Unraveling the genetic landscape of undiagnosed cerebellar ataxia in Brazilian patients.

INTRODUCTION: Hereditary ataxias (HAs) encompass a diverse and genetically intricate group of rare neurodegenerative disorders, presenting diagnostic challenges. Whole-exome sequencing (WES) has significantly improved diagnostic success. This study aimed to elucidate genetic causes of cerebellar ataxia within a diverse Brazilian cohort. METHODS: Biological samples were collected from individuals with sporadic or familial cerebellar ataxia, spanning various ages and phenotypes, excluding common SCAs and Friedreich ataxia. RFC1 biallelic AAGGG repeat expansion was screened in all patients. For AAGGG-negative cases, WES targeting 441 ataxia-related genes was performed, followed by ExpansionHunter analysis for repeat expansions, including the recently described GGC-ZFHX3. Variant classification adhered to ClinGen guidelines, yielding definitive or probable diagnoses. RESULTS: The study involved 76 diverse Brazilian families. 16 % received definitive diagnoses, and another 16 % received probable ones. RFC1-related ataxia was predominant, with two definitive cases, followed by KIF1A (one definitive and one probable) and SYNE-1 (two probable). Early-onset cases exhibited higher diagnostic rates. ExpansionHunter improved diagnosis by 4 %.We did not detected GGC-ZFHX3 repeat expansion in this cohort. CONCLUSION: This study highlights diagnostic complexities in cerebellar ataxia, even with advanced genetic methods. RFC1, KIF1A, and SYNE1 emerged as prevalent mutations. ZFHX3 repeat expansion seem to be rare in Brazilian population. Early-onset cases showed higher diagnostic success. WES coupled with ExpansionHunter holds promise as a primary diagnostic tool, emphasizing the need for broader NGS accessibility in Brazil.

Multiple copy number variation in a patient with Kleefstra syndrome / Múltiplas variações de número de cópias em paciente com síndrome de Kleefstra

ABSTRACT Objective: To report a rare case of a patient with a molecular diagnosis of Kleefstra syndrome (KS) who has four other chromosomal alterations involving pathogenic variants. Case description: Male patient, two years old, with global delay, including in neuropsychomotor development, ocular hypertelorism, broad forehead, brachycephaly, hypotonia, ligament laxity, unilateral single palmar crease and arachnoid cyst. The microarray-based comparative genomic hybridization (a-CGH) identified copy number variations (CNVs) in five regions: 9q34.3, 6p22.1, Yq11.223, Yp11.23, and 2q24.1. The heterozygous microdeletion in 9q34.3 involving the EHMT1 gene confirms the diagnosis of KS. Comments: The presence of pathogenic CNVs and/or those of uncertain significance, located on chromosomes 2, 6 and Y, may be contributing to a variability in the patient's clinical condition (arachnoid cyst, single palmar fold and ligament laxity), compared to other individuals with only KS genetic alteration, making the dignosis of the disease harder.

RESUMO Objetivo: Relatar um caso raro de paciente com diagnóstico molecular de síndrome de Kleefstra (SK) que apresenta quatro outras alterações cromossômicas envolvendo variantes patogênicas. Descrição do caso: Paciente masculino, dois anos de idade, com atraso global de desenvolvimento neuropsicomotor, hipertelorismo ocular, fronte ampla, braquicefalia, hipotonia, frouxidão ligamentar, prega palmar única unilateral e cisto aracnoide. Exame de hibridização genômica comparativa (a-CGH) identificou variações de número de cópias (CNV) em cinco regiões: 9q34.3, 6p22.1, Yq11.223, Yp11.23 e 2q24.1. A microdeleção heterozigótica em 9q34.3 confirma o diagnóstico de síndrome de Kleefstra. Comentários: A presença das CNV patogênicas e/ou de significado incerto, localizadas nos cromossomos 2, 6 e Y, pode estar contribuindo para uma variabilidade no quadro clínico do paciente (cisto aracnoide, prega palmar única e frouxidão ligamentar) em relação a outros indivíduos somente com alteração genética da SK, dificultando o diagnóstico da doença.

Phenocopy in a patient with triple negative breast cancer: a case report.

