"Ears of the Lynx" MRI Sign Is Associated with SPG11 and SPG15 Hereditary Spastic Paraplegia.

BACKGROUND AND PURPOSE: The "ears of the lynx" MR imaging sign has been described in case reports of hereditary spastic paraplegia with a thin corpus callosum, mostly associated with mutations in the spatacsin vesicle trafficking associated gene, causing Spastic Paraplegia type 11 (SPG11). This sign corresponds to long T1 and T2 values in the forceps minor of the corpus callosum, which appears hyperintense on FLAIR and hypointense on T1-weighted images. Our purpose was to determine the sensitivity and specificity of the ears of the lynx MR imaging sign for genetic cases compared with common potential mimics. MATERIALS AND METHODS: Four independent raters, blinded to the diagnosis, determined whether the ears of the lynx sign was present in each of a set of 204 single anonymized FLAIR and T1-weighted MR images from 34 patients with causal mutations associated with SPG11 or Spastic Paraplegia type 15 (SPG15). 34 healthy controls, and 34 patients with multiple sclerosis. RESULTS: The interrater reliability for FLAIR images was substantial (Cohen κ, 0.66-0.77). For these images, the sensitivity of the ears of the lynx sign across raters ranged from 78.8 to 97.0 and the specificity ranged from 90.9 to 100. The accuracy of the sign, measured by area under the receiver operating characteristic curve, ranged from very good (87.1) to excellent (93.9). CONCLUSIONS: The ears of the lynx sign on FLAIR MR imaging is highly specific for the most common genetic subtypes of hereditary spastic paraplegia with a thin corpus callosum. When this sign is present, there is a high likelihood of a genetic mutation, particularly associated with SPG11 or SPG15, even in the absence of a family history.

Deep brain stimulation in early Parkinson's disease: enrollment experience from a pilot trial.

BACKGROUND: Deep brain stimulation (DBS) of the subthalamic nucleus is an accepted therapy for advanced Parkinson's disease (PD). In animal models, pharmacologic ablation and stimulation of the subthalamic nucleus have resulted in clinical improvement and, in some cases, improved survival of dopaminergic neurons. DBS has not been studied in the early stages of PD, but early application should be explored to evaluate safety, efficacy, and the potential to alter disease progression. METHODS: We are conducting a prospective, randomized, single-blind clinical trial of optimal drug therapy (ODT) compared to medication plus DBS (ODT + DBS) in subjects with Hoehn & Yahr Stage II idiopathic PD who are without motor fluctuations or dementia. We report here subject screening, enrollment, baseline characteristics, and adverse events. RESULTS: 30 subjects (average age 60 ± 6.9 years, average duration of medicine 2.1 ± 1.3 years, average UPDRS-III scores 14.9 on medication and 27.0 off medication) are enrolled in the ongoing study. Twelve of 15 subjects randomized to DBS experienced perioperative adverse events, the majority of which were related to the procedure or device and resolved without sequelae. Frequently reported adverse events included wound healing problems, headache, edema, and confusion. CONCLUSION: This report demonstrates that subjects with early stage PD can be successfully recruited, consented and retained in a long-term clinical trial of DBS. Our ongoing pilot investigation will provide important preliminary safety and tolerability data concerning the application of DBS in early stage PD.

Novel THAP1 sequence variants in primary dystonia.

