[Episodic ataxia type 2: a clinical, genetic and radiological study of 10 patients]. / Ataxia episódica tipo 2: estudio clínico, genético y radiológico de 10 pacientes.

OBJECTIVES: To describe a series of patients with episodic ataxia type 2 (EA2), attending to epidemiological, clinical, radiological, and therapeutic variables. MATERIAL AND METHODS: Retrospective revision of patients with molecular diagnosis of EA2 (CACNA1A mutations), between 1988 and 2022. Information achieved from the database of our Movement Disorders clinic. A descriptive statistical analysis was made. RESULTS: Ten patients from five families were analyzed (six women). Median age at diagnosis was 37.5 years-old, with a median diagnostic delay of 20 years. 70% reported familial history of CACNA1A associated symptoms, although 50% presented migraine, epilepsy, dystonia, or neuropsychiatric alterations. Two heterozygous consanguineous patients had homozygotic descendance with infant mortality due to early-onset epileptic encephalopathy type 42. Five pathogenic/probably pathogenic CACNA1A variants were detected. 80% of patients had episodic triggers, being stress the most common. Episodes had a weekly frequency before treatment initiation. Six patients developed chronic ataxia (one patient demand gait support). 50% of patients with neuroimaging presented cerebellar atrophy. Acetazolamide were initiated in 80%, and 75% of them showed improvement of episodic symptoms. Nephrolithiasis was the most frequent side effect. CONCLUSIONS: EA2 has a great intrafamilial and interfamilial phenotypic variability. The most frequent phenotype were weekly episodes of unsteadiness, several hours of length, stress as the main trigger, chronic ataxia and gaze-evoked nystagmus. Acetazolamide is effective, although complications are usual. Neurologist must be alert as diagnostic delay is constant.

TITLE: Ataxia episódica tipo 2: estudio clínico, genético y radiológico de 10 pacientes.Objetivo. Describir una serie de pacientes con ataxia episódica tipo 2 (AE2) según variables epidemiológicas, clínicas, radiológicas y terapéuticas. Material y métodos. Revisión retrospectiva de pacientes con diagnóstico molecular de AE2 (mutación en CACNA1A) entre 1988 y 2022, información recogida de la base de datos de la Unidad de Trastornos del Movimiento de nuestro centro. Se realizó un análisis estadístico descriptivo. Resultados. Se analizó a 10 pacientes procedentes de cinco familias. La mediana de edad en el momento del diagnóstico fue 37,5 años, con un retraso diagnóstico de 20 años. El 50% asociaba epilepsia, migraña, distonía o alteraciones neuropsiquiátricas. El 70% tenía una historia familiar de síntomas asociados a CACNA1A. Dos pacientes heterocigotos consanguíneos tuvieron descendencia homocigota con mortalidad infantil por encefalopatía epiléptica de inicio precoz de tipo 42. Se detectaron cinco variantes diferentes de CACNA1A. El 80% mostró factores desencadenantes, y el estrés fue el más común. La frecuencia episódica más habitual fue semanal. Seis pacientes desarrollaron ataxia interepisódica, aunque sólo uno precisó apoyo en la marcha. El 50% de los pacientes con neuroimagen presentó atrofia cerebelosa. El 80% inició acetazolamida durante el seguimiento, con respuesta a dosis altas en el 75%. La nefrolitiasis fue el efecto adverso más frecuente. La 4-aminopiridina fue una alternativa eficaz. Conclusiones. La AE2 presenta una alta variabilidad fenotípica inter- e intrafamiliar. El fenotipo más frecuente fueron episodios de inestabilidad, de horas de duración, semanales, con estrés como desencadenante, ataxia persistente y nistagmo evocado por la mirada. La acetazolamida, aunque es eficaz, no está exenta de complicaciones. El retraso diagnóstico es muy frecuente.

Ataxia episódica tipo 2: estudio clínico, genético y radiológico de 10 pacientes / Episodic ataxia type 2: a clinical, genetic and radiological study of 10 patients

