The Marinesco-Sjögren syndrome examined by computed tomography, magnetic resonance, and 18F-2-fluoro-2-deoxy-D-glucose and positron emission tomography

Role of the HSP70 Co-Chaperone SIL1 in Health and Disease

Cell surface and secreted proteins provide essential functions for multicellular life. They enter the endoplasmic reticulum (ER) lumen co-translationally, where they mature and fold into their complex three-dimensional structures. The ER is populated with a host of molecular chaperones, associated co-factors, and enzymes that assist and stabilize folded states. Together, they ensure that nascent proteins mature properly or, if this process fails, target them for degradation. BiP, the ER HSP70 chaperone, interacts with unfolded client proteins in a nucleotide-dependent manner, which is tightly regulated by eight DnaJ-type proteins and two nucleotide exchange factors (NEFs), SIL1 and GRP170. Loss of SIL1′s function is the leading cause of Marinesco-Sjögren syndrome (MSS), an autosomal recessive, multisystem disorder. The development of animal models has provided insights into SIL1′s functions and MSS-associated pathologies. This review provides an in-depth update on the current understanding of the molecular mechanisms underlying SIL1′s NEF activity and its role in maintaining ER homeostasis and normal physiology. A precise understanding of the underlying molecular mechanisms associated with the loss of SIL1 may allow for the development of new pharmacological approaches to treat MSS.

George Marinesco in the Constellation of Modern Neuroscience

George Marinesco is the founder of Romanian School of Neurology and one of the most remarkable neuroscientists of the last century. He was the pupil of Jean-Martin Charcot in Salpêtrière Hospital in Paris, France, but visited many other neurological centers where he met the entire constellation of neurologists of his time, including Camillo Golgi and Santiago Ramón y Cajal. The last made the preface of Nervous Cell, written in French by Marinesco. The original title was “La Cellule Nerveuse” and is considered even now a basic reference book for specialists in the field. He was a refined clinical observer with an integrative approach, as could be seen from the multitude of his discoveries. The descriptions of the succulent hand in syringomyelia, senile plaque in old subjects, palmar jaw reflex known as Marinesco-Radovici sign, or the application of cinematography in medicine are some of his important contributions. He was the first who described changes of locus niger in a patient affected by tuberculosis, as a possible cause in Parkinson disease. Before modern genetics, Marinesco and Sjögren described a rare and complex syndrome bearing their names. He was a hardworking man, focused on his scientific research, did not accepted flattering of others and was a great fighter against the injustice of the time.

Heterogeneity of Marinesco-Sjögren syndrome: report of two cases

Marinesco-Sjögren syndrome is an autosomal recessive, multiorgan disorder with cardinal features of cerebellar ataxia, congenital or early childhood cataracts, psychomotor retardation, myopathy, and short stature. Mutations in the SIL1 gene on chromosome 5q31 were demonstrated to cause Marinesco-Sjögren syndrome. We describe two Turkish patients with clinical characteristics of Marinesco-Sjögren syndrome, but without mutations in SIL1. These two patients also manifested cerebral white matter involvement in cranial imaging, which was previously described in Marinesco-Sjögren syndrome. Marinesco-Sjögren syndrome is genetically heterogeneous, and mutations of SIL1 are often not evident. Consequently, we presume that new genes for Marinesco-Sjögren syndrome await discovery. New genes hold the promise of furthering the mechanistic understanding of the condition, enabling clinically meaningful genetic classification schemes to be designed.