BACKGROUND: THAP1 encodes a transcription factor (THAP1) that harbors an atypical zinc finger domain and regulates cell proliferation. An exon 2 insertion/deletion frameshift mutation in THAP1 is responsible for DYT6 dystonia in Amish-Mennonites. Subsequent screening efforts in familial, mainly early-onset, primary dystonia identified additional THAP1 sequence variants in non-Amish subjects. OBJECTIVE: To examine a large cohort of subjects with mainly adult-onset primary dystonia for sequence variants in THAP1. METHODS: With high-resolution melting, all 3 THAP1 exons were screened for sequence variants in 1,114 subjects with mainly adult-onset primary dystonia, 96 with unclassified dystonia, and 600 controls (400 neurologically normal and 200 with Parkinson disease). In addition, all 3 THAP1 exons were sequenced in 200 subjects with dystonia and 200 neurologically normal controls. RESULTS: Nine unique melting curves were found in 19 subjects from 16 families with primary dystonia and 1 control. Age at dystonia onset ranged from 8 to 69 years (mean 48 years). Sequencing identified 6 novel missense mutations in conserved regions of THAP1 (G9C [cervical, masticatory, arm], D17G [cervical], F132S [laryngeal], I149T [cervical and generalized], A166T [laryngeal], and Q187K [cervical]). One subject with blepharospasm and another with laryngeal dystonia harbored a c.-42C>T variant. A c.57C>T silent variant was found in 1 subject with segmental craniocervical dystonia. An intron 1 variant (c.71+9C>A) was present in 7 subjects with dystonia (7/1,210) but only 1 control (1/600). CONCLUSIONS: A heterogeneous collection of THAP1 sequence variants is associated with varied anatomical distributions and onset ages of both familial and sporadic primary dystonia.

Familial mesial temporal lobe epilepsy maps to chromosome 4q13.2-q21.3.

PURPOSE: To report results of linkage analysis in a large family with autosomal dominant (AD) familial mesial temporal lobe epilepsy (FMTLE). BACKGROUND: Although FMTLE is a heterogeneous syndrome, one important subgroup is characterized by a relatively benign course, absence of antecedent febrile seizures, and absence of hippocampal sclerosis. These patients have predominantly simple partial seizures (SPS) and infrequent complex partial seizures (CPS), and intense and frequent déjà vu phenomenon may be the only manifestation of this epilepsy syndrome. No linkage has been described in this form of FMTLE. METHODS: We identified a four-generation kindred with several affected members meeting criteria for FMTLE and enrolled 21 individuals who gave informed consent. Every individual was personally interviewed and examined; EEG and MRI studies were performed on three affected subjects. DNA was extracted from every enrolled individual. We performed a genome-wide search using an 8 cM panel and fine mapping was performed in the regions with a multipoint lod score >1. We sequenced the highest priority candidate genes. RESULTS: Inheritance was consistent with AD mode with reduced penetrance. Eleven individuals were classified as affected with FMTLE and we also identified two living asymptomatic individuals who had affected offspring. Seizure semiologies included predominantly SPS with déjà vu feeling, infrequent CPS, and rare secondarily generalized tonic-clonic seizures. No structural abnormalities, including hippocampal sclerosis, were detected on MRI performed on three individuals. Genetic analysis detected a group of markers with lod score >3 on chromosome 4q13.2-q21.3 spanning a 7 cM region. No ion channel genes are predicted to be localized within this locus. We sequenced all coding exons of sodium bicarbonate cotransporter (SLC4A) gene, which plays an important role in tissue excitability, and cyclin I (CCNI), because of its role in the cell migration and possibility of subtle cortical abnormalities. No disease-causing mutations were identified in these genes. CONCLUSION: We report identification of a genetic locus for familial mesial temporal lobe epilepsy. The identification of a disease-causing gene will contribute to our understanding of the pathogenesis of temporal lobe epilepsies.

Genetic variants in the IMPA2 gene do not confer increased risk of febrile seizures in Caucasian patients.

Pathogenesis of febrile seizures (FS), causing the most common of types of seizures in children, remains unknown. Genetic factors appear to play a pivotal role and FS can be inherited as a monogenic or genetically complex disorder. Several risks factors have been proposed but many of the previously reported genetic associations were not replicated. Non-coding polymorphisms in the myo-inositol monophosphatase 2 gene (IMPA2) have been suggested as a susceptibility factor for FS in Japanese patients. It is unknown whether genetic variants in the same gene constitute a risk factor for FS in other ethnic groups because the frequency of FS is significantly higher in Japanese children than in Caucasian patients. We investigated the role of the IMPA2 gene in a cohort of 96 unrelated Caucasian subjects with a history of FS. We did not identify any significant differences in genotypes of cases and matched controls; no mutations or non-synonymous polymorphisms were detected in these individuals. Our data suggest that the genetic variants in the IMPA2 gene are not associated with a risk of FS in Caucasian patients and patients from various genetic groups are likely to have different genetic causes of FS.

