SELAdb: A database of exonic variants in a Brazilian population referred to a quaternary medical center in São Paulo

OBJECTIVES: High-throughput sequencing of genomes, exomes, and disease-focused gene panels is becoming increasingly common for molecular diagnostics. However, identifying a single clinically relevant pathogenic variant among thousands of genetic polymorphisms is a challenging task. Publicly available genomic databases are useful resources to filter out common genetic variants present in the population and enable the identification of each disease-causing variant. Based on our experience applying these technologies at Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (HCFMUSP), São Paulo, Brazil, we recognized that the Brazilian population is not adequately represented in widely available genomic databases. METHODS: Here, we took advantage of our 5-year experience as a high-throughput sequencing core facility focused on individuals with putative genetic disorders to build a genomic database that may serve as a more accurate reference for our patient population: SELAdb. RESULTS/CONCLUSIONS: Currently, our database comprises a final cohort of 523 unrelated individuals, including patients or family members managed by different clinics of HCFMUSP. We compared SELAdb with other publicly available genomic databases and demonstrated that this population is very heterogeneous, largely resembling Latin American individuals of mixed origin, rather than individuals of pure European ancestry. Interestingly, exclusively through SELAdb, we identified a spectrum of known and potentially novel pathogenic variants in genes associated with highly penetrant Mendelian disorders, illustrating that pathogenic variants circulating in the Brazilian population that is treated in our clinics are underrepresented in other population databases. SELAdb is freely available for public consultation at: http://intranet.fm.usp.br/sela

Mutações no gene do receptor do fator de crescimento insulina-símile 1 (IGF1R) como causa de retardo do crescimento pré- e pós-natal / Mutations in insulin-like growth factor receptor 1 gene (IGF1R) resulting in intrauterine and postnatal growth retardation

Aproximadamente 10 por cento das crianças nascidas pequenas para a idade gestacional (PIGs) não apresentam recuperação espontânea do crescimento. As causas desse déficit de crescimento pré-natal e sua manutenção após o nascimento ainda não são completamente conhecidas na maioria dos casos. Nos últimos oito anos, diversas mutações inativadoras e deleções do gene IGF1R em heterozigose foram relatadas, indicando o papel de defeitos no eixo IGFs/IGF1R como causa do déficit de crescimento. Postula-se que pelo menos 2,5 por cento das crianças nascidas PIGs possam apresentar defeitos no gene IGF1R. O quadro clínico desses pacientes apresenta grande variabilidade quanto à gravidade do retardo de crescimento e aos parâmetros hormonais. Nos casos mais evidentes, os pacientes apresentam microcefalia, déficit cognitivo leve e valores elevados de IGF-1, associados à baixa estatura de início pré-natal. Esta revisão abordará os aspectos clínicos, moleculares e do tratamento da baixa estatura com hrGH de crianças com mutações no IGF1R.

Approximately 10 percent of children born small-for-gestational age (SGA) do not show spontaneous growth catch-up. The causes of this deficit in prenatal growth and its maintenance after birth are not completely known, in most cases. Over the past eight years, several heterozygous inactivating mutations and deletions in IGF1R gene have been reported, indicating the role of defects in the IGFs/IGF1R axis as a cause of growth deficit. It has been hypothesized that at least 2.5 percent of children born SGA may have IGF1R gene defects. The clinical presentation of these patients is highly variable in the severity of growth retardation and hormonal parameters. In the most evident cases, patients have microcephaly, mild cognitive impairment and high levels of IGF-1, associated with short stature of prenatal onset. This review will describe the clinical, molecular and treatment of short stature with hrGH of children with mutations in the IGF1R gene.