Levodopa-carbidopa intestinal gel infusion (LCIG) in Parkinson disease with genetic mutations.

BACKGROUND: Levodopa-carbidopa intestinal gel infusion (LCIG) is a therapeutic option for advanced Parkinson disease (PD) patients with troublesome motor complications, unresponsive to conventional oral treatment. There is some evidence to suggest that the genetic background may influence the clinical presentation and rate of progression of PD. Whether the genetic background influences the outcome of device-assisted therapies is currently debated. Some studies have investigated the effectiveness of deep brain stimulation (DBS) in PD patients with different genetic background, while evidence is lacking regarding LCIG. METHODS: A cohort of LCIG patients underwent genetic testing. The motor and neuropsychological outcomes of LCIG were retrospectively analyzed. RESULTS: Fifty-six patients were analyzed, nine of them (15%) had at least one mutation/variant in a PD-associated gene: five GBA1, two SNCA, one LRRK2, one PRKN; 13 (23%) carried the BDNF Val66Met polymorphism. The mean duration of follow-up was 4.9 ± 2.6 years. There were no significant differences in motor or neuropsychological outcomes between patients with and without these gene mutations/variants. No cognitive worsening was observed at follow-up among GBA-PD patients, and they responded well to LCIG in terms of motor symptoms. CONCLUSIONS: Overall, we observed a significant benefit in terms of motor complications in our cohort, including patients carrying genetic mutations/variants. Due to the small sample and limited number of patients carrying genetic mutations/variants, no definitive conclusions can be drawn yet on the genotype impact on LCIG outcome. A careful selection of patients, regardless of the genetic background, is pivotal for an optimal outcome of LCIG.

Familial aggregation in Progressive Supranuclear Palsy and Corticobasal Syndrome.

BACKGROUND: Studies on familial aggregation might be of help to evaluate whether the genetic background has a key role in Progressive Supranuclar Palsy (PSP) and Corticobasal Syndrome (CBS). Only a few studies are available. OBJECTIVE: To evaluate the prevalence of positive family history (FH) in PSP and CBS in a large sample of patients. METHODS: Two hundred and thirty patients and 110 controls entered the study. Patients underwent an extensive clinical, neurological and neuropsychological assessment as well as a structural brain imaging study. A clinical follow-up further confirmed the diagnosis. Familial aggregation was carefully recorded by a standardised questionnaire. RESULTS: One hundred and twenty-nine PSP (age at onset = 66.6 +/- 7.3, female = 46.1%) and 101 CBS (age at onset = 62.8 +/- 8.9, female = 41.6%) were consecutively enrolled. Positive FH was found in 31.8% of PSP (n = 41) and in 31.7% of CBS (n = 32). Familial aggregation was lower in the age-matched control group compared to patient group (21.8%, P = 0.05). Patients with PSP had higher positive FH for Parkinsonism (63.4%) when compared to FH for dementia (36.6%). In CBS, FH was equally distributed between Parkinsonism (53.1%) and dementia (46.9%). In addition, FH was not associated with age at disease onset in PSP (FH+ versus FH-, 67.0 +/- 7.3 vs. 66.7 +/- 7.1, P = 0.788) and in CBS (62.6 +/- 7.9 vs. 62.9 +/- 9.5, P= 0.877). CONCLUSIONS: These results argue for familial aggregation in PSP and CBS, further underlying the importance of genetic background in these disorders. Further studies on possible genetic modulators or genetic epistasis contributing to PSP and CBS development are warranted.

Haplotypes and gene expression implicate the MAPT region for Parkinson disease: the GenePD Study.

BACKGROUND: Microtubule-associated protein tau (MAPT) has been associated with several neurodegenerative disorders including forms of parkinsonism and Parkinson disease (PD). We evaluated the association of the MAPT region with PD in a large cohort of familial PD cases recruited by the GenePD Study. In addition, postmortem brain samples from patients with PD and neurologically normal controls were used to evaluate whether the expression of the 3-repeat and 4-repeat isoforms of MAPT, and neighboring genes Saitohin (STH) and KIAA1267, are altered in PD cerebellum. METHODS: Twenty-one single-nucleotide polymorphisms (SNPs) in the region of MAPT on chromosome 17q21 were genotyped in the GenePD Study. Single SNPs and haplotypes, including the H1 haplotype, were evaluated for association to PD. Relative quantification of gene expression was performed using real-time RT-PCR. RESULTS: After adjusting for multiple comparisons, SNP rs1800547 was significantly associated with PD affection. While the H1 haplotype was associated with a significantly increased risk for PD, a novel H1 subhaplotype was identified that predicted a greater increased risk for PD. The expression of 4-repeat MAPT, STH, and KIAA1267 was significantly increased in PD brains relative to controls. No difference in expression was observed for 3-repeat MAPT. CONCLUSIONS: This study supports a role for MAPT in the pathogenesis of familial and idiopathic Parkinson disease (PD). Interestingly, the results of the gene expression studies suggest that other genes in the vicinity of MAPT, specifically STH and KIAA1267, may also have a role in PD and suggest complex effects for the genes in this region on PD risk.

