Unrelated Brazilian Patients Research Articles

A novel mutation of IL1RN in the deficiency of interleukin-1 receptor antagonist syndrome: Description of two unrelated cases from Brazil

Monogenic autoinflammatory diseases are disorders of Mendelian inheritance that are characterized by mutations in genes that regulate innate immunity and whose typical features are systemic inflammation without high-titer autoantibodies or antigen-specific T cells. Skin and bone inflammation in the newborn period have been described in 3 of these autoinflammatory disorders: neonatal-onset multisystem inflammatory disease, Majeed syndrome, and deficiency of interleukin-1 (IL-1) receptor antagonist (DIRA) syndrome. This study was undertaken to present the characteristics of the DIRA syndrome in 2 cases from Brazil, and describe a novel mutation in IL1RN. Two unrelated Brazilian patients were evaluated for the clinical signs and symptoms of these 3 disorders, and peripheral blood samples were assessed for mutations in NLRP3, LPIN2, and IL1RN by DNA resequencing analysis. A mutation in IL1RN that encodes a mutant protein was identified, and the expression and function of this mutant protein were compared to those of the wild-type protein. Both patients presented with pustular dermatitis resembling generalized pustular psoriasis, recurrent multifocal aseptic osteomyelitis, and elevation in the levels of acute-phase reactants, all of which are features most consistent with the DIRA syndrome. Chronic lung disease was observed in 1 of the patients, and jugular venous thrombosis was observed in the other patient. Both patients showed a partial response to corticosteroid therapy, and 1 patient experienced an initial improvement of dermatitis with the use of acitretin. Both patients were homozygous for a novel 15-bp (in-frame) deletion on the IL1RN gene. The mutated protein expressed in vitro had no affinity with the IL-1 receptor, and stimulation of the patients' cells with recombinant human IL-1α or IL-1β led to oversecretion of proinflammatory cytokines, similar to the findings obtained in previously reported patients. The presence of the same homozygous novel mutation in IL1RN in 2 unrelated Brazilian patients suggests that this genetic variant may be a founder mutation that has been introduced in the Brazilian population.

Searching for Digenic Inheritance in Deaf Brazilian Individuals Using the Multiplex Ligation-Dependent Probe Amplification Technique

Mutations in the genes coding for connexin 26 (Cx26), connexin 30 (Cx30), and connexin 31 (Cx31) are the main cause of autosomal recessive nonsyndromic sensorineural hearing loss (AR-NSNHL). The 35delG mutation is the most frequent in the majority of Caucasian populations and may account for up to 70% of all GJB2 mutations. As a large number of affected individuals (10%-40%) with GJB2 mutations carry only one mutant allele, it has been postulated that the presence of additional mutations in the GJB6 gene (Cx30) explains the deafness condition found in these patients. In the present study, we screened the c.35delG mutation in ~600 unrelated Brazilian patients, with moderate to profound AR-NSNHL. Other point mutations in the coding region of the GJB2 gene were screened by sequencing analysis as well as the IVS 1+1 G>A splice site mutation in the same gene. Digenic mutations including large deletions and duplications were investigated in the Cx26, 30, and 31 genes in monoallelic individuals for mutations in the GJB2 gene. Large deletions and duplications were assessed by multiplex ligation-dependent probe amplification. We found 46 patients with mutations in only one GJB2 allele. Different pathogenic mutations associated with c.35delG were found in 13 patients. Two patients were identified with digenic heterozygous mutations. Our findings contributed to more accurate diagnosis and more appropriate genetic counseling in 28% of patients studied (13/46).

Leber’s hereditary optic neuropathy: Clinical and molecular profile of a Brazilian sample

Purpose: The aim of this study was to describe clinical features and search for primary mitochondrial DNA (mtDNA) mutations in 13 unrelated Brazilian patients with Leber’s hereditary optic neuropathy (LHON).Methods: Analysis of the G11778A, G3460A, and T14484C mutations was done by polymerase chain reaction and restriction fragment length polymorphism, and mutations were confirmed by direct sequencing. Mean age of onset was 24.5 years and all cases were bilateral.Results: Sex ratio (12M:1F) and frequency of simultaneous involvement (9/13) were higher than in other studies. In nine cases there was familial recurrence: 24 male and two female relatives. Ten patients had a mutation: G11778A in six, T14484C in three and one G3460A. The frequency of patients bearing a primary mutation was lower than that described in multicentric studies but similar to that observed among Asians. A higher frequency of the T14484C mutation was detected.Conclusions: The contribution of Amerindians and Africans to the Brazilian mtDNA pool may account for differences in the type and frequency of primary LHON mutations.

