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- Missense Variant in TTBK2 Kinase Domain Causes Loss of Function and Impaired Protein Phosphorylation.Publication . Felício, Daniela; Osório, Hugo; Pereira, Conceição; Brandão, Ana Filipa; Freixo, João Parente; Carvalho, Inês; Sousa, Ana Paula; Castro-Caldas, Margarida; Sequeiros, Jorge; Lemos, Carolina; Santos, MarianaTau tubulin kinase 2 (TTBK2) is a ubiquitous serine-threonine protein kinase implicated in diverse cellular processes, including microtubule regulation, ciliogenesis, synaptic signaling, and the phosphorylation of key proteins like TDP-43. Despite its relevance, many aspects of TTBK2 function in both physiological and pathological conditions remain poorly understood. Truncating variants in TTBK2 gene cause spinocerebellar ataxia type 11 (SCA11), a rare form of autosomal dominant cerebellar ataxia. However, the functional consequences and pathogenic potential of missense variants have yet to be elucidated. In this study, we developed a CRISPR/Cas9 knock-in cell model harboring a missense variant in TTBK2 kinase domain (NM_173500.4:c.625 C > T; p.Leu209Phe) to evaluate its impact on TTBK2 expression, associated protein levels, and phosphoproteomic profiles. TTBK2 missense variant (TTBK2-L209F) was associated with reduced TTBK2 protein levels, altered levels of cytoskeleton-related proteins, and impaired kinase activity, namely toward TDP-43. Phosphoproteomic analyses identified dysregulation in pathways linked to gene regulation, protein degradation, cytoskeletal organization, and TGF-β signaling. These findings provide valuable insights into the biological roles of TTBK2 in cellular signaling. Moreover, this study underscores the importance of functional studies to better understand the consequences of TTBK2 missense variants, particularly those affecting the kinase domain, and their potential contribution to disease.
- A Complex Case of Koolen-De Vries Syndrome Associated with Hypopituitarism and Type 1 Diabetes Mellitus.Publication . Félix Cabral, Mafalda; Branco Caetano, Francisco; Conceição, Carla; Oliveira Antunes, Diana; Lopes, LurdesComplex diseases arise from the interplay of genetic and environmental factors. We present a case where complex diseases seem to coexist. A 12-month-old girl was referred for short stature and hypotonia. Initial evaluation revealed central hypothyroidism, growth hormone deficiency and a small pituitary gland with ectopic neurohypophysis. Replacement therapy improved growth, but developmental delay and strabismus ensued. At age 10, she experienced a first seizure treated with levetiracetam. At age 12, she presented diabetic ketoacidosis and functional insulin therapy was started; positive autoantibodies confirmed autoimmune etiology. Initial genetic testing performed by microarray analysis retrieved normal results, but exome sequencing revealed a heterozygous pathogenic variant in KANSL1 gene, allowing for the diagnosis of Koolen-de Vries syndrome. In this patient, Koolen-de Vries syndrome presented initially as hypopituitarism and only later epilepsy. Afterwards, type 1 diabetes mellitus ensued, highlighting the complexity of intertwined conditions.
- Medically Actionable Secondary Findings from Whole-Exome Sequencing (WES) Data in a Sample of 3972 Individuals.Publication . Melo, Mafalda; Ribeiro, Mariana; Silva, Paulo Filipe; Valente, Susana; Alves, Filipe; Venâncio, Margarida; Sequeiros, Jorge; Freixo, João Parente; Antunes, Diana; Oliveira, JorgeThe application of whole-exome sequencing (WES) for diagnostic purposes has the potential to unravel secondary findings unrelated with the primary reason of testing. Some of those might be of high clinical utility and comprise disease-causing variants in genes, related to life-threatening and clinically actionable diseases. Clarifying the allelic frequencies of such variants in specific populations is a crucial step for the large-scale deployment of genomic medicine. We analysed medically relevant variants in the 81 genes from the American College of Medical Genetics and Genomics (ACMG) v3.2 list of actionable loci, using WES data from a diagnostic laboratory cohort of 3972 persons, tentatively resampled to represent the Portuguese population geographic distribution. We identified medically actionable variants in 6.2% of our cohort, distributed across several disease domains: cardiovascular disorders (3.0%), cancer predisposition (2.0%), miscellaneous disorders (1.1%), and metabolic disorders (0.1%). Additionally, we estimated a frequency of heterozygotes for recessive disease alleles of 11.1%. Overall, our results suggest that medically actionable findings can be identified in approximately 6.2% of persons from our population. This is the first study estimating medically actionable findings in Portugal. These results provide valuable insight for patients, healthcare providers, and policymakers involved in advancing genomic medicine at the national and international level.