Familial genetic predisposition, epilepsy localization and antecedent febrile seizures.

PURPOSE: The magnitude of genetic influence in epilepsy may vary in relation to epilepsy classification and localization and factors such as antecedent febrile seizures. We assessed this genetic influence in a large epilepsy population. METHODS: Patients with established epilepsy diagnosis evaluated in the Vanderbilt Epilepsy Program were systematically questioned about family history of epilepsy and febrile seizures, prior febrile seizures and other risk factors for epilepsy. RESULTS: A total of 1994 patients with epilepsy and reliable family history were identified. Patients with prior febrile seizures (FS) were more likely to have a family history of febrile seizures than those without prior FS (p<0.000001) and also had a greater proportion of relatives with febrile seizures. The groups did not differ with respect to family history of epilepsy. Patients with generalized epilepsy were more likely to have first and second degree relatives with epilepsy than those with partial epilepsy (40.2% versus 31.2%, p=0.001), and also had a greater proportion of affected first degree relatives (p<0.000001). The proportion of first degree relatives affected with epilepsy was higher than local published prevalence, for both groups. CONCLUSION: Susceptibility for febrile seizures with subsequent epilepsy may be genetically distinct from susceptibility for afebrile seizures alone. Although family history of epilepsy was more likely with generalized epilepsy, a familial tendency was considerable in partial epilepsy.

Laing early onset distal myopathy: slow myosin defect with variable abnormalities on muscle biopsy.

BACKGROUND: Laing early onset distal myopathy (MPD1) is an autosomal dominant myopathy caused by mutations within the slow skeletal muscle fibre myosin heavy chain gene, MYH7. It is allelic with myosin storage myopathy, with the commonest form of familial hypertrophic cardiomyopathy, and with one form of dilated cardiomyopathy. However, the clinical picture of MPD1 is distinct from these three conditions. OBJECTIVE: To collate and discuss the histological features reported in the muscle biopsies of MPD1 patients and to outline the clinical features. RESULTS: The phenotype of MPD1 was consistent, with initial weakness of great toe/ankle dorsiflexion, and later development of weakness of finger extension and neck flexion. Age of onset was the only variable, being from birth up to the 20 s, but progression was always very slow. The pathological features were variable. In this retrospective series, there were no pathognomonic diagnostic features, although atrophic type I fibres were found in half the families. Rimmed vacuoles are consistently seen in all other distal myopathies with the exception of Myoshi distal myopathy. However, they were found in a minority of patients with MPD1, and were not prominent when present. Immunohistochemical staining for slow and fast myosin showed co-expression of slow and fast myosin in some type I fibres, possibly indicating a switch to type II status. This may be a useful aid to diagnosis. CONCLUSIONS: The pathological findings in MPD1 are variable and appear to be affected by factors such as the specific muscle biopsied, the age of the patient at biopsy, and the duration of disease manifestations.

Systematic isolation and characterization of cDNAs encoding AAA proteins from human brain.

BACKGROUND: The AAA (ATPases Associated with various cellular Activities) domain characterizes a diverse superfamily of proteins. Mutations in genes encoding AAA-domains cause a variety of human diseases including cystic fibrosis, Zellweger syndrome, adrenomyeloneuropathy, and dystonia. Recently, mutations in two AAA-containing proteins paraplegin and spastin have been shown to cause two types of hereditary spastic paraplegia (HSP). The HSPs are genetically heterogeneous degenerative spinal cord disorders characterized by lower extremity weakness and spasticity. Clinical similarity between various genetic types of HSP led us to propose that different genetic types of HSP were due to common biochemical abnormalities including disturbances in related proteins. For this reason, we sought to identify novel AAA-containing proteins as potential candidates for HSP and related neurodegnerative disorders. We used degenerative PCR, based on the conserved AAA peptide sequence to systematically clone and characterize AAA genes expressed in human brain. RESULTS: We analyzed 646 clones and identified 19 known AAA-containing proteins including spastin and paraplegin, AAA-containing genes that cause HSP. In addition, we identified 14 unique DNA inserts representing novel putative AAA-containing proteins. Four of these novel genes are hypothetical AAA proteins and the rest of novel clones matched sequences of yet uncharacterized expressed sequence tags (ESTs). CONCLUSION: Fourteen novel AAA-containing proteins are potential candidates for human diseases including degenerative neurologic disorders, and their further analysis is ongoing (Tab. 1, Fig. 1, Ref. 22).

