Abstract Background The relative risk of developing idiopathic PD is 1.5 times greater in men than in women, but an increased female prevalence in LRRK2-carriers has been described in the Ashkenazi ...Jewish population. We report an update about the frequency of major LRRK2 mutations in a large series of consecutive patients with Parkinson's disease (PD), including extensive characterization of clinical features. In particular, we investigated gender-related differences in motor and non-motor symptoms in the LRRK2 population. Methods 2976 unrelated consecutive Italian patients with degenerative Parkinsonism were screened for mutations on exon 41 (G2019S, I2020T) and a subgroup of 1190 patients for mutations on exon 31 (R1441C/G/H). Demographic and clinical features were compared between LRRK2-carriers and non-carriers, and between male and female LRRK2 mutation carriers. Results LRRK2 mutations were identified in 40 of 2523 PD patients (1.6%) and not in other primary parkinsonian syndromes. No major clinical differences were found between LRRK2-carriers and non-carriers. We found a novel I2020L missense variant, predicted to be pathogenic. Female gender was more common amongst carriers than non-carriers (57% vs. 40%; p = 0.01), without any gender-related difference in clinical features. Family history of PD was more common in women in the whole PD group, regardless of their LRRK2 status. Conclusions PD patients with LRRK2 mutations are more likely to be women, suggesting a stronger genetic load compared to idiopathic PD. Further studies are needed to elucidate whether there is a different effect of gender on the balance between genetic and environmental factors in the pathogenesis of PD.
Splicing mutations account for approximately 12% of the 1,890 cystic fibrosis transmembrane conductance regulator (CFTR) gene mutations described in cystic fibrosis (CF). However, their impact on ...pre-mRNA processing frequently remains unclear. An interesting opportunity to study CFTR transcripts in vivo involves the use of RNA from nasal brushings. Through this approach we previously identified a deep-intronic mutation (c.1584+18672A>G) that activates a 104-base pair (bp) out-of-frame pseudoexon by creating a donor splice site. The screening of 230 patients with CF identified c.1584+18672A>G in three additional individuals, demonstrating that it is a recurrent, and potentially overlooked, mutation among Italian patients. Haplotype analysis suggests that it originated from at least two independent events. To characterize the mutation further, a genomic region, including the activated pseudoexon and surrounding intronic sequences, was cloned into an expression vector and transfected into HeLa cells. RT-PCR analysis identified two alternative splicing products, produced by the activation of two different cryptic acceptor splice sites. One included the 104-bp pseudoexon (78.7% of transcripts), and the other led to the inclusion of a 65-bp pseudoexon (21.3% of mRNAs). The allele-specific measurement of wild-type and aberrant splicings from the nasal-brushing RNA of the three probands with genotype F508del/c.1584+18672A>G demonstrated: (1) a low level of pseudoexon inclusion in the F508del transcript (not containing the splicing mutation); (2) residual wild-type splicing in the c.1584+18672A>G mRNA; (3) the degradation of aberrant transcripts; and (4) the relative strength of the different cryptic splice sites. Interestingly, the residual wild-type splicing detected in transcripts bearing the c.1584+18672A>G mutation correlates well with the milder clinical phenotype of patients.
Abstract Background PCR-based diagnostic procedures are not able to characterise 6% of CF alleles. Recently, the application of array-CGH and of CFTR mRNA analysis has allowed the identification of ...new copy number mutations and splicing defects, that account for 2% and 13% of CF alleles, respectively, in the Italian population. Methods Here, we report the characterisation of a large duplication in CFTR gene through different methods: MLPA assay, RT-PCR and high-resolution array-CGH. Results We identified a large duplication, involving exons 6b–16, in a patient heterozygous for F508del mutation. This duplication produces an abnormal transcript with an out of frame addition of 2244 nucleotides and leads to the insertion of 8 amino-acid residues in the protein, followed by a stop codon. Conclusions We propose a wide methodological approach based on MLPA assay, RT-PCR and high-resolution array-CGH to routinely analyse CF patients uncharacterised for one or both CFTR alleles.
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