ventral pons. These deposits were distributed both in the neuropil and the white matter, but rarely within the arterial walls or in contact with capillaries. This weak relationship between calcification and the blood vessels, in addition to the paucity of basal ganglia calcification, is in contrast to the findings with other disorders involving intracranial calcification, including Fahr's disease and calcium metabolism disorders. Immunohistochemistry revealed intense staining of calbindin-D28K and parvalbumin at sites of calcium deposits both in the present case and in a case of pseudohypoparathyroidism, whereas these proteins were not localized to calcium deposits in the cerebellum of a Fahr's disease brain. We propose that the present case may represent a distinct entity among diseases characterized by idiopathic intracranial calcification. In addition, calcium-binding proteins may be involved in the calcification process in some cases with intracranial calcification.

Laryngeal dystonia in xeroderma pigmentosum.

We report on three patients with xeroderma pigmentosum group A (XPA) who showed laryngeal stridor in their 20s. The stridor appeared on feeding and emotional excitation, was exaggerated during respiratory infection and was life-threatening on some occasions. Adduction of the vocal cords during inspiration, observed by laryngoscopy, confirmed laryngeal dystonia in all cases. This type of focal dystonia may be characteristic in XPA and requires special attention during the management of these patients to avoid serious complications.

A magnetoencephalographic study of astatic seizure in myoclonic astatic epilepsy.

To study the pathophysiologic mechanism of astatic seizures in a patient with myoclonic astatic epilepsy of early childhood, ictal magnetoencephalography was recorded and the neuronal pathway involved was analyzed. The patient was a 12-year-old female who developed myoclonic and astatic seizures including nodding and sudden falling at the age of 4. The current source of spikes during nodding attacks was located in the bilateral frontal area with left predominance, possibly in the premotor cortex. Although we could not claim, on the basis of our findings, that myoclonic astatic epilepsy of early childhood is a type of focal epilepsy, it seems likely that the premotor cortex might be more excitable than other areas. Thus we speculate that the functionally altered premotor-reticulospinal tract which normally controls postural adjustment might play an important role in the generation of myoclonic astatic seizures. Furthermore, the underlying mechanism in the brainstem seems to be common, at least in part, for infantile spasms when considering the efficacy of synthetic adrenocorticotropic hormone for nodding seizures.

[A case of Friedreich's ataxia having no abnormal gene].

We report here a 25-year-old girl with Friedreich's ataxia (FA) who showed slowly progressive ataxia, deep sensory disturbance and loss of large myelinated fiber in the sural nerve. There was no evidence of cerebellar atrophy or abnormal values of vitamin E, albumin, CK, and gamma-globulin in the serum. Except for mild mental retardation, her clinical and laboratory findings were consistent with those of FA. However, she had no abnormal GAA trinucleotide repeat expansion on chromosome 9q13, unlike typical FA patients in Europe. Her cardiac muscle is not involved instead of 20 years have passed since her ataxia developed. She is considered to belong to a specific type of FA which lacks cardiac muscle involvement and abnormal gene encoding frataxin.