Spinal cord magnetic resonance imaging in autosomal dominant hereditary spastic paraplegia.

Hereditary spastic paraplegia (HSP) is a genetically heterogeneous group of neurodegenerative disorders characterized by progressive lower extremity weakness and spasticity. HSP pathology involves axonal degeneration that is most pronounced in the terminal segments of the longest descending (pyramidal) and ascending (dorsal columns) tracts. In this study, we compared spinal cord magnetic resonance imaging (MRI) in 13 HSP patients with four different types of autosomal dominant hereditary spastic paraplegia (SPG3A, SPG4, SPG6, and SPG8) with age-matched control subjects. The cross-section area of HSP subjects at cervical level C2 was 59.42 +/- 12.57 mm2 and at thoracic level T9 was 28.58 +/- 5.25 mm2. Both of these values were less than in the healthy controls (p < 0.001). The degree of cord atrophy was more prominent in patients with SPG6 and SPG8 who had signs of severe cord atrophy (47.60 +/- 6.58 mm2 at C2, 21.40 +/- 2.4 mm2 at T9) than in subjects with SPG3 and SPG4 (66.0 +/- 8.94 mm2 at C2, p < 0.02; 31.75 +/- 2.76 mm2 at T9, p < 0.001). These observations indicate that spinal cord atrophy is a common finding in the four genetic types of HSP. Spinal cord atrophy was more severe in SPG6 and SPG8 HSP subjects than in other types of HSP we studied. This may suggest a different disease mechanism with more prominent axonal degeneration in these two types of HSP when compared with HSP due to spastin and atlastin mutations.

Novel autosomal dominant mandibulofacial dysostosis with ptosis: clinical description and exclusion of TCOF1.

BACKGROUND: Treacher Collins syndrome (TCS), the most common type of mandibulofacial dysostosis (MFD), is genetically homogeneous. Other types of MFD are less common and, of these, only the Bauru type of MFD has an autosomal dominant (AD) mode of inheritance established. Here we report clinical features of a kindred with a unique AD MFD with the exclusion of linkage to the TCS locus (TCOF1) on chromosome 5q31-q32. METHODS: Six affected family members underwent a complete medical genetics physical examination and two affected subjects had skeletal survey. All available medical records were reviewed. Linkage analysis using the markers spanning the TCOF1 locus was performed. One typically affected family member had a high resolution karyotype. RESULTS: Affected subjects had significant craniofacial abnormalities without any significant acral changes and thus had a phenotype consistent with a MFD variant. Distinctive features included hypoplasia of the zygomatic complex, micrognathia with malocclusion, auricular abnormalities with conductive hearing loss, and ptosis. Significantly negative two point lod scores were obtained for markers spanning the TCOF1 locus, excluding the possibility that the disease in our kindred is allelic with TCS. High resolution karyotype was normal. CONCLUSIONS: We report a kindred with a novel type of MFD that is not linked to the TCOF1 locus and is also clinically distinct from other types of AD MFD. Identification of additional families will facilitate identification of the gene causing this type of AD MFD and further characterisation of the clinical phenotype.

Spastic paraplegia, ataxia, mental retardation (SPAR): a novel genetic disorder.