- Multidisciplinary Outpatient Clinic of Neurocutaneous Diseases: Five-year Experience of a Pediatric Tertiary Hospital in Portugal.Publication . Rebelo, Mafalda; Francisco, Telma; Perry da Câmara, Rosário; Pereira, Andreia; Iraneta, Amets; Amorim, Marta; Paiva Lopes, Maria João; Lopes da Silva, Rita; Cordeiro, Ana IsabelIntroduction: Neurocutaneous syndromes (NCS) are a heterogeneous group of conditions with multiorgan involvement and diverse manifestations, evolving throughout life with significant morbidity. A multidisciplinary approach to NCS patients has been advocated, although a specific model is not yet established. The aim of this study was 1) to describe the organization of the recently created Multidisciplinary Outpatient Clinic of Neurocutaneous Diseases (MOCND) at a Portuguese pediatric tertiary hospital; 2) to share our institutional experience focusing on the most common conditions, neurofibromatosis type 1 (NF1) and tuberous sclerosis complex (TSC); 3) to analyze the advantages of a multidisciplinary center and approach in NCS. Methods: Retrospective analysis of 281 patients enrolled in the MOCND over the first five years of activity (October 2016 to December 2021), reviewing genetics, family history, clinical features, complications, and therapeutic strategies for NF1 and TSC. Results: The clinic works weekly with a core team of pediatricians and pediatric neurologists supported by other specialties as needed. Of the 281 patients enrolled, 224 (79.7%) had identifiable syndromes such as NF1 (n = 105), TSC (n = 35), hypomelanosis of Ito (n = 11), Sturge-Weber syndrome (n = 5), and others. In NF1 patients, 41.0% had a positive family history, all manifested café-au-lait macules, 38.1% neurofibromas with 45.0% being large plexiform neurofibromas. Sixteen were under treatment with selumetinib. Genetic testing was performed in 82.9% of TSC patients with pathogenic variants found in TSC2 gene in 72.4% patients (82.7% if considered contiguous gene syndrome). Family history was positive in 31.4%. All TSC patients presented hypomelanotic macules and fulfilled diagnostic criteria. Fourteen patients were being treated with mTOR inhibitors. Conclusion: Offering a systematic and multidisciplinary approach to NCS patients enables timely diagnosis, promotes a structured follow-up, and encourages discussion to outline management plans for optimal care to every patient, with significant impact on the quality of life of patients and families.
- Pachydysostosis of the Fibula in a Case of Familial Adenomatous Polyposis.Publication . Oliveira, Daniela; Maia, Sofia; Balacó, Inês; Coelho, Paulo; Almeida, Susana; Venâncio, Margarida; Saraiva, Jorge; Nishimura, Gen; Sousa, Sérgio BBackground: Familial Adenomatous Polyposis (FAP) is a colorectal cancer (CRC) predisposition syndrome caused by germline APC mutations and characterised by an increased risk of CRC and colonic polyps and, in certain forms, of specific prominent extraintestinal manifestations, namely osteomas, soft tissue tumours and dental anomalies. Pachydysostosis of the fibula is a rare clinical entity defined by unilateral bowing of the distal portion of the fibula and elongation of the entire bone, without affectation of the tibia. Clinical report: We report a 17-year-old male, who presented with a non-progressive bowing of the right leg detected at 18 months of age caused by a fibula malformation (later characterized as pachydysostosis) and a large exophytic osteoma of the left radius, noticed at the age of 15 years, without gastrointestinal symptoms. There was no relevant family history. Detailed characterisation revealed multiple osteomas, skin lesions and dental abnormalities, raising the hypothesis of FAP. This diagnosis was confirmed by genetic testing [c.4406_4409dup p.(Ala1471Serfs*17) de novo mutation in the APC gene] and endoscopic investigation (multiple adenomas throughout the colon, ileum and stomach). Discussion: This case report draws attention to the phenotypic spectrum of skeletal manifestations of FAP: this patient has a congenital fibula malformation, not previously associated with this syndrome, but which is likely to have been its first manifestation in this patient. This clinical case also illustrates the challenges in the early diagnosis of FAP, especially without family history, and highlights the importance of a multidisciplinary approach and the adequate study of rare skeletal abnormalities.