A total of 1.67 million breast cancer cases per year are reported worldwide. Of these, 5%-10% are caused by inherited mutations. Phenocopy is a rare phenomenon, with only a few cases reported in the literature. In phenocopies, phenotypes identical to those with genetic origin occur because of environmental factors rather than familial mutations. We describe a case of phenocopy in a 44-year-old female patient with triple-negative breast cancer. The mother and sister wee heterozygous for c.1813delA, p.Ile605TyrfsTer9 in BRCA2 . The patient underwent genetic testing for BRCA1 and BRCA2 and exome sequencing. Familial or other cancer variants were not detected. The most accepted phenocopy theory is that patients without genetic variants but who are carriers of these mutations undergo cellular changes due to environmental factors, increasing the risk of breast cancer. Therefore, the detection of phenocopy in patients with breast cancer is important in clinical practice.

Multiple copy number variation in a patient with Kleefstra syndrome.

OBJECTIVE: To report a rare case of a patient with a molecular diagnosis of Kleefstra syndrome (KS) who has four other chromosomal alterations involving pathogenic variants. CASE DESCRIPTION: Male patient, two years old, with global delay, including in neuropsychomotor development, ocular hypertelorism, broad forehead, brachycephaly, hypotonia, ligament laxity, unilateral single palmar crease and arachnoid cyst. The microarray-based comparative genomic hybridization (a-CGH) identified copy number variations (CNVs) in five regions: 9q34.3, 6p22.1, Yq11.223, Yp11.23, and 2q24.1. The heterozygous microdeletion in 9q34.3 involving the EHMT1 gene confirms the diagnosis of KS. COMMENTS: The presence of pathogenic CNVs and/or those of uncertain significance, located on chromosomes 2, 6 and Y, may be contributing to a variability in the patient's clinical condition (arachnoid cyst, single palmar fold and ligament laxity), compared to other individuals with only KS genetic alteration, making the dignosis of the disease harder.

Frequency of GAA-FGF14 Ataxia in a Large Cohort of Brazilian Patients With Unsolved Adult-Onset Cerebellar Ataxia.

Objectives: Intronic FGF14 GAA repeat expansions have recently been found to be a common cause of hereditary ataxia (GAA-FGF14 ataxia; SCA27B). The global epidemiology and regional prevalence of this newly reported disorder remain to be established. In this study, we investigated the frequency of GAA-FGF14 ataxia in a large cohort of Brazilian patients with unsolved adult-onset ataxia. Methods: We recruited 93 index patients with genetically unsolved adult-onset ataxia despite extensive genetic investigation and genotyped the FGF14 repeat locus. Patients were recruited across 4 different regions of Brazil. Results: Of the 93 index patients, 8 (9%) carried an FGF14 (GAA)≥250 expansion. The expansion was also identified in 1 affected relative. Seven patients were of European descent, 1 was of African descent, and 1was of admixed American ancestry. One patient carrying a (GAA)376 expansion developed ataxia at age 28 years, confirming that GAA-FGF14 ataxia can occur before the age of 30 years. One patient displayed episodic symptoms, while none had downbeat nystagmus. Cerebellar atrophy was observed on brain MRI in 7 of 8 patients (87%). Discussion: Our results suggest that GAA-FGF14 ataxia is a common cause of adult-onset ataxia in the Brazilian population, although larger studies are needed to fully define its epidemiology.

A Brazilian case of IFAP syndrome with severe congenital ichthyosis and limb malformations caused by a rare variant in MBTPS2.

OBJECTIVE: The classic triad, which defines IFAP syndrome, is ichthyosis follicularis, alopecia, and photophobia. It is a rare X-linked genetic disorder characterized by multiple congenital anomalies with variable severity, caused by pathogenic variants in the MBTPS2 gene, which encodes a zinc metalloprotease that is essential for normal development. This study aimed to report a case of a Brazilian patient with IFAP syndrome presenting skeletal anomalies, which is a rare finding among patients from different families. CASE DESCRIPTION: We describe a male proband with IFAP syndrome showing severe ichthyosis congenita, cryptorchidism, limb malformation, and comprising the BRESHECK syndrome features. Using whole-exome sequencing, we identified a rare missense variant in hemizygosity in the MBTPS2 gene, which had not been identified in other family members. COMMENTS: This is the first diagnosis of IFAP syndrome in Brazil with a molecular investigation. The present case study thus expands our knowledge on the mutational spectrum of MBPTS2 associated with IFAP syndrome.