Marinesco-Sjögren syndrome in a male with mild dysmorphism

Marinesco-Sjogren syndrome (MSS) is a rare, autosomal recessive disorder comprising cataracts, cerebellar ataxia caused by cerebellar hypoplasia, mild to moderate mental retardation, neuromuscular weakness, short stature, hypergonadotrophic hypogonadism, and skeletal anomalies. The syndrome was recently mapped to chromosome 5q31, but there is evidence for genetic heterogeneity, and no gene has been identified. We report a 5-year-old male with cataracts, ataxia, a progressive cerebellar atrophy, developmental delay, seizures, hypotonia, and a sensorimotor neuropathy consistent with many cases of MSS. He also had mild craniofacial dysmorphism consisting of hypertrichosis and synophrys, deep-set eyes with epicanthic folds, a flat philtrum, a high palate, short thumbs, and a wide sandal gap between the first and second toes. Skeletal findings included an increased kyphosis. We reviewed the literature on MSS to determine if craniofacial dysmorphism and the presence of neuropathy and/or myopathy would prove to be diagnostically useful in this phenotypically heterogeneous condition. The majority of cases of MSS do not have craniofacial dysmorphism, but other cases have been reported with features such as ptosis or a myopathic facies that are likely to reflect the underlying myopathic or neuromuscular processes in MSS.

Homozygosity mapping of Marinesco-Sjögren syndrome to 5q31

Marinesco-Sjögren syndrome (MSS), first described in 1931, is an autosomal recessive condition characterised by somatic and mental retardation, congenital cataracts and cerebellar ataxia. Progressive myopathy was later reported to be also a cardinal sign of MSS, with myopathic changes on muscle biopsies. Hypergonadotrophic hypogonadism and skeletal deformities related to pronounced hypotonia were also reported. The major differential diagnosis of MSS is the syndrome defined by congenital cataracts, facial dysmorphism and peripheral neuropathy (CCFDN), which is localised to 18qter. Using homozygosity mapping strategy in two large consanguineous families of Turkish and Norwegian origin, respectively, we have identified the MSS locus on chromosome 5q31. LOD score calculation, including the consanguinity loops, gave a maximum value of 2.9 and 5.6 at theta=0 for the Turkish and the Norwegian families, respectively, indicating linkage between the disease and the D5S1995-D5S436 haplotype spanning a 9.3 cM interval. Patients of the two families presented with the strict clinical features of MSS. On the other hand, the study of two smaller French and Italian families, initially diagnosed as presenting an atypical MS syndrome, clearly excluded linkage from both the MSS locus on 5q31 and the CCFDN locus in 18qter. Patients of the two excluded families had all MSS features (but the myopathic changes) plus peripheral neuropathy and optic atrophy, and various combinations of microcornea, hearing impairment, seizures, Type I diabetes, cerebral atrophy and leucoencephalopathy, indicating that only the pure MSS syndrome is a homogeneous genetic entity.

Genetic identity of Marinesco-Sjögren/myoglobinuria and CCFDN syndromes

OBJECTIVE AND BACKGROUND

To describe three Gypsy families with Marinesco-Sjögren syndrome (MSS), demyelinating neuropathy, and recurrent episodes of myoglobinuria in five of the six affected subjects. Because these families originated from the same genetically isolated founder population as did patients with congenital cataracts facial dysmorphism neuropathy (CCFDN) syndrome, and because the two syndromes have clinical manifestations in common, we hypothesized that the two related, albeit distinct, syndromes may represent clinical variants of a single genetic disorder.

METHODS

Clinical studies were conducted and linkage and haplotype analyses were performed for the three families. A total of 16 individuals, including the 6 with MSS and 10 unaffected relatives, were genotyped for six polymorphic microsatellite markers from the CCFDN region on 18qter.

RESULTS

Linkage analysis of markers in the 18qter region, where we previously had located the CCFDN gene, produced a lod score of 3.55, demonstrating colocalization of the gene responsible for MSS with demyelinating neuropathy and myoglobinuria with the CCFDN gene. Moreover, the patients with MSS shared the conserved marker haplotype found in CCFDN chromosomes.

CONCLUSIONS

These data suggest that Marinesco-Sjögren syndrome with peripheral neuropathy and myoglobinuria, and congenital cataracts facial dysmorphism neuropathy syndrome are genetically identical and are caused by a single founder mutation.