Lrrk2 R1441C parkinsonism is clinically similar to sporadic Parkinson disease.

OBJECTIVE: Leucine-rich repeat kinase 2 (LRRK2) mutations are the most common cause of Parkinson disease (PD). Several dominantly inherited pathogenic substitutions have been identified in different domains of the Lrrk2 protein. Herein, we characterize the clinical and genetic features associated with Lrrk2 p.R1441C. METHODS: We identified 33 affected and 15 unaffected LRRK2 c.4321C>T (p.R1441C) mutation carriers through an international consortium originating from three continents. The age-specific cumulative incidence of PD was calculated by Kaplan-Meier analysis. RESULTS: The clinical presentation of Lrrk2 p.R1441C carriers was similar to sporadic PD and Lrrk2 p.G2019S parkinsonism. The mean age at onset for parkinsonism was 60 years, range 30-79 years; fewer than 20% of the patients had symptoms before the age 50 years, while by 75 years >90% of them had developed symptoms. Haplotype analysis suggests four independent founders for the p.R1441C mutation. CONCLUSIONS: The distribution in age at onset and clinical features in Lrrk2 p.R1441C patients are similar to idiopathic and Lrrk2 p.G2019S parkinsonism. Several independent founders of the p.R1441C substitution suggest this site is prone to recurrent mutagenesis.

ATP13A2 missense mutations in juvenile parkinsonism and young onset Parkinson disease.

OBJECTIVE: To assess the prevalence, nature, and associated phenotypes of ATP13A2 gene mutations among patients with juvenile parkinsonism (onset <21 years) or young onset (between 21 and 40 years) Parkinson disease (YOPD). METHODS: We studied 46 patients, mostly from Italy or Brazil, including 11 with juvenile parkinsonism and 35 with YOPD. Thirty-three cases were sporadic and 13 had positive family history compatible with autosomal recessive inheritance. Forty-two had only parkinsonian signs, while four (all juvenile-onset) had multisystemic involvement. The whole ATP13A2 coding region (29 exons) and exon-intron boundaries were sequenced from genomic DNA. RESULTS: A novel homozygous missense mutation (Gly504Arg) was identified in one sporadic case from Brazil with juvenile parkinsonism. This patient had symptoms onset at age 12, levodopa-responsive severe akinetic-rigid parkinsonism, levodopa-induced motor fluctuations and dyskinesias, severe visual hallucinations, and supranuclear vertical gaze paresis, but no pyramidal deficit nor dementia. Brain CT scan showed moderate diffuse atrophy. Furthermore, two Italian cases with YOPD without atypical features carried a novel missense mutation (Thr12Met, Gly533Arg) in single heterozygous state. CONCLUSIONS: We confirm that ATP13A2 homozygous mutations are associated with human parkinsonism, and expand the associated genotypic and clinical spectrum, by describing a homozygous missense mutation in this gene in a patient with a phenotype milder than that initially associated with ATP13A2 mutations (Kufor-Rakeb syndrome). Our data also suggest that ATP13A2 single heterozygous mutations might be etiologically relevant for patients with YOPD and further studies of this gene in Parkinson disease are warranted.

Evaluation of LRRK2 G2019S penetrance: relevance for genetic counseling in Parkinson disease.

We report the results of a family-based study of LRRK2 G2019S penetrance in Parkinson disease. We studied 19 families identified through the analysis of unrelated consecutive patients. The cumulative incidence of the disease was 15% at 60 years, 21% at 70 years, and 32% at 80 years. This study provides accurate estimates of G2019S penetrance by minimizing the selection bias.

Herbicide exposure modifies GSTP1 haplotype association to Parkinson onset age: the GenePD Study.

BACKGROUND: Polymorphisms in the glutathione S-transferase pi gene (GSTP1), encoding GSTP1-1, a detoxification enzyme, may increase the risk of Parkinson disease (PD) with exposure to pesticides. Using the GenePD Study sample of familial PD cases, we explored whether GSTP1 polymorphisms were associated with the age at onset of PD symptoms and whether that relation was modified by exposure to herbicides. METHODS: Seven single-nucleotide polymorphisms (SNPs) were genotyped and tested for association with PD onset age in men in three strata: no exposure to herbicides, residential exposure to herbicides, and occupational exposure to herbicides. Haplotypes were similarly evaluated in stratified analyses. RESULTS: Three SNPs were associated with PD onset age in the group of men occupationally exposed to herbicides. Three additional SNPs had significant trends for the association of PD onset age across the herbicide exposure groups. Haplotype results also provided evidence that the relation between GSTP1 and onset age is modified by herbicide exposure. One haplotype was associated with an approximately 8-years-earlier onset in the occupationally exposed group and a 2.8-years-later onset in the nonexposed group. CONCLUSIONS: Herbicide exposure may be an effect modifier of the relation between glutathione S-transferase pi gene polymorphisms and onset age in familial PD.