Autism and duplication of 17q12q21.2 by array-CGH: a case report.

OBJECTIVE: Autism spectrum disorder (ASD) affects cognitive development and social interaction on different levels. Genetic and environmental factors are associated with secondary ASD. Genetic inheritance is mainly polygenic, and 10% are copy number variations (CNVs). Array comparative genomic hybridization (array-CGH) is used to identify CNVs. This report aimed to discuss autism spectrum disorder and its diagnosis by array comparative genomic hybridization, highlighting the association with the pathogenic duplication of 17q12q21.2. CASE DESCRIPTION: A male baby was born at 37 weeks' gestation by cesarean section. The child showed strabismus, cryptorchidism, hypertelorism, frontal bossing, and developmental delay, walking at 25 months and talking at 4 years. At the age of 2 years, array-CGH of peripheral blood revealed a 5.6-Mb 17q12q21.2 duplication or arr 17q12q21.2 (34,815,527-40,213.109)x3 encompassing 190 genes, including HNF-1B and LHX1. The child was clinically diagnosed with ASD. COMMENTS: Changes in the 17q12 segment, such as the duplication found, have been associated with the development of several problems in previous studies, mainly kidney diseases and behavioral disorders. Located at this chromosome region, HNF1's homeobox B codes a member of the superfamily containing homeodomain of transcription factors. Another gene associated with abnormalities in neurological development regarding 17q12 deletions is LHX1, as shown in this case study. LHX1 plays a role in the migration and differentiation of GABA neurons, modulating the survival of pre-optical interneurons, thus affecting cellular migration and distribution in the cortex. Changes in this control result in flaws in interneuron development, contributing to the pathophysiology of psychiatric diseases.

Autism and duplication of 17q12q21.2 by array-CGH: a case report / Autismo e duplicação da região 17q12q21.2 com array-CGH: um relato de caso

ABSTRACT Objective: Autism spectrum disorder (ASD) affects cognitive development and social interaction on different levels. Genetic and environmental factors are associated with secondary ASD. Genetic inheritance is mainly polygenic, and 10% are copy number variations (CNVs). Array comparative genomic hybridization (array-CGH) is used to identify CNVs. This report aimed to discuss autism spectrum disorder and its diagnosis by array comparative genomic hybridization, highlighting the association with the pathogenic duplication of 17q12q21.2. Case description: A male baby was born at 37 weeks' gestation by cesarean section. The child showed strabismus, cryptorchidism, hypertelorism, frontal bossing, and developmental delay, walking at 25 months and talking at 4 years. At the age of 2 years, array-CGH of peripheral blood revealed a 5.6-Mb 17q12q21.2 duplication or arr 17q12q21.2 (34,815,527-40,213.109)x3 encompassing 190 genes, including HNF-1B and LHX1. The child was clinically diagnosed with ASD. Comments: Changes in the 17q12 segment, such as the duplication found, have been associated with the development of several problems in previous studies, mainly kidney diseases and behavioral disorders. Located at this chromosome region, HNF1's homeobox B codes a member of the superfamily containing homeodomain of transcription factors. Another gene associated with abnormalities in neurological development regarding 17q12 deletions is LHX1, as shown in this case study. LHX1 plays a role in the migration and differentiation of GABA neurons, modulating the survival of pre-optical interneurons, thus affecting cellular migration and distribution in the cortex. Changes in this control result in flaws in interneuron development, contributing to the pathophysiology of psychiatric diseases.