Screening for the GJB2 c.-3170 G>A (IVS 1+1 G>A) Mutation in Brazilian Deaf Individuals Using Multiplex Ligation–Dependent Probe Amplification

Mutations in GJB2 gene are the most common cause of nonsyndromic sensorineural recessive hearing loss. One specific mutation, c.35delG, is the most frequent in the majority of Caucasian populations and may account for up to 70% of all GJB2 mutations. However, 10-40% of the patients carry only one pathogenic mutation in the GJB2 gene. Deletions del(GJB6-D13S1830) and del(GJB6-D13S1854), truncating the GJB6 gene, have been detected in GJB2 heterozygous patients in different populations. The IVS 1+1 G>A splice site mutation in the noncoding region of the GJB2 gene has been found in heterozygous state in addition to c.35delG mutation. This mutation has not been reported in Brazilian deaf patients. In the present study we investigated the presence of the IVS 1+1 G>A mutation by multiplex ligation-dependent probe amplification in 185 unrelated Brazilian patients with autosomal recessive nonsyndromic sensorineural hearing loss (43 heterozygous patients and 142 without any pathogenic mutation in the GJB2-coding region). We have found two patients (4.6%) carrying the IVS 1+1 G>A mutation in compound heterozygous with c.35delG mutation.

Heminasal Aplasia: Clinical Picture, Radiological Findings and Early “Temporary” Reconstruction with a Nasolabial Flap

Heminasal Aplasia: Clinical Picture, Radiological Findings and Early “Temporary” Reconstruction with a Nasolabial Flap

Holoprosencephaly spectrum, ano/microphthalmia, and first branchial arch defects: evidence for a new disorder

We report on three unrelated Brazilian patients with a holoprosencephaly phenotype, with variable central nervous system involvement, ano/microphthalmia, and first branchial arch anomalies. The features of these patients show a striking similarity to those of the patients reported by Guion-Almeida et al. (1999) and Ribeiro et al. (2005), thus confirming the existence of this rare condition. All cases are isolated and the etiology remains unknown.

A study of LRRK2 mutations and Parkinson's disease in Brazil

Mutations in the Leucine-rich repeat kinase 2 (LRRK2) gene are known as a common cause of Parkinson's disease (PD) among patients from different geographic origins. In this study, we evaluated the prevalence of LRRK2 mutations in exons 31 and 41 in a cohort of 154 consecutive, unrelated Brazilian patients with familial or sporadic PD, including early and late onset patients. The LRRK2 p.G2019S mutation was present in heterozygous state in three index cases (approximately 2%), and in three additional relatives. No carriers of this mutation were found among 250 control chromosomes. Clinically, all mutation-positive patients presented a typical PD phenotype and a good response to levodopa. Mutation segregation analysis in a large sibling showed incomplete penetrance of the p.G2019S. Our findings suggest that the LRRK2 p.G2019S mutation has a substantial contribution to PD susceptibility among Brazilian population and add new clues to current research of this disease.

Molecular genetics study of deafness in Brazil: 8‐year experience

Hereditary hearing loss is a complex disorder that involves a large number of genes. In developed countries, 1 in 1,000 children is born with deafness severe enough to require special education services, and about 60% of the cases of isolated deafness have a genetic origin. Although more than 100 genes for hearing loss are known currently, only a few are routinely tested in the clinical practice. In this study, we present our findings from the molecular diagnostic screening of the GJB2 and GJB3 genes, del(GJB6-D13S1,830) and del(GJB6-D13S1,854) deletions in the GJB6 gene, Q829X mutation in the otoferlin gene (OTOF) and, the A1,555G and A7,445G mutations in the mitochondrial genome over an 8-year period. Mutations analysis in the previously mentioned genes and mutations was performed on 645 unrelated Brazilian patients with hearing loss who fell into two different testing groups. Different mutations in the GJB2 gene were responsible for most of cases studied, but deletions in the GJB6 gene as well as mitochondrial mutations were also found. While most cases of hearing loss in this country are due to environmental factors, the genetic etiology of deafness will increasingly be determined as more genetic tests become available.