Hereditary ataxias

There are many causes of hereditary ataxia. These can be grouped into categories of autosomal recessive, autosomal dominant, and X-linked. Molecularly, many of them are due to trinucleotide repeat expansions. In Friedreich ataxia, the trinucleotide repeat expansions lead to a "loss of function." In the dominant ataxias, the expanded repeats lead to a "gain of function," most likely through accumulation of intranuclear (and less commonly cytoplasmic) polyglutamine inclusions. Channelopathies can also lead to ataxia, especially episodic ataxia. Although phenotypic characteristics are an aid to the clinician, a definitive diagnosis is usually made only through genotypic or molecular studies. Genetic counseling is necessary for the testing of symptomatic and asymptomatic individuals. No effective treatment is yet available for most ataxic syndromes, except for ataxia with isolated vitamin E deficiency and the episodic ataxias.

Marinesco-Sjögren syndrome: clinical and magnetic resonance imaging features in three children

The authors describe clinical and MRI features of a girl and two boys, aged 9, 17 and 19 years, respectively, with Marinesco-Sjögren syndrome. The clinical findings included the major features of the syndrome, including growth deficiency, ataxia, cataracts, hypogonadism (in two) and seizures (in two). Truncal hypotonia (in three), microcephaly (in two) and leg spasticity (in two) were also present. MRI showed a very small cerebellar vermis in all three patients, various supratentorial abnormalities, an apparently small anterior pituitary gland in two and the absence of a posterior pituitary gland in all three. The MRI features are similar to the few reported pathologic findings for persons with Marinesco-Sjögren syndrome. MRI may be helpful in the early diagnosis of the disorder.

Marinesco-Sjögren syndrome: clinical and magnetic resonance imaging features in three children

The authors describe clinical and MRI features of a girl and two boys, aged 9, 17 and 19 years, respectively, with Marinesco-Sjögren syndrome. The clinical findings included the major features of the syndrome, including growth deficiency, ataxia, cataracts, hypogonadism (in two) and seizures (in two). Truncal hypotonia (in three), microcephaly (in two) and leg spasticity (in two) were also present. MRI showed a very small cerebellar vermis in all three patients, various supratentorial abnormalities, an apparently small anterior pituitary gland in two and the absence of a posterior pituitary gland in all three. The MRI features are similar to the few reported pathologic findings for persons with Marinesco-Sjögren syndrome. MRI may be helpful in the early diagnosis of the disorder.

Cerebellar dysplasia and unilateral cataract in Marinesco-Sjögren syndrome

The classic features of Marinesco-Sjögren syndrome include bilateral cataracts, cerebellar ataxia, and mental deficiency with an autosomal recessive inheritance pattern. Weakness and a variety of other characteristics are present inconsistently. A limited number of neuroimaging studies have indicated that cerebellar hypoplasia is the most common finding. We report a patient with near normal intelligence, unilateral cataract, and the previously unreported magnetic resonance imaging findings of cerebellar dysplasia, arachnoid cyst, and absent septum pellucidum. A review of the literature suggests significant heterogeneity in the Marinesco-Sjögren syndrome.

Motion perception deficits from midline cerebellar lesions in human

Although visual motion processing is commonly thought to be mediated solely by visual cortical areas, this human lesion study suggests that the cerebellum also has a role. We found motion direction discrimination deficits in a group of patients with acute midline cerebellar lesions. Unlike normals and patients with hemispheric cerebellar lesions, these patients with midline lesions were unable to discern a global motion vector in a local stochastic motion display. This resembles the perceptual defect reported following cortical area MT lesions in primates. This motion perception deficit may result from damage to a cerebellar mechanism involved in perceptual stabilization. Disruption of this comparator mechanism is sufficient to produce a severe motion perception deficit even though cortical visual processing mechanisms are still intact.

Optic atrophy in Marinesco-Sjögren syndrome: an additional ocular feature. Report of three cases in two families

Marinesco-Sjögren syndrome (MSS) is a rare inherited disease with neurological and ocular manifestations. The latter include bilateral cataracts and, less frequently, nystagmus and strabismus. The authors report here three cases of MSS syndrome, all with optic atrophy, an additional ocular feature not hitherto described in this syndrome.