RESUMO Objetivo: O transtorno do espectro autista (TEA) afeta o desenvolvimento cognitivo e a interação social em diferentes níveis. Fatores genéticos e ambientais estão associados a TEA secundário. A herança genética é principalmente poligênica e, em 10%, são variações do número de cópias (CNV). A hibridização genômica comparativa de array (array-CGH) é usada para identificar CNV. Este relato objetivou discutir o TEA e seu diagnóstico por array-CGH, destacando a associação com a duplicação patogênica do 17q12q21.2. Descrição do caso: Um bebê do sexo masculino nasceu com 37 semanas de gestação por cesariana. A criança apresentou atraso no desenvolvimento, andando aos dois anos e um mês e falando aos quatro, exibindo estrabismo, criptorquidia, hipertelorismo e saliência frontal. Aos dois anos, o array-CGH de sangue periférico revelou duplicação de 5,6 Mb 17q12q21.2 ou arr 17q12q21.2 (34.815.527-40.213.109) x3 abrangendo 190 genes, incluindo HNF1B e LHX1. A criança foi clinicamente diagnosticada com TEA. Comentários: Alterações no segmento 17q12, como a duplicação encontrada, têm sido associadas ao desenvolvimento de patologias renais e distúrbios comportamentais. Localizado nessa região cromossômica, o HNF1B codifica um membro da superfamília que contém o domínio dos fatores de transcrição. Outro gene foi associado a anormalidades neurológicas, em relação às deleções 17q12, o LHX1, como mostrado neste caso. O LHX1 desempenha um papel na migração e diferenciação dos neurônios GABA, modulando a sobrevivência dos interneurônios pré-ópticos e afetando, assim, a migração e distribuição celular no córtex. Mudanças nesse controle resultam em falhas no desenvolvimento dos interneurônios, contribuindo para a fisiopatologia das doenças psiquiátricas.

A Brazilian case of IFAP syndrome with severe congenital ichthyosis and limb malformations caused by a rare variant in MBTPS2 / Um caso brasileiro de síndrome IFAP com ictiose congênita grave e malformações de membros causadas por uma variante rara em MBTPS2

Abstract Objective: The classic triad, which defines IFAP syndrome, is ichthyosis follicularis, alopecia, and photophobia. It is a rare X-linked genetic disorder characterized by multiple congenital anomalies with variable severity, caused by pathogenic variants in the MBTPS2 gene, which encodes a zinc metalloprotease that is essential for normal development. This study aimed to report a case of a Brazilian patient with IFAP syndrome presenting skeletal anomalies, which is a rare finding among patients from different families. Case description: We describe a male proband with IFAP syndrome showing severe ichthyosis congenita, cryptorchidism, limb malformation, and comprising the BRESHECK syndrome features. Using whole-exome sequencing, we identified a rare missense variant in hemizygosity in the MBTPS2 gene, which had not been identified in other family members. Comments: This is the first diagnosis of IFAP syndrome in Brazil with a molecular investigation. The present case study thus expands our knowledge on the mutational spectrum of MBPTS2 associated with IFAP syndrome.

RESUMO Objetivo: A clássica tríade de ictiose folicular, alopecia e fotofobia dá nome a uma síndrome rara de origem genética com herança ligada ao cromossomo X (síndrome IFAP, do inglês Ichthyosis Follicularis, Alopecia, and Photophobia). Esta é uma síndrome caracterizada por múltiplas anomalias congênitas de expressividade variável, causada por variantes patogênicas no gene MBTPS2, que codifica uma zinco-metaloprotease essencial para o desenvolvimento normal humano. O objetivo deste estudo é apresentar o relato de caso de um paciente brasileiro com síndrome IFAP que apresentou anomalias esqueléticas, um achado raro entre os pacientes de diferentes famílias. Descrição do caso: Apresentamos um probando do sexo masculino com síndrome IFAP, com ictiose congênita grave, criptorquidia, malformação de membros e as características da síndrome de BRESHECK. Por meio do sequenciamento do exoma completo, identificamos uma variante rara do tipo missense, em hemizigose, no gene MBTPS2, não identificada em outros membros da família. Comentários: Este é o primeiro diagnóstico de síndrome IFAP no Brasil com investigação molecular. A análise molecular e a descrição de uma variante rara no gene MBPTS2 expandem nosso conhecimento sobre o espectro mutacional desse gene associado à síndrome IFAP.

