Establishment of iPSC lines and zebrafish with loss-of-function AHDC1 variants: models for Xia-Gibbs syndrome

Xia-Gibbs syndrome (XGS) is a syndromic form of intellectual disability caused by heterozygous AHDC1 variants, but the pathophysiological mechanisms underlying this syndrome are still unclear. In this manuscript, we describe the development of two different functional models: three induced pluripotent stem cell (iPSC) lines with different loss-of-function (LoF) AHDC1 variants, derived by reprogramming peripheral blood mononuclear cells from XGS patients, and a zebrafish strain with a LoF variant in the ortholog gene (ahdc1) obtained through CRISPR/Cas9-mediated editing. The three iPSC lines showed expression of pluripotency factors (SOX2, SSEA-4, OCT3/4, and NANOG). To verify the capacity of iPSC to differentiate into the three germ layers, we obtained embryoid bodies (EBs), induced their differentiation, and confirmed the mRNA expression of ectodermal, mesodermal, and endodermal markers using the TaqMan hPSC Scorecard. The iPSC lines were also approved for the following quality tests: chromosomal microarray analysis (CMA), mycoplasma testing, and short tandem repeat (STR) DNA profiling. The zebrafish model has an insertion of four base pairs in the ahdc1 gene, is fertile, and breeding between heterozygous and wild-type (WT) animals generated offspring in a genotypic proportion in agreement with Mendelian law. The established iPSC and zebrafish lines were deposited on the hpscreg.eu and zfin.org platforms, respectively. These biological models are the first for XGS and will be used in future studies that investigate the pathophysiology of this syndrome, unraveling its underlying molecular mechanisms.

Lipoprotein glomerulopathy associated with the Osaka/Kurashiki APOE variant: two cases identified in Latin America

Background

Lipoprotein glomerulopathy (LPG) is a rare autosomal dominant disease caused by mutations in APOE, the gene which encodes apolipoprotein E. LPG mainly affects Asian individuals, however occasional cases have also been described in Americans and Europeans. Herein we report two unrelated Brazilian patients with LPG in whom genetic analyses revealed the APOE-Osaka/Kurashiki variant.

Case presentation - case 1

A 29-year-old Caucasian male sought medical attention with complaints of face swelling and foamy urine for the last 3 months. He denied a family history of kidney disease, consanguinity, or Asian ancestry. His tests showed proteinuria of 12.5 g/24 h, hematuria, serum creatinine 0.94 mg/dL, albumin 2.3 g/dl, total cholesterol 284 mg/dL, LDL 200 mg/dL, triglycerides 175 mg/dL, and negative screening for secondary causes of glomerulopathy. A kidney biopsy revealed intraluminal, laminated deposits of hyaline material in glomerular capillaries consistent with lipoprotein thrombi. These findings were confirmed by electron microscopy, establishing the diagnosis of LPG. His apolipoprotein E serum level was 72 mg/dL and genetic analysis revealed the APOE pathogenic variant c.527G > C, p.Arg176Pro in heterozygosis, known as the Osaka/Kurashiki mutation and positioned nearby the LDL receptor binding site.

Case 2

A 34-year-old Caucasian man sought medical assessment for renal dysfunction and hypertension. He reported intermittent episodes of lower-limb edema for 3 years and a family history of kidney disease, but denied Asian ancestry. Laboratorial tests showed BUN 99 mg/dL, creatinine 10.7 mg/dL, total cholesterol 155 mg/dL, LDL 79 mg/dL, triglycerides 277 mg/dL, albumin 3.1 g/dL, proteinuria 2.7 g/24 h, and negative screening for secondary causes of glomerulopathy. His kidney biopsy was consistent with advanced chronic nephropathy secondary to LPG. A genetic analysis also revealed the Osaka/Kurashiki variant. He was transplanted a year ago, displaying no signs of disease relapse.

Conclusion

We report two unrelated cases of Brazilian patients with a diagnosis of lipoprotein glomerulopathy whose genetic assessment identified the APOE-Osaka/Kurashiki pathogenic variant, previously only described in eastern Asians. While this is the second report of LPG in Latin America, the identification of two unrelated cases by our medical team raises the possibility that LPG may be less rare in this part of the world than currently thought, and should definitely be considered when nephrotic syndrome is associated with suggestive kidney biopsy findings.

Neurofibromatosis: part 2 – clinical management

Part 1 of this guideline addressed the differential diagnosis of the neurofibromatoses (NF): neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2) and schwannomatosis (SCH). NF shares some features such as the genetic origin of the neural tumors and cutaneous manifestations, and affects nearly 80 thousand Brazilians. Increasing scientific knowledge on NF has allowed better clinical management and reduced rate of complications and morbidity, resulting in higher quality of life for NF patients. Most medical doctors are able to perform NF diagnosis, but the wide range of clinical manifestations and the inability to predict the onset or severity of new features, consequences, or complications make NF management a real clinical challenge, requiring the support of different specialists for proper treatment and genetic counseling, especially in NF2 and SCH. The present text suggests guidelines for the clinical management of NF, with emphasis on NF1.