BDNF genetic variants are associated with onset age of familial Parkinson disease: GenePD Study.

Brain-derived neurotrophic factor (BDNF) stimulates neuronal growth and protects nigral dopamine neurons in animal models of Parkinson disease (PD). Therefore, BDNF is a candidate gene for PD. The authors investigated five single-nucleotide polymorphisms in 597 cases of familial PD. Homozygosity for the rare allele of the functional BDNF G196A (Val66Met) variant was associated with a 5.3-year older onset age (p = 0.0001). These findings suggest that BDNF may influence PD onset age.

Dopamine transporter imaging study in parkinsonism occurring in fragile X premutation carriers.

The authors studied four patients with parkinsonism carrying the fragile X premutation using SPECT with ([23)I]FP-CIT. They found evidence of preserved presynaptic nigrostriatal function, suggesting that parkinsonism in the X fragile premutation might be related to postsynaptic dopaminergic changes or different neurotransmitter alterations.

The G6055A (G2019S) mutation in LRRK2 is frequent in both early and late onset Parkinson's disease and originates from a common ancestor.

BACKGROUND: Mutations in the gene Leucine-Rich Repeat Kinase 2 (LRRK2) were recently identified as the cause of PARK8 linked autosomal dominant Parkinson's disease. OBJECTIVE: To study recurrent LRRK2 mutations in a large sample of patients from Italy, including early (<50 years) and late onset familial and sporadic Parkinson's disease. RESULTS: Among 629 probands, 13 (2.1%) were heterozygous carriers of the G2019S mutation. The mutation frequency was higher among familial (5.1%, 9/177) than among sporadic probands (0.9%, 4/452) (p<0.002), and highest among probands with one affected parent (8.7%, 6/69) (p<0.001). There was no difference in the frequency of the G2019S mutation in probands with early v late onset disease. Among 600 probands, one heterozygous R1441C but no R1441G or Y1699C mutations were detected. None of the four mutations was found in Italian controls. Haplotype analysis in families from five countries suggested that the G2019S mutation originated from a single ancient founder. The G2019S mutation was associated with the classical Parkinson's disease phenotype and a broad range of onset age (34 to 73 years). CONCLUSIONS: G2019S is the most common genetic determinant of Parkinson's disease identified so far. It is especially frequent among cases with familial Parkinson's disease of both early and late onset, but less common among sporadic cases. These findings have important implications for diagnosis and genetic counselling in Parkinson's disease.

Early-onset parkinsonism associated with PINK1 mutations: frequency, genotypes, and phenotypes.

OBJECTIVE: To assess the prevalence, nature, and associated phenotypes of PINK1 gene mutations in a large series of patients with early-onset (<50 years) parkinsonism. METHODS: The authors studied 134 patients (116 sporadic and 18 familial; 77% Italian) and 90 Italian controls. The whole PINK1 coding region was sequenced from genomic DNA; cDNA was analyzed in selected cases. RESULTS: Homozygous pathogenic mutations were identified in 4 of 90 Italian sporadic cases, including the novel Gln456Stop mutation; single heterozygous truncating or missense mutations were found in another 4 Italian sporadic cases, including two novel mutations, Pro196Leu and Gln456Stop. Pathogenic mutations were not identified in the familial cases. Novel (Gln115Leu) and known polymorphisms were identified with similar frequency in cases and controls. In cases carrying single heterozygous mutation, cDNA analysis detected no additional mutations, and revealed a major pathogenic effect at mRNA level for the mutant C1366T/Gln456Stop allele. All patients with homozygous mutations had very early disease onset, slow progression, and excellent response to l-dopa, including, in some, symmetric onset, dystonia at onset, and sleep benefit, resembling parkin-related disease. Phenotype in patients with single heterozygous mutation was similar, but onset was later. CONCLUSIONS: PINK1 homozygous mutations are a relevant cause of disease among Italian sporadic patients with early-onset parkinsonism. The role of mutations found in single heterozygous state is difficult to interpret. Our study suggests that, at least in some patients, these mutations are disease causing, in combination with additional, still unknown factors.