Phenocopy in a patient with triple negative breast cancer: a case report

ABSTRACT A total of 1.67 million breast cancer cases per year are reported worldwide. Of these, 5%-10% are caused by inherited mutations. Phenocopy is a rare phenomenon, with only a few cases reported in the literature. In phenocopies, phenotypes identical to those with genetic origin occur because of environmental factors rather than familial mutations. We describe a case of phenocopy in a 44-year-old female patient with triple-negative breast cancer. The mother and sister wee heterozygous for c.1813delA, p.Ile605TyrfsTer9 in BRCA2 . The patient underwent genetic testing for BRCA1 and BRCA2 and exome sequencing. Familial or other cancer variants were not detected. The most accepted phenocopy theory is that patients without genetic variants but who are carriers of these mutations undergo cellular changes due to environmental factors, increasing the risk of breast cancer. Therefore, the detection of phenocopy in patients with breast cancer is important in clinical practice.

Genetics of COVID-19

Abstract Objective This narrative, non-systematic review provides an update on the genetic aspects of the SARS-CoV-2 virus and its interactions with the human genome within the context of COVID-19. Although the main focus is on the etiology of this new disease, the genetics of SARS-CoV-2 impacts prevention, diagnosis, prognosis, and the development of therapies. Data source A literature search was conducted on MEDLINE, BioRxiv, and SciELO, as well as a manual search on the internet (mainly in 2019 and 2020) using the keywords "COVID-19," "SARS-CoV-2," "coronavirus," "genetics," "molecular," "mutation," "vaccine," "Brazil," "Brasil," and combinations of these terms. The keywords "Brazil" and "Brasil" were used to find publications that were specific to the Brazilian population's molecular epidemiology data. Articles most relevant to the scope were selected non-systematically. Data synthesis A number of publications illustrate an expanding knowledge on the genetics and genomics of SARS-CoV-2 and its implications for understanding COVID-19. Conclusions Knowledge of the SARS-CoV-2 genome sequence permits an in-depth investigation of the role its proteins play in the pathophysiology of COVID-19, which in turn will be enormously valuable for understanding the evolutionary, clinical, and epidemiological aspects of this disease and focusing on prevention and treatment.

Imunizações em pacientes com doenças raras ­ Posicionamento conjunto da Sociedade Brasileira de Imunizações (SBIm), Associação Brasileira de Alergia e Imunologia (ASBAI) e Sociedade Brasileira de Pediatria (SBP) / Immunizations in patients with rare diseases ­ A joint position statement of the Brazilian Society of Immunizations (SBIm), Brazilian Association of Allergy and Immunology (ASBAI), and Brazilian Society of Pediatrics (SBP)

Introdução: De acordo com a Organização Mundial da Saúde, a prevalência de doenças raras (abaixo de 65 casos/100.000 habitantes) é de 6%, e variável na dependência da população em estudo. Há 6.172 doenças raras (DR) catalogadas. Esquemas vacinais específicos para DR não estão disponíveis no Brasil, e esta orientação é limitada na maioria dos países. Objetivos: Identificar e propor esquemas específicos de imunização para pacientes com DR, tendo-se em conta segurança e eficácia. Fonte de dados: Revisão não sistemática da literatura, com busca de artigos de 2000 a 2020 no PubMed, Google Scholar, SciELO e Orphanet usando os termos "rare diseases" ou "inborn errors of metabolism" ou "cystic fibrosis" ou "inborn errors of immunity" e "vaccines" ou "immunization" ou "vaccination", nos idiomas inglês, francês, espanhol e português. Conclusões: A imunização de pessoas com DR é tema complexo, com poucas recomendações publicadas a este respeito, e na maioria das vezes realizada de modo empírico. É importante que a equipe médica que acompanha esses pacientes tenha um olhar abrangente e proporcione a prevenção mais completa possível.

Background: According to the World Health Organization, the prevalence of rare diseases (below 65 cases/100 000 population) is 6% and may vary depending on the study population. There are 6172 rare diseases (RD) listed. RD-specific vaccine schemes are not available in Brazil, and guidance is limited in most countries. Objectives: To identify and propose specific immunization schemes for RD patients, valuing safety and efficacy. Data source: A nonsystematic literature review was conducted, with search for articles from 2000 to 2020 on PubMed, Google Scholar, SciELO, and Orphanet with the terms "rare diseases" or "inborn errors of metabolism" or "cystic fibrosis" or "inborn errors of immunity" and "vaccines" or "immunization" or "vaccination," in English, French, Spanish, and Portuguese languages. Conclusions: Immunization of RD patients is a complex topic with few published recommendations, most often produced empirically. The medical teams following up these patients should have a more comprehensive insight and provide the most complete prevention possible.