High frequency of mutation G377S in Brazilian type 3 Gaucher disease patients

Gaucher disease (GD), the most prevalent lysosome storage disorder, presents an autosomal recessive mode of inheritance. It is a paradigm for therapeutic intervention in medical genetics due to the existence of effective enzyme replacement therapy. We report here the analysis of GD in 262 unrelated Brazilian patients, carried out in order to establish the frequency of the most common mutations and to provide prognostic information based on genotype-phenotype correlations. Among 247 type 1 GD patients, mutation N370S was detected in 47% of all the alleles, but N370S/N370S homozygosity was found in only 10% of the patients, a much lower frequency than expected, suggesting that most individuals presenting this genotype may not receive medical attention. Recombinant alleles were detected at a high frequency: 44% of the chromosomes bearing mutation L444P had other mutations derived from the pseudogene sequence, present in 25% of patients. Three neuronopathic type 2 patients were homozygous for L444P, all presenting additional mutations (E326K or recombinant alleles) that probably lead to the more severe phenotypes. Six children, classified as type 1 GD patients, had a L444P/L444P genotype, showing that neuronopathic symptoms may only manifest later in life. This would indicate the need for a higher treatment dose during enzyme replacement therapy. Finally, mutation G377S was present in 4 homozygous type 1 patients and also in compound heterozygosity in 5 (42%) type 3 patients. These findings indicate that G377S cannot be unambiguously classified as mild and suggest an allele-dose effect for this mutation.

High frequency of mutation G377S in Brazilian type 3 Gaucher disease patients

Gaucher disease (GD), the most prevalent lysosome storage disorder, presents an autosomal recessive mode of inheritance. It is a paradigm for therapeutic intervention in medical genetics due to the existence of effective enzyme replacement therapy. We report here the analysis of GD in 262 unrelated Brazilian patients, carried out in order to establish the frequency of the most common mutations and to provide prognostic information based on genotype-phenotype correlations. Among 247 type 1 GD patients, mutation N370S was detected in 47% of all the alleles, but N370S/N370S homozygosity was found in only 10% of the patients, a much lower frequency than expected, suggesting that most individuals presenting this genotype may not receive medical attention. Recombinant alleles were detected at a high frequency: 44% of the chromosomes bearing mutation L444P had other mutations derived from the pseudogene sequence, present in 25% of patients. Three neuronopathic type 2 patients were homozygous for L444P, all presenting additional mutations (E326K or recombinant alleles) that probably lead to the more severe phenotypes. Six children, classified as type 1 GD patients, had a L444P/L444P genotype, showing that neuronopathic symptoms may only manifest later in life. This would indicate the need for a higher treatment dose during enzyme replacement therapy. Finally, mutation G377S was present in 4 homozygous type 1 patients and also in compound heterozygosity in 5 (42%) type 3 patients. These findings indicate that G377S cannot be unambiguously classified as mild and suggest an allele-dose effect for this mutation.

Encephalocraniocutaneous Lipomatosis: Clinical Spectrum of Systemic Involvement

Encephalocraniocutaneous lipomatosis is a rare neurocutaneous syndrome with involvement of ectomesodermal tissues. Unilateral lipomatous hamartomas of the scalp and eyes are the hallmarks of this disorder. Associated findings are extremely variable, ranging from minor abnormalities to severe, debilitating disease. We report two unrelated Brazilian patients with encephalocraniocutaneous lipomatosis, one presenting with the full-blown spectrum of cutaneous, ocular, and central nervous system manifestations, and the other with minor extracutaneous manifestations after a 5-year follow-up period.

Polycythemia and Hb Coimbra [beta 99 (G1) Asp -> Glu] in Brazil

We report the clinical and laboratory findings concerning three unrelated Brazilian patients investigated for polycythemia, whose definitive diagnosis could only be established after the presence of Hb Coimbra (b99 Asp ® Glu) was demonstrated. This illustrates the importance of properly investigating hereditary hemoglobinopathies in cases of erythrocytosis because in some populations variants with high oxygen affinity may be more frequent than expected but go undetected when conventional electrophoresis is used as the sole detection procedure.