Neurofibromatose tipo 1: aspectos radiológicos do tórax

OBJETIVO: Identificar alterações e frequências nas radiografias simples do tórax sugestivas de neurofibromatose tipo 1 e avaliar a possibilidade de inclusão de massa no mediastino posterior como critério de diagnóstico de neurofibromatose tipo 1. MATERIAIS E MÉTODOS: Foram realizadas radiografias com técnica padrão de tórax em póstero-anterior e em perfil de 141 pacientes com neurofibromatose tipo 1, atendidos no Serviço de Radiologia do Hospital de Base e Faculdade de Medicina de São José do Rio Preto, SP. Os resultados obtidos foram avaliados por métodos não paramétricos ao nível de 0,05 de significância (p = 0,05). RESULTADOS: No presente estudo, 141 pacientes com neurofibromatose tipo 1 realizaram radiografia de tórax, sendo as alterações mais frequentes: erosão óssea das costelas (19,8%), peito escavado (12,0%), cifoescoliose (3,5%) e massas no mediastino posterior (7,1%). Esses resultados sugerem que as massas (neurofibroma e meningocele) devem ser incluídas como critério diagnóstico para neurofibromatose tipo 1, juntamente com displasia do osso esfenoide, pseudoartrose e afinamento do córtex de ossos longos, conforme definido pelo National Institutes of Health. CONCLUSÃO: A presença das massas no mediastino posterior associada às alterações ósseas características definidas pelo National Institutes of Health indicam ser um achado consistente para se considerar como critério diagnóstico da doença.

Methylenetetrahydrofolate reductase gene polymorphism and its association with coronary artery disease

CONTEXT AND OBJECTIVE

Obstructive coronary artery disease (CAD) is characterized by the deposition of atherosclerotic plaque on the coronary artery wall. Its manifestations depend on interactions between environmental and genetic risk factors. The aim of this work was to analyze the frequency of methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism in patients with CAD and its association with plasma homocysteine levels. Risk factors for CAD were also evaluated.

DESIGN AND SETTING

Retrospective with blind quantitative analysis, at Hospital de Base, Faculdade de Medicina de São José do Rio Preto.

METHODS

One hundred and twenty-seven individuals were studied. All completed a questionnaire to analyze risk factors for CAD. MTHFR polymorphism was investigated by restriction fragment length analysis and correlated with the number of affected arteries and degree of arterial obstruction determined by coronary cineangiography, and with plasma homocysteine levels measured by liquid chromatography/sequential mass spectrometry.

RESULTS

Smoking (p = 0.02) and high-density lipoprotein cholesterol (p = 0.01) were associated with CAD. The C allele was the most prevalent in patients (0.61) and controls (0.66). There was no correlation between MTHFR/C677T polymorphism and plasma homocysteine levels. However, in patients with the TT genotype there was a correlation with the prevalence of coronary obstruction greater than 95% (p = 0.02) and the presence of two affected arteries (p = 0.04).

CONCLUSIONS

The TT genotype is associated with coronary artery obstruction greater than 95% and the presence of two affected arteries. This confirms the relationship between genetic variants in specific patient subgroups and cardiovascular diseases.

Prevalence of the GJB2 mutations and the del(GJB6-D13S1830) mutation in Brazilian patients with deafness

Mutations in the GJB2 gene are the most common cause of sensorineural non-syndromic deafness in different populations. One specific mutation, 35delG, has accounted for the majority of the mutations detected in the GJB2 gene in many countries. The aim of this study was to determine the prevalence of GJB2 mutations and the del(GJB6-D13S1830) mutation in non-syndromic deaf Brazilians. The 33 unrelated probands were examined by clinical evaluation to exclude syndromic forms of deafness. Mutation analysis in the GJB2 gene and the testing for the del(GJB6-D13S1830) were performed in both the patients and their family members. The 35delG mutation was found in nine of the probands or in 14 of the mutated alleles. The V37I mutation and the del(GJB6-D13S1830) mutation were also found in two patients, both are compound heterozygote with 35delG mutation. These findings strengthen the importance of genetic diagnosis, providing early treatment, and genetic counseling of deaf patients.

Puberdade e crescimento em crianças e adolescentes com neurofibromatose tipo 1

BACKGROUND

This study evaluates anthropometric and pubertal development parameters in children and adolescents with sporadic and familial occurrence of neurofibromatosis type 1 (NF-1).

METHODS

The study involved 23 patients (15 boys, 8 girls) with sporadic (n=12) and familial NF-1(7 affected mothers and 4 fathers), with average age of 12 years (range 5-20 years). All patients answered to a standard questionnaire including family and personal data and, following, they underwent systematized physical examination, with special attention to anthropometric data, dermatologic and pubertal stage according to Tanner's criteria evaluation.

RESULTS

Short stature was detected in a 17 year-old patient, 148.5cm height, with score Z of -4.16 and being the even outside of the family conduit. Three male patients had head circumference above of + 2DP from on average for the age. It was not found no case of precocious or delayed puberty.

CONCLUSIONS

In our study, do not we find significant alterations regarding the stature and pubertal development.