- Multidisciplinary Outpatient Clinic of Neurocutaneous Diseases: Five-Year Experience of a Pediatric Tertiary Hospital in PortugalPublication . Rebelo, M; Francisco, T; Perry da Câmara, R; Pereira, A; Iraneta, A; Amorim, M; Paiva Lopes, MJ; Lopes da Silva, R; Cordeiro, AIIntroduction: Neurocutaneous syndromes (NCS) are a heterogeneous group of conditions with multiorgan involvement and diverse manifestations, evolving throughout life with significant morbidity. A multidisciplinary approach to NCS patients has been advocated, although a specific model is not yet established. The aim of this study was 1) to describe the organization of the recently created Multidisciplinary Outpatient Clinic of Neurocutaneous Diseases (MOCND) at a Portuguese pediatric tertiary hospital; 2) to share our institutional experience focusing on the most common conditions, neurofibromatosis type 1 (NF1) and tuberous sclerosis complex (TSC); 3) to analyze the advantages of a multidisciplinary center and approach in NCS. Methods: Retrospective analysis of 281 patients enrolled in the MOCND over the first five years of activity (October 2016 to December 2021), reviewing genetics, family history, clinical features, complications, and therapeutic strategies for NF1 and TSC. Results: The clinic works weekly with a core team of pediatricians and pediatric neurologists supported by other specialties as needed. Of the 281 patients enrolled, 224 (79.7%) had identifiable syndromes such as NF1 (n = 105), TSC (n = 35), hypomelanosis of Ito (n = 11), Sturge-Weber syndrome (n = 5), and others. In NF1 patients, 41.0% had a positive family history, all manifested café-au-lait macules, 38.1% neurofibromas with 45.0% being large plexiform neurofibromas. Sixteen were under treatment with selumetinib. Genetic testing was performed in 82.9% of TSC patients with pathogenic variants found in TSC2 gene in 72.4% patients (82.7% if considered contiguous gene syndrome). Family history was positive in 31.4%. All TSC patients presented hypomelanotic macules and fulfilled diagnostic criteria. Fourteen patients were being treated with mTOR inhibitors. Conclusion: Offering a systematic and multidisciplinary approach to NCS patients enables timely diagnosis, promotes a structured follow-up, and encourages discussion to outline management plans for optimal care to every patient, with significant impact on the quality of life of patients and families.
- TANGO2 Deficiency Disorder: Two Cases of Developmental Delay Preceding Metabolic CrisisPublication . Dias, JV; Carvalho, AA; Freixo, JP; Antunes, D; Martins, AA; Painho, T; Jacinto, SBackground: TANGO2 deficiency disorder is a rare genetic disease caused by biallelic defects in TANGO2 gene. Methods: We report the clinical phenotype of two children with TANGO2 deficiency disorder. Results: Patient 1 is a female child presenting with developmental delay and microcephaly during the second year of life, who evolved with severe cognitive impairment, facial dysmorphisms, spastic paraparesis, and atonic seizures. At age 13 years, she was hospitalized due to an episode of rhabdomyolysis complicated with cardiac arrhythmia and hypothyroidism. Patient 2 is a female child with dysmorphic facial features, cleft palate, and developmental delay who was diagnosed with DiGeorge syndrome. At age three years, she presented with an acute episode of severe rhabdomyolysis in the context of human herpesvirus 6 infection. After the resolution of this acute episode, she maintained recurrent muscle weakness with axial hypotonia and progressive spasticity of the lower extremities. In both patients, diagnosis of TANGO2 deficiency disorder was only confirmed after an acute metabolic crisis. Conclusions: A high index of suspicion for TANGO2 deficiency disorder is needed in patients with developmental delay or other neurological symptoms and episodic rhabdomyolysis.