OBJECTIVE: To describe a kindred with a dominantly inherited neurologic disorder manifested either as uncomplicated spastic paraplegia or ataxia, spastic paraplegia, and mental retardation. METHODS: Neurologic examinations and molecular genetic analysis (exclusion of known SCA and HSP genes and loci; and trinucleotide repeat expansion detection [RED]) were performed in six affected and four unaffected subjects in this family. MRI, electromyography (EMG), and nerve conduction studies were performed in three affected subjects. RESULTS: The phenotype of this dominantly inherited syndrome varied in succeeding generations. Pure spastic paraplegia was present in the earliest generation; subsequent generations had ataxia and mental retardation. MRI showed marked atrophy of the spinal cord in all patients and cerebellar atrophy in those with ataxia. Laboratory analysis showed that the disorder was not caused by mutations in genes that cause SCA-1, SCA-2, SCA-3, SCA-6, SCA-7, SCA-8, and SCA-12; not linked to other known loci for autosomal dominant ataxia (SCA-4, SCA-5, SCA-10, SCA-11, SCA-13, SCA-14, and SCA-16); and not linked to known loci for autosomal dominant hereditary spastic paraplegia (HSP) (SPG-3, SPG-4, SPG-6, SPG-8, SPG-9, SPG-10, SPG-12, and SPG-13) or autosomal recessive HSP SPG-7. Analysis of intergenerational differences in age at onset of symptoms suggests genetic anticipation. Using RED, the authors did not detect expanded CAG, CCT, TGG, or CGT repeats that segregate with the disease. CONCLUSIONS: The authors describe an unusual, dominantly inherited neurologic disorder in which the phenotype (pure spastic paraplegia or spastic ataxia with variable mental retardation) differed in subsequent generations. The molecular explanation for apparent genetic anticipation does not appear to involve trinucleotide repeat expansion.

Mutations in a newly identified GTPase gene cause autosomal dominant hereditary spastic paraplegia.

The hereditary spastic paraplegias (HSPs; Strümpell-Lorrain syndrome, MIM number 18260) are a diverse class of disorders characterized by insidiously progressive lower-extremity spastic weakness (reviewed in refs. 1-3). Eight autosomal dominant HSP (ADHSP) loci have been identified, the most frequent of which is that linked to the SPG4 locus on chromosome 2p22 (found in approximately 42%), followed by that linked to the SPG3A locus on chromosome 14q11-q21 (in approximately 9%). Only SPG4 has been identified as a causative gene in ADHSP. Its protein (spastin) is predicted to participate in the assembly or function of nuclear protein complexes. Here we report the identification of mutations in a newly identified GTPase gene, SPG3A, in ADHSP affected individuals.

Retinitis pigmentosa, growth hormone deficiency, and acromelic skeletal dysplasia in two brothers: possible familial RHYNS syndrome.

Here we report two brothers with retinitis pigmentosa, growth hormone deficiency, and acromelic skeletal dysplasia. We propose that their clinical picture is consistent with RHYNS syndrome (retinitis pigmentosa, hypopituitarism, nephronophthisis, and skeletal dysplasia) and that they represent the first instance of a familial occurrence of this syndrome. The presence of RHYNS in two siblings supports an autosomal recessive mode of inheritance; however, since all four known cases were male, an X-linked mode of inheritance cannot be excluded. The combination of clinical features found in these affected males is unique and supports the existence of RHYNS syndrome as a separate and distinct entity.

Prenatal diagnosis of hereditary spastic paraplegia.

Hereditary spastic paraplegia (HSP) is a degenerative neurologic disorder that causes progressive, often severe, spastic weakness in the legs. Autosomal dominant HSP is a highly penetrant, genetically heterogeneous disorder with loci present on chromosomes 2p21-24, 2q24-34, 8q23-24, 10q23.3-24, 12q13, 14q12-23, 15q11-14 and 19q13.1. We identified a large HSP kindred in which the disorder was tightly linked to chromosome 14q12-23. We tested chorionic villus DNA samples of two at-risk fetuses for inheritance of microsatellite polymorphisms flanking and within this locus that segregated with the disease in this family. Whereas samples from the first fetus showed inheritance of a haplotype segregating with the disease allele (indicating high risk of developing HSP), samples from the second fetus showed inheritance of a haplotype segregating with the normal allele (indicating low risk of developing HSP). This is the first report of prenatal testing for HSP. Published in 2001 by John Wiley & Sons, Ltd.