Molecular analysis of 30 mucopolysaccharidosis type I patients: evaluation of the mutational spectrum in Italian population and identification of 13 novel mutations.

Mucopolysaccharidosis type I (MPS-I orMPS1) is an autosomal recessive condition characterized by a broad range of clinical symptoms. Molecular diagnosis of MPS-I is important for analyzing genotype-phenotype correlation and for selecting patients for innovative therapies. In this study we analyzed 30 Italian MPS-I patients with different phenotypes (20 severe, 6 intermediate, 4 mild) in an attempt to recognize the mutational spectrum in our population and to identify major DNA alterations specific to our country. We identified 93% of mutated alleles (56 out of 60) with the reconstruction of the complete genotype in 26 patients out of 30. Twenty-three different mutations were found, 13 of which are novel while the remaining 10 have been already described. Among the novel mutations we found 5 non conservative missense mutations (A160D, E178K, P183R, G197D, D349Y), one nonsense mutation (C53X), 6 deletions (468-470del3, 486-491del6, 755-759del5, 1251delC, 1839-1867del29, 1902-1903del2), and one splice site mutation (IVS11+5G>A). No common mutation for MPS-I is present in our country. Frequently (40% of the alleles), mutations were found in just one or two patients. However, Q70X, P533R, G51D, and W402X mutations were present in several patients (15%, 13.3%, 13.3%, and 11.6% of the alleles respectively) suggesting a Mediterranean origin of the P533R and G51D mutations. In most cases the patients' genotypes were unique combinations of mutations. The great heterogeneity found in our MPS-I population hampers mutation detection and hinders the genotype-phenotype correlation.

Biochemical and genetic defects underlying human congenital hypotransferrinemia.

INTRODUCTION: Human congenital hypotransferrinemia is a rare disorder characterized by the virtual absence of transferrin in the serum. No information on the causes of the disease is known. MATERIALS AND METHODS: Here we describe the identification of a new case, its treatment and the biochemical and genetic defects underlying the disorder. RESULTS: At diagnosis the patient had serum Tf levels equal to about 1% of the normal values. The treatment with plasma infusions each month allowed a good erythropoiesis and the prevention of iron overload with no need of red blood cell transfusions or iron chelators. In order to define the genetic basis of the disease, we performed a haplotype analysis of the Tf gene region in the 26 individuals forming the proband's family, and demonstrated that the genetic defect is located in the Tf gene and that it is inherited as a recessive trait. Protein analyses indicate that the proband serum contains two transferrin forms: one of 80 kD analogous to the normal one, and a smaller one of 50 kD, which may arise from a specific degradation or be the gene product of a modified allele. CONCLUSION: These data suggest the presence of two Tf alleles carrying genetic defects that cause two distinct abnormalities. One allele causes low expression of an apparently normal protein that probably allowed the survival of the patient in the first years of age. The other allele produces a modified Tf with different biochemical characteristics compared to the normal one.

Generation of a transcription map distal to HLA-F.

We have constructed a transcription map covering a 2 Mb region beginning approximately 1 Mb distal to HLA-F. Cosmids isolated from a chromsome 6 library were positioned by YAC hybridisation, STS and fingerprint analysis. Using direct cDNA selection, exon trapping, and direct genomic sequence analysis, we identified 42 potential exonic fragments in this region. Six fragments corresponded to previously characterised genes, four previously broadly mapped to this region. Five fragments were similar to known genes, eight fragments matched ESTs and 10 of the remaining 23 novel fragments, gave a positive signal on northern analysis. All cDNA fragments were mapped to the YAC and cosmid contig covering the region and with respect to other known genes and STS in this area. The distribution of the cDNA fragments indicated their organisation in three clusters around CpG islands.

The spinal muscular atrophy gene region at 5q13.1 has a paralogous chromosomal region at 6p21.3.

Paralogous regions are duplicated segments of chromosomal DNA that have been acquired during the evolution of the genome. Subsequent divergent evolution of the genes within paralogous regions can lead to the formation of gene families. Here, we report the identification of a region on Chromosome (Chr) 6 at 6p21.3 that is paralogous with the Spinal Muscular Atrophy (SMA) gene region on Chr 5 at 5q13.1. Partial characterization of this region identified nine sequences all of which are highly homologous to DNA sequences of the SMA gene region at 5q13.1. These sequences include four beta-glucuronidase sequences, two retrotransposon sequences, a novel cDNA, a Sequence Tagged Site (STS), and one that is homologous to exon 9 of the Neuronal Apoptosis Inhibitor Protein (NAIP) gene. The 6p21.3 paralogous SMA region may contain genes that are related to those in the SMA region at 5q13.1; however, a direct association of this region with SMA is unlikely given that no linkage of SMA with Chr 6 has been reported.