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- Copy number variants prioritization after array-CGH analysis - a cohort of 1000 patientsPublication . Carreira, IM; Ferreira, SI; Matoso, E; Pires, LM; Ferrão, J; Jardim, A; Mascarenhas, A; Pinto, M; Lavoura, N; Pais, C; Paiva, P; Simões, L; Caramelo, F; Ramos, L; Venâncio, M; Ramos, F; Beleza, A; Sá, J; Saraiva, J; Barbosa de Melo, JArray-based comparative genomic hybridization has been assumed to be the first genetic test offered to detect genomic imbalances in patients with unexplained intellectual disability with or without dysmorphisms, multiple congenital anomalies, learning difficulties and autism spectrum disorders. Our study contributes to the genotype/phenotype correlation with the delineation of laboratory criteria which help to classify the different copy number variants (CNVs) detected. We clustered our findings into five classes ranging from an imbalance detected in a microdeletion/duplication syndrome region (class I) to imbalances that had previously been reported in normal subjects in the Database of Genomic Variants (DGV) and thus considered common variants (class IV).
- Mutations in SNX14 cause a distinctive autosomal-recessive cerebellar ataxia and intellectual disability syndromePublication . Thomas, AC; Williams, H; Setó-Salvia, N; Bacchelli, C; Jenkins, D; O'Sullivan, M; Mengrelis, K; Ishida, M; Ocaka, L; Chanudet, E; James, C; Lescai, F; Anderson, G; Morrogh, D; Ryten, M; Duncan, AJ; Pai, YJ; Saraiva, JM; Ramos, F; Farren, B; Saunders, D; Vernay, B; Gissen, P; Straatmaan-Iwanowska, A; Baas, F; Wood, NW; Hersheson, J; Houlden, H; Hurst, J; Scott, R; Bitner-Glindzicz, M; Moore, GE; Sousa, SB; Stanier, PIntellectual disability and cerebellar atrophy occur together in a large number of genetic conditions and are frequently associated with microcephaly and/or epilepsy. Here we report the identification of causal mutations in Sorting Nexin 14 (SNX14) found in seven affected individuals from three unrelated consanguineous families who presented with recessively inherited moderate-severe intellectual disability, cerebellar ataxia, early-onset cerebellar atrophy, sensorineural hearing loss, and the distinctive association of progressively coarsening facial features, relative macrocephaly, and the absence of seizures. We used homozygosity mapping and whole-exome sequencing to identify a homozygous nonsense mutation and an in-frame multiexon deletion in two families. A homozygous splice site mutation was identified by Sanger sequencing of SNX14 in a third family, selected purely by phenotypic similarity. This discovery confirms that these characteristic features represent a distinct and recognizable syndrome. SNX14 encodes a cellular protein containing Phox (PX) and regulator of G protein signaling (RGS) domains. Weighted gene coexpression network analysis predicts that SNX14 is highly coexpressed with genes involved in cellular protein metabolism and vesicle-mediated transport. All three mutations either directly affected the PX domain or diminished SNX14 levels, implicating a loss of normal cellular function. This manifested as increased cytoplasmic vacuolation as observed in cultured fibroblasts. Our findings indicate an essential role for SNX14 in neural development and function, particularly in development and maturation of the cerebellum.
- Intellectual disability, coarse face, relative macrocephaly, and cerebellar hypotrophy in two sistersPublication . Sousa, SB; Ramos, F; Garcia, P; Pais, RP; Paiva, C; Beales, PL; Moore, GE; Saraiva, JM; Hennekam, RCWe report on two Portuguese sisters with a very similar phenotype characterized by severe intellectual disability, absent speech, relative macrocephaly, coarse face, cerebellar hypotrophy, and severe ataxia. Additional common features include increased thickness of the cranial vault, delayed dental eruption, talipes equino-varus, clinodactyly, and camptodactyly of the fifth finger. The older sister has retinal dystrophy and the younger sister has short stature. Their parents are consanguineous. We suggest this condition constitutes a previously unreported autosomal recessive entity.
- Oculo-auriculo-vertebral spectrum: a review of the literature and genetic updatePublication . Beleza-Meireles, AF; Clayton-Smith, J; Saraiva, JM; Tassabehji, MOculo-auriculo-vertebral spectrum (OAVS, OMIM 164 210) is a developmental disorder primarily involving structures derived from the first and second pharyngeal arches during embryogenesis. The phenotype is clinically heterogeneous and is typically characterised by abnormal development of the ear, mandible anomalies and defects of the vertebral column. OAVS may occur as a multiple congenital abnormality, and associated findings include anomalies of the eye, brain, heart, kidneys and other organs and systems. Both genetic and environmental factors are thought to contribute to this craniofacial condition, however, the mechanisms are still poorly understood. Here, we present a review of the literature on OAVS, discussing what is known about the aetiology, candidate loci, possible mechanisms and the range of clinical features that characterise this condition. We also comment on some important aspects of recurrence risk counselling to aid clinical management.