Ethical principles and pitfalls of genetic testing for dementia.

Progress in the genetics of dementing disorders and the availability of clinical tests for practicing physicians increase the need for a better understanding of multifaceted issues associated with genetic testing. The genetics of dementia is complex, and genetic testing is fraught with many ethical concerns. Genetic testing can be considered for patients with a family history suggestive of a single gene disorder as a cause of dementia. Testing of affected patients should be accompanied by competent genetic counseling that focuses on probabilistic implications for at-risk first-degree relatives. Predictive testing of at-risk asymptomatic patients should be modeled after presymptomatic testing for Huntington's disease. Testing using susceptibility genes has only a limited diagnostic value at present because potential improvement in diagnostic accuracy does not justify potentially negative consequences for first-degree relatives. Predictive testing of unaffected subjects using susceptibility genes is currently not recommended because individual risk cannot be quantified and there are no therapeutic interventions for dementia in presymptomatic patients.

Treatment of Wilson's disease with zinc. XVII: treatment during pregnancy.

Therapy of Wilson's disease continues to evolve. In 1997, zinc acetate was added to the list of drugs approved by the Food and Drug Administration, which includes penicillamine and trientine. The mechanism of zinc's anticopper action is unique. It induces intestinal cell metallothionein, which binds copper and prevents its transfer into blood. As intestinal cells die and slough, the contained copper is eliminated in the stool. Thus, zinc prevents the intestinal absorption of copper. It is universally agreed that pregnant Wilson's disease patients should remain on anticopper therapy during pregnancy. There are numerous reports of such patients stopping penicillamine therapy to protect their fetus from teratogenicity, only to undergo serious deterioration and even death from renewed copper toxicity. Penicillamine and trientine have teratogenic effects in animals, and penicillamine has known teratogenic effects in humans. In this report we discuss the results of 26 pregnancies in 19 women who were on zinc therapy throughout their pregnancy. The evidence is good that zinc protects the health of the mother during pregnancy. Fetal outcomes were generally quite good, although one baby had a surgically correctable heart defect and one had microcephaly.

Phenotypic analysis of autosomal dominant hereditary spastic paraplegia linked to chromosome 8q.

OBJECTIVE: To describe clinical, electrophysiologic, neuroimaging, and muscle biopsy features in a hereditary spastic paraplegia (HSP) kindred linked to a new HSP locus on chromosome 8q. BACKGROUND: HSP is a genetically diverse group of disorders characterized by insidiously progressive spastic weakness in the legs. We recently analyzed a Caucasian kindred with autosomal dominant HSP and identified tight linkage to a novel HSP locus on chromosome 8q23-24. METHODS: Clinical analysis, nerve conduction studies, electromyography, somatosensory evoked potentials, MRI of brain and spinal cord, and muscle biopsy for mitochondrial analysis were performed in members of the first HSP kindred linked to chromosome 8q. RESULTS: Fifteen individuals showed insidiously progressive spastic paraparesis beginning between ages 22 and 60 years (average, 37.2 years). Spinal cord MRI in 1 moderately affected subject showed significant atrophy of the thoracic spinal cord as determined by cross-sectional area measurements. Somatosensory evoked potential recording, electromyography, nerve conduction studies, and muscle biopsy, including histochemical and biochemical analysis of mitochondrial function, were normal. CONCLUSIONS: The phenotype in this family is that of typical, but severe, uncomplicated HSP. Other than apparently increased severity, there were no clinical features that distinguished this family from autosomal dominant HSP linked to loci on chromosomes 2p, 14q, and 15q. This clinical similarity between different genetic types of autosomal dominant HSP raises the possibility that genes responsible for these clinically indistinguishable disorders may participate in a common biochemical cascade. Normal results of muscle histochemical and biochemical analysis suggest that mitochondrial disturbance, a feature of chromosome 16-linked autosomal recessive HSP due to paraplegin gene mutations, is not a feature of chromosome 8q-linked autosomal dominant HSP and may not be a common factor of HSP in general.