Genetics of COVID-19.

OBJECTIVE: This narrative, non-systematic review provides an update on the genetic aspects of the SARS-CoV-2 virus and its interactions with the human genome within the context of COVID-19. Although the main focus is on the etiology of this new disease, the genetics of SARS-CoV-2 impacts prevention, diagnosis, prognosis, and the development of therapies. DATA SOURCE: A literature search was conducted on MEDLINE, BioRxiv, and SciELO, as well as a manual search on the internet (mainly in 2019 and 2020) using the keywords "COVID-19," "SARS-CoV-2," "coronavirus," "genetics," "molecular," "mutation," "vaccine," "Brazil," "Brasil," and combinations of these terms. The keywords "Brazil" and "Brasil" were used to find publications that were specific to the Brazilian population's molecular epidemiology data. Articles most relevant to the scope were selected non-systematically. DATA SYNTHESIS: A number of publications illustrate an expanding knowledge on the genetics and genomics of SARS-CoV-2 and its implications for understanding COVID-19. CONCLUSIONS: Knowledge of the SARS-CoV-2 genome sequence permits an in-depth investigation of the role its proteins play in the pathophysiology of COVID-19, which in turn will be enormously valuable for understanding the evolutionary, clinical, and epidemiological aspects of this disease and focusing on prevention and treatment.

Balance and physical functioning in Spinocerebellar ataxias 3 and 10.

OBJECTIVES: Limitations of functional capacity and balance are common features of the natural history of spinocerebellar ataxias (SCA). However, their onset and progression patterns differ according to subtype. The aim of our study was to compare physical functionality and balance parameters in SCA10 and SCA3 patients, correlating with clinical variables. MATERIALS & METHODS: Cross-sectional study evaluating ninety-five SCA patients (60 with SCA3 and 35 with SCA10) with validated scales for functional independence, balance and the severity of signs and symptoms. RESULTS: The groups were similar in terms of age and gender, and results were adjusted for age at symptom onset. The SCA10 patients had better results for balance and functional independence (p < 0.007). They also had lower scores for disease severity (p < 0.0002) and the subitems gait (p < 0.0005), posture (p < 0.0021) and sitting balance (p < 0.0008). Symptom progression in both groups was similar for patients with a disease duration of up to ten years, but there was a more marked decline in SCA3 patients after this period. CONCLUSIONS: We have shown that disease progression as assessed by balance and physical functioning is slower in SCA10 patients than SCA3 patients, particularly after 10 years of disease. These findings are important as they can help to characterize the disease, assisting in the development of new therapies and rehabilitation programs.

Is Ataxia an Underestimated Symptom of Huntington's Disease?

Background: Huntington's disease (HD) is a progressive disorder characterized by motor, cognitive and psychiatric features. Cerebellar ataxia is classically considered as uncommon in HD clinical spectrum. Objective: To determine the prevalence of cerebellar ataxia in patients with HD, both in the early and in the late stages of HD. Methods: Seventy-two individuals considered eligible were assessed by two trained doctors, applying the Scale for Assessment and Rating of Ataxia (SARA) and Brief Ataxia Rating Scale (BARS) for ataxia, the Unified Huntington's Disease Rating Scale (UHDRS) and also, Barthel Index (BI), in order to evaluate functional capacity. Results: Fifty-one patients (70.8%) presented with clinical ataxia at the time of examination (mean time of disease was 9.1 years). Six (8.33%) patients presented with cerebellar ataxia as first symptom. When stratified according to time of disease, a decline in the presence of chorea (p = 0.032) and an increase in cognitive deficit (p = 0.023) were observed in the patients as the disease progressed. The presence of ataxia was associated with longer duration of illness and severity of illness (UHDRS) (p < 0.0001), and shorter Barthel (less functionality) (p = 0.001). Conclusions: Cerebellar involvement may play an important role in natural history of brain degeneration in HD. The presence of cerebellar ataxia in HD is relevant and it may occur even in early stages, and should be included as part of the motor features of the disease.