Objetivo: Describir una serie de pacientes con ataxia episódica tipo 2 (AE2) según variables epidemiológicas, clínicas, radiológicas y terapéuticas. Material y métodos. Revisión retrospectiva de pacientes con diagnóstico molecular de AE2 (mutación en CACNA1A) entre 1988 y 2022, información recogida de la base de datos de la Unidad de Trastornos del Movimiento de nuestro centro. Se realizó un análisis estadístico descriptivo. Resultados: Se analizó a 10 pacientes procedentes de cinco familias. La mediana de edad en el momento del diagnóstico fue 37,5 años, con un retraso diagnóstico de 20 años. El 50% asociaba epilepsia, migraña, distonía o alteraciones neuropsiquiátricas. El 70% tenía una historia familiar de síntomas asociados a CACNA1A. Dos pacientes heterocigotos consanguíneos tuvieron descendencia homocigota con mortalidad infantil por encefalopatía epiléptica de inicio precoz de tipo 42. Se detectaron cinco variantes diferentes de CACNA1A. El 80% mostró factores desencadenantes, y el estrés fue el más común. La frecuencia episódica más habitual fue semanal. Seis pacientes desarrollaron ataxia interepisódica, aunque sólo uno precisó apoyo en la marcha. El 50% de los pacientes con neuroimagen presentó atrofia cerebelosa. El 80% inició acetazolamida durante el seguimiento, con respuesta a dosis altas en el 75%. La nefrolitiasis fue el efecto adverso más frecuente. La 4-aminopiridina fue una alternativa eficaz. Conclusiones: La AE2 presenta una alta variabilidad fenotípica inter- e intrafamiliar. El fenotipo más frecuente fueron episodios de inestabilidad, de horas de duración, semanales, con estrés como desencadenante, ataxia persistente y nistagmo evocado por la mirada. La acetazolamida, aunque es eficaz, no está exenta de complicaciones. El retraso diagnóstico es muy frecuente.(AU)

Objectives: To describe a series of patients with episodic ataxia type 2 (EA2), attending to epidemiological, clinical, radiological, and therapeutic variables. Material and methods: Retrospective revision of patients with molecular diagnosis of EA2 (CACNA1A mutations), between 1988 and 2022. Information achieved from the database of our Movement Disorders clinic. A descriptive statistical analysis was made. Results: Ten patients from five families were analyzed (six women). Median age at diagnosis was 37.5 years-old, with a median diagnostic delay of 20 years. 70% reported familial history of CACNA1A associated symptoms, although 50% presented migraine, epilepsy, dystonia, or neuropsychiatric alterations. Two heterozygous consanguineous patients had homozygotic descendance with infant mortality due to early-onset epileptic encephalopathy type 42. Five pathogenic/probably pathogenic CACNA1A variants were detected. 80% of patients had episodic triggers, being stress the most common. Episodes had a weekly frequency before treatment initiation. Six patients developed chronic ataxia (one patient demand gait support). 50% of patients with neuroimaging presented cerebellar atrophy. Acetazolamide were initiated in 80%, and 75% of them showed improvement of episodic symptoms. Nephrolithiasis was the most frequent side effect. Conclusions: EA2 has a great intrafamilial and interfamilial phenotypic variability. The most frequent phenotype were weekly episodes of unsteadiness, several hours of length, stress as the main trigger, chronic ataxia and gaze-evoked nystagmus. Acetazolamide is effective, although complications are usual. Neurologist must be alert as diagnostic delay is constant.(AU)

Five years' experience of the clinical exome sequencing in a Spanish single center.

Nowadays, exome sequencing is a robust and cost-efficient genetic diagnostic tool already implemented in many clinical laboratories. Despite it has undoubtedly improved our diagnostic capacity and has allowed the discovery of many new Mendelian-disease genes, it only provides a molecular diagnosis in up to 25-30% of cases. Here, we comprehensively evaluate the results of a large sample set of 4974 clinical exomes performed in our laboratory over a period of 5 years, showing a global diagnostic rate of 24.62% (1391/4974). For the evaluation we establish different groups of diseases and demonstrate how the diagnostic rate is not only dependent on the analyzed group of diseases (43.12% in ophthalmological cases vs 16.61% in neurological cases) but on the specific disorder (47.49% in retinal dystrophies vs 24.02% in optic atrophy; 18.88% in neuropathies/paraparesias vs 11.43% in dementias). We also detail the most frequent mutated genes within each group of disorders and discuss, on our experience, further investigations and directions needed for the benefit of patients.

Biallelic variants in genes previously associated with dominant inheritance: CACNA1A, RET and SLC20A2.

A subset of families with co-dominant or recessive inheritance has been described in several genes previously associated with dominant inheritance. Those recessive families displayed similar, more severe, or even completely different phenotypes to their dominant counterparts. We report the first patients harboring homozygous disease-related variants in three genes that were previously associated with dominant inheritance: a loss-of-function variant in the CACNA1A gene and two missense variants in the RET and SLC20A2 genes, respectively. All patients presented with a more severe clinical phenotype than the corresponding typical dominant form. We suggest that co-dominant or recessive inheritance for these three genes could explain the phenotypic differences from those documented in their cognate dominant phenotypes. Our results reinforce that geneticists should be aware of the possible different forms of inheritance in genes when WES variant interpretation is performed. We also evidence the need to refine phenotypes and inheritance patterns associated with genes in order to avoid failures during WES analysis and thus, raising the WES diagnostic capacity in the benefit of patients.