Founder effect for the highly prevalent R337H mutation of tumor suppressor p53 in Brazilian patients with adrenocortical tumors

The incidence of adrenocortical tumors in children from the Southern region of Brazil is higher than in other parts of the world. This fact has been related to the identification of an inherited missense mutation of the p53 (R337H) at high frequency (78-97%) in Brazilian children with adrenocortical tumors. Given the high frequency of this germline mutation in the Brazilian population, it is very likely that the R337H mutation has arisen from a common origin. In this study, we analyzed two highly polymorphic intragenic markers (VNTRp53 and p53CA) in 22 patients (16 children and 6 adults) with adrenocortical tumors carrying the germline R337H mutation and 60 normal individuals using GeneScan Fragment Analysis software. We found six and sixteen different alleles for the VNTRp53 and p53CA polymorphic markers, respectively. Two distinct alleles, both with 122 bp, were found in 56.8% (VNTRp53) and 54.5% (p53CA) of the 44 alleles from patients with adrenocortical tumors associated with the R337H mutation. Differently, these same VNTRp53 and p53CA alleles were found in 18.3% and 14.2% of 120 alleles from normal individuals, respectively (p<0.01, Chi-square test). An identical haplotype for p53 locus was also identified in 95% of the apparently unrelated Brazilian patients with adrenocortical tumors carrying the R337H mutation. In conclusion, we demonstrated a strong evidence of co-segregation between two intragenic polymorphic p53 markers and the germline R337H mutation, indicating that this mutation has originated from a single common ancestral in the great majority of the Brazilian patients with adrenocortical tumors.

Newly recognized syndrome with heminasal aplasia and ocular anomalies or wider spectrum of heminasal aplasia/atypical clefting syndrome?

We report on five unrelated Brazilian patients with heminasal aplasia associated with diverses anomalies, including lateral proboscis, and anomalies of the eye and first branchial arch. We suggest that these patients represent different conditions within the spectrum of the heminasal aplasia malformation. Clinical, genetic, and differential diagnosis are discussed.

Molecular basis of familial hypercholesterolemia in Brazil: Identification of seven novel LDLR gene mutations.

Low-density lipoprotein receptor (LDLR) gene mutations cause familial hypercholesterol-emia (FH), one of the most common single gene disorders. The spectrum of LDLR mutations in Brazil is not known. The aim of this study was the characterization of LDLR mutations in 35 unrelated Brazilian patients with heterozygous FH. The promoter region, the 18 exons and the flanking intron sequences of the LDLR gene were screened by PCR-SSCP analysis and by DNA sequencing. In addition, we have screened the apolipoprotein B gene (APOB) for known mutations (R3500Q and R3531C) that cause Familial defective apo B-100 (FDB) by PCR-RFLP procedure. We found two nonsense (E92X and C371X) and six missense LDLR mutations (R236W, G322S, G352D, A370T, C675W and C677Y), that were previously described in FH patients from other populations. We also found five novel missense [G(-20)R, T476P, V503G, D580H and S652R] and two novel frame shift LDLR mutations (FsR757 and FsS828). Four patients were found to carry two different mutations in the LDLR gene: G352D and A370T (one patient), S652R and C675W (one patient) and T476P and V503G (two patients). APOB mutations were not found. These findings demonstrate that there is a broad spectrum of mutations in the LDLR gene in FH individuals from Brazil.

Porphobilmogen deaminase gene mutations in Brazilian acute intermittent porphyria patients.

Acute intermittent porphyria (AIP) is an autosomal dominant disorder resulting from porphobilmogen deaminase (PBGD) deficiency. Seven unrelated Brazilian patients were investigated regarding PBGD gene mutations by polymerase chain reaction (PCR) and single strand conformation polymorphism (SSCP) analysis followed by direct DNA sequencing. The PBG gene screening disclosed abnormal SSCP patterns in exons 7, 9, 12, 13, and 15, as well as in introns 3 and 10. Direct DNA sequencing revealed the occurrence of three nonsense mutations (R149X, R225X, and R325X) in exons 9, 12, and 15, respectively, and one missense mutation G111R in exon 7. The G111R mutation was detected in two unrelated patients. Intragenic polymorphisms (3119G/T in intron 2, 3581G/A in intron 3, 7052A/G and 7064C/A in intron 10, and -65C/T in exon 1) were also observed. In addition, two silent mutations (V202V in exon 10 and A266A in exon 13) were found. The latter has not heretofore been reported. Thus, this study revealed the mutations involved in Brazilian symptomatic AIP patients, as well as the intragenic polymorphisms found in the patients.

Oculo-auriculo-vertebral complex and uncommon associated anomalies: report on 8 unrelated Brazilian patients.

We report on 8 Brazilian patients with the oculo-auriculo-vertebral (OAV) complex with associated uncommon anomalies of hydrocephalus, porencephalic cyst, hand abnormalities, terminal/paraxial hemimelia, Klippel-Feil anomaly, Rokitansky sequence, fibrous dysplasia, and dextrocardia. Our patients show that in some instances a definite diagnosis can be difficult within the wide clinical picture of the OAV complex.