- Dilated fetal bowel as indication for prenatal diagnosis of cystic fibrosisPublication . Soares, R; Neto, P; Pereira, N; Cunha, C; Pinto, C; Fonseca, M; Ramos, L; Galhano, EDilated fetal bowel is a sonographic fi nding that is associated to meconium ileus, a feature of cystic fi brosis (CF). Prenatal diagnosis of CF is possible through analysis of the cystic fi brosis transmembrane regulator gene mutations. A male infant is described, who was referred to our Prenatal Diagnosis Center a 17th week of gestation with a dilated bowel loop on a prenatal scan. Amniocentesis was performed at 23rd week gestation and a homozygous F508del mutation was found. He was born at 38 weeks gestation, after an otherwise unremarkable pregnancy, and admitted to Neonatal Intensive Care Unit. He showed progressive abdominal distension without stools and was transferred to another Hospital to surgery. A total occlusion of terminal ileum with meconium and a microcolon were found, and resection of 8 cm of ileum and an ileostomy were performed. The characteristic sonographic fi nding of a dilated bowel is an indication to search for CF mutations.
- Gain-of-function mutations in the phosphatidylserine synthase 1 (PTDSS1) gene cause Lenz-Majewski syndromePublication . Sousa, SB; Jenkins, D; Chanudet, E; Tasseva, G; Ishida, M; Anderson, G; Docker, J; Ryten, M; Sá, J; Saraiva, JM; Barnicoat, A; Scott, R; Calder, A; Wattanasirichaigoon, D; Chrzanowska, K; Simandlová, M; Van Maldergem, L; Stanier, P; Beales, PL; Vance, JE; Moore, GELenz-Majewski syndrome (LMS) is a syndrome of intellectual disability and multiple congenital anomalies that features generalized craniotubular hyperostosis. By using whole-exome sequencing and selecting variants consistent with the predicted dominant de novo etiology of LMS, we identified causative heterozygous missense mutations in PTDSS1, which encodes phosphatidylserine synthase 1 (PSS1). PSS1 is one of two enzymes involved in the production of phosphatidylserine. Phosphatidylserine synthesis was increased in intact fibroblasts from affected individuals, and end-product inhibition of PSS1 by phosphatidylserine was markedly reduced. Therefore, these mutations cause a gain-of-function effect associated with regulatory dysfunction of PSS1. We have identified LMS as the first human disease, to our knowledge, caused by disrupted phosphatidylserine metabolism. Our results point to an unexplored link between phosphatidylserine synthesis and bone metabolism.
- Intellectual disability, unusual facial morphology and hand anomalies in sibsPublication . Sousa, SB; Venâncio, M; Chanudet, E; Palmer, R; Ramos, L; Beales, PL; Moore, GE; Saraiva, JM; Hennekam, RCHere we report on a Portuguese family with three sisters who shared moderate intellectual disability, unusual facial morphology (short palpebral fissures; broad nasal tip; thin upper and lower vermillion; broad and pointed chin) and hand anomalies in two of them (short left third and fifth right metacarpals in one case; marked syndactyly between the third and fourth fingers in another). One of the sisters had microcephaly and short stature, and the other two were obese. Obesity and somewhat similar facial features were also present in the otherwise healthy mother. Despite the overlap with several known syndromes (Albright osteodystrophy; Filippi syndrome; Rubinstein-Taybi syndrome; microdeletion 2q37), we suggest this condition is previously unreported, and most likely displays an autosomal recessive pattern of inheritance.
- Description of an autosomal dominant form of Kabuki syndrome by mutation in MLL2 genePublication . Santos, MI; Beleza-Meireles, A; Loureiro, S; Fonseca, M; Reis, CF; Rodrigues, F; Ramos, F; Ramos, L; Cardoso, E; Saraiva, JMAims: Although there are more than 400 cases of Kabuki syndrome described in the literature, it is believed that this syndrome is under-diagnosed. Most cases occur sporadically, despite cases with autosomal dominant familial transmission being described. Here we describe three cases identified in the same family. Cases description: A family (mother and two children) was diagnosed with Kabuki syndrome. The three patients show the typical characteristics (facial appearance, musculoskeletal abnormalities, cognitive impairment, growth retardation and peculiar dermatoglyphic pattern) associated with other anomalies described in the syndrome (congenital heart disease and increased susceptibility to infections). Genetic studies revealed a nonsense mutation c.14710 C > T (p.Arg4904X) in the MLL2 gene in the three members of the family. Conclusions: With the description of another case of familial Kabuki syndrome, the authors wish to illustrate the autosomal dominant inheritance with variable expressivity, which are present in this situation, and to alert to the need for a rigorous clinical and molecular evaluation of the affected patient’s relatives, allowing appropriate genetic counseling.
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