- Perfil Genético da Surdez: Reabilitação Auditiva e Fatores Preditivos de PrognósticoPublication . Pereira, S; Nunes, S; Mariano, M; Sousa, H; Lavra, T; Kay, T; Barros, EObjetivos: Caracterizar a população com surdez de etiologia genética, a relação genótipo-fenótipo e fatores prognósticos na decisão de tratamento de reabilitação. Material e Métodos: Análise retrospetiva da população pediátrica referenciada da consulta de Reabilitação Auditiva à consulta de Genética Médica entre janeiro-2012 e dezembro-2017. Resultados: Foram encaminhadas 128 crianças e o estudo genético foi positivo em 47%. Os resultados foram sugestivos de haver correlação genótipo-fenótipo nas mutações do gene GJB2 (p=0,30), tendo este grupo etiológico sido o que obteve os melhores ganhos auditivos (p=0,57) e linguísticos (p=0,19) com a reabilitação. O estudo genético revelou alterações associadas a hipoacusia progressiva em seis doentes e identificou variantes que afetam o órgão de Corti, prevendo o desempenho com implante coclear (IC). Conclusões: A confirmação etiológica permite prever a evolução da hipoacusia, como observado no gene GJB2. Doentes com mutações nos genes expressos no labirinto membranoso, com preservação do gânglio espiral, apresentam bom prognóstico com IC.
- Caracterização de Crianças com Distúrbio do Espectro da Neuropatia Auditiva e sua ReabilitaçãoPublication . Mariano, M; Correia, I; Nunes, S; Cunha, I; Sousa, H; Kay, T; Barros, EObjectivos: Identificar e caracterizar os casos pediátricos de Distúrbio do Espectro da Neuropatia Auditiva (DENA) e analisar a sua reabilitação. Desenho do Estudo: Estudo observacional descritivo. Material e Métodos: Análise dos processos clínicos de 671 doentes avaliados em primeira consulta de reabilitação auditiva pediátrica entre 2012 e 2019. Dos 467 casos de hipoacusia sensorioneural, incluíram-se aqueles que apresentavam PEATC sem resposta ou com resposta marcadamente anormal e OEAs presentes e/ou limiares tonais desproporcionais aos resultados electrofisiológicos. Obtiveram-se 12 casos de DENA. Resultados: A prevalência de DENA foi 2,6%. A maioria dos casos apresentou factores de risco para hipoacusia. Os resultados audiométricos foram heterogéneos e flutuantes. Quatro crianças foram reabilitadas com prótese auditiva e três com implante coclear. Conclusões: O DENA é uma condição rara, associada a vários factores de risco e de diagnóstico e abordagem desafiantes. A reabilitação auditiva tem de ser personalizada e guiada pelo desempenho funcional da criança.
- A New ABCA3 Gene Mutation Presenting as Early Neonatal Surfactant DeficiencyPublication . Martins de Abreu, S; Oliveira Antunes, D; Abreu, FMutations of the ATP-binding cassette transporter A3 gene (ABCA3) causing the dysfunction of surfactant proteins are a well-established cause of interstitial lung disease. The clinical presentation is variable ranging from neonatal early death to mild forms of interstitial lung disease in the adult. We present the case of a newborn with early neonatal respiratory distress. The clinical and radiologic findings were compatible with interstitial lung disease. The disease progressed toward severe respiratory insufficiency and the patient died at the age of 3 years. A variant not yet described in the literature was found in the ABCA3 gene (c.4442C>T), in apparent homozygosity. Parental genetic studies revealed that only the father was a carrier for this variant. The quantitative study of the ABCA3 gene in our patient revealed a deletion affecting exon 32 and possibly 29. This report describes the phenotype of a new ABCA3 variant causing surfactant deficiency while also highlighting the importance of considering gene deletions in case of unconfirmed homozygosity.