Sanger sequencing is no longer always necessary based on a single-center validation of 1109 NGS variants in 825 clinical exomes.

Despite the improved accuracy of next-generation sequencing (NGS), it is widely accepted that variants need to be validated using Sanger sequencing before reporting. Validation of all NGS variants considerably increases the turnaround time and costs of clinical diagnosis. We comprehensively assessed this need in 1109 variants from 825 clinical exomes, the largest sample set to date assessed using Illumina chemistry reported. With a concordance of 100%, we conclude that Sanger sequencing can be very useful as an internal quality control, but not so much as a verification method for high-quality single-nucleotide and small insertion/deletions variants. Laboratories might validate and establish their own thresholds before discontinuing Sanger confirmation studies. We also expand and validate 23 copy number variations detected by exome sequencing in 20 samples, observing a concordance of 95.65% (22/23).

Heterozygous CAPN3 missense variants causing autosomal-dominant calpainopathy in seven unrelated families.

AIMS: Recessive variants in CAPN3 gene are the cause of the commonest form of autosomal recessive limb girdle muscle dystrophy. However, two distinct in-frame deletions in CAPN3 (NM_000070.3:c.643_663del21 and c.598_621del15) and more recently, Gly445Arg and Arg572Pro substitutions have been linked to autosomal dominant (AD) forms of calpainopathy. We report 21 affected individuals from seven unrelated families presenting with an autosomal dominant form of muscular dystrophy associated with five different heterozygous missense variants in CAPN. METHODS: We have used massively parallel gene sequencing (MPS) to determine the genetic basis of a dominant form of limb girdle muscular dystrophy in affected individuals from seven unrelated families. RESULTS: The c.700G> A, [p.(Gly234Arg)], c.1327T> C [p.(Ser443Pro], c.1333G> A [p.(Gly445Arg)], c.1661A> C [p.(Tyr554Ser)] and c.1706T> C [p.(Phe569Ser)] CAPN3 variants were identified. Affected individuals presented in young adulthood with progressive proximal and axial weakness, waddling walking and scapular winging or with isolated hyperCKaemia. Muscle imaging showed fatty replacement of paraspinal muscles, variable degrees of involvement of the gluteal muscles, and the posterior compartment of the thigh and minor changes at the mid-leg level. Muscle biopsies revealed mild myopathic changes. Western blot analysis revealed a clear reduction in calpain 3 in skeletal muscle relative to controls. Protein modelling of these variants on the predicted structure of calpain 3 revealed that all variants are located in proximity to the calmodulin-binding site and are predicted to interfere with proteolytic activation. CONCLUSIONS: We expand the genotypic spectrum of CAPN3-associated muscular dystrophy due to autosomal dominant missense variants.

Multiple myeloma patients in long-term complete response after autologous stem cell transplantation express a particular immune signature with potential prognostic implication.

The proportion of multiple myeloma patients in long-term complete response (LTCR-MM) for more than 6 years after autologous stem cell transplantation (ASCT) is small. To evaluate whether this LTCR is associated with a particular immune signature, peripheral blood samples from 13 LTCR-MM after ASCT and healthy blood donors (HBD) were analysed. Subpopulations of T-cells (naïve, effector, central memory and regulatory), B-cells (naïve, marginal zone-like, class-switched memory, transitional and plasmablasts) and NK-cells expressing inhibitory and activating receptors were quantified by multiparametric flow cytometry (MFC). Heavy/light chains (HLC) were quantified by nephelometry. The percentage of CD4+ T-cells was lower in patients, whereas an increment in the percentage of CD4+ and CD8+ effector memory T-cells was associated with the LTCR. Regulatory T-cells and NK-cells were similar in both groups but a particular redistribution of inhibitory and activating receptors in NK-cells were found in patients. Regarding B-cells, an increase in naïve cells and a corresponding reduction in marginal zone-like and class-switched memory B-cells was observed. The HLC values were normal. Our results suggest that LTCR-MM patients express a particular immune signature, which probably reflects a 'high quality' immune reconstitution that could exert a competent anti-tumor immunological surveillance along with a recovery of the humoral immunity.