A Novel MGP Gene Mutation Causing Keutel Syndrome in a Brazilian Patient

Keutel syndrome is caused by mutations in the matrix gamma-carboxyglutamic acid (MGP) gene (OMIM 154870) and is inherited in an autosomal recessive fashion. It is characterized by brachydactyly, pulmonary artery stenosis, a distinctive facial phenotype, and cartilage calcification. To date, only 36 cases have been reported worldwide. We describe clinical and molecular findings of the first Brazilian patient with Keutel syndrome. Keutel syndrome was suspected based on clinical and morphological evaluation, so we sequenced the MGP gene using the TruSight One Sequencing Panel (Illumina). The obtained MGP gene sequence was then validated by Sanger sequencing. We identified a novel pathogenic homozygous variant of the MGP gene (c.2T>C; p.Met1Thr) confirming Keutel syndrome. Proper diagnosis of this syndrome is important for clinical management and is an indication for genetic counseling. Keutel syndrome should be suspected in patients with cartilage calcifications and brachydactyly when associated with a distinctive facial phenotype and pulmonary artery stenosis.

A novel de novo mutation in MYT1, the unique OAVS gene identified so far

Oculo-auriculo-vertebral spectrum (OAVS) is a developmental disorder characterized by hemifacial microsomia associated with ear, eyes and vertebrae malformations showing highly variable expressivity. Recently, MYT1, encoding the myelin transcription factor 1, was reported as the first gene involved in OAVS, within the retinoic acid (RA) pathway. Fifty-seven OAVS patients originating from Brazil were screened for MYT1 variants. A novel de novo missense variant affecting function, c.323C>T (p.(Ser108Leu)), was identified in MYT1, in a patient presenting with a severe form of OAVS. Functional studies showed that MYT1 overexpression downregulated all RA receptors genes (RARA, RARB, RARG), involved in RA-mediated transcription, whereas no effect was observed on CYP26A1 expression, the major enzyme involved in RA degradation, Moreover, MYT1 variants impacted significantly the expression of these genes, further supporting their pathogenicity. In conclusion, a third variant affecting function in MYT1 was identified as a cause of OAVS. Furthermore, we confirmed MYT1 connection to RA signaling pathway.

Miller-Dieker Syndrome due to a 5.5-Mb 17p Deletion in a 17;Y Pseudodicentric Chromosome

Miller-Dieker syndrome (MDS) is a contiguous gene deletion syndrome in which almost all patients present de novo 17p13.3 deletions. We report on a male infant with MDS and an unusual unbalanced translocation involving chromosomes Y and 17 that resulted in a large 5.5-Mb 17pterp13.2 deletion and a karyotype with 45 chromosomes. Apart from the deletion of the MDS critical region, the deletion of additional distal genes seemed to have no major influence on the patient's phenotype, since he did not show any unusual clinical findings that are not commonly described in MDS patients.

Unusual Duplication in the Pericentromeric Region of Chromosome 9 in a Patient with Phenotypic Alterations

Several alterations involving the pericentromeric region of chromosome 9 are considered as normal population variants. These heterochromatic variants or heteromorphisms can include 9qh+, 9cen+, 9ph+, 9ph-, inv(9)(p11q13), and other patterns which can only be defined by FISH studies. However, some heteromorphisms have been found more frequently in patients with several clinical disorders. Here, we report on a patient with intellectual disability, language and neurodevelopmental delay, as well as facial dysmorphism and an unusual chromosome 9. While the banding karyotype was indicative of a simple pericentric inversion of one chromosome 9 [46,XX,inv(9)(p12q13)], array comparative genomic hybridization showed a 6-Mb duplication, including 22 genes: arr[hg19] 9p13.1p11.2(38,869,901- 44,870,714)×3 dn. Molecular cytogenetics using a panel of probes specific for the pericentromeric region of chromosome 9 showed an unusual, rearranged chromosome 9, der(9)(pter→p11.2::q21.11→q12::p11.2→p13.2::q12→p11.2::q21.11→qter), that has not been described before. The patient's phenotypic alterations are probably due to the de novo 6-Mb 9p duplication, although a review of similar cases showed some reports considering this duplication in the euchromatic region as a benign variant. Interestingly, this is the first report of a possible adverse inversion loop formation due to a known heteromorphic pericentric inversion present in the phenotypically normal father of the patient.

Atypical 581-kb 22q11.21 Deletion in a Patient with Oculo-Auriculo-Vertebral Spectrum Phenotype

The oculo-auriculo-vertebral spectrum (OAVS) is defined as a group of malformations involving the ears, mouth, mandible, eyes, and cervical spine. Establishing an accurate clinical diagnosis of OAVS is a challenge for clinical geneticists, not only because these patients display heterogeneous phenotypes, but also because its etiology encompasses environmental factors, unknown genetic factors and different chromosome aberrations. To date, several chromosomal abnormalities have been associated with the syndrome, most frequently involving chromosome 22. In the literature, six 22q11.2 microdeletions have been described within the same region, suggesting possible OAVS candidate genes in this segment. Here, we report on a patient with an ∼581-kb 22q11.21 deletion, detected by genomic array and MLPA. This is the 7th case described with OAVS and 22q deletion, suggesting that the 22q11.2 region may be related to the regulation of body symmetry and facial development.

Impact of 5-HTTLPR and BDNF polymorphisms on response to sertraline versus transcranial direct current stimulation: implications for the serotonergic system

Transcranial direct current stimulation (tDCS) has been intensively investigated as a non-pharmacological treatment for major depressive disorder (MDD). While many studies have examined the genetic predictors of antidepressant medications, this issue remains to be investigated for tDCS. In the current study, we evaluated whether the BDNF Val66Met and the 5-HTT (5-HTTLPR) polymorphisms were associated with tDCS antidepressant response. We used data from a factorial trial that evaluated the efficacy of tDCS and sertraline and enrolled 120 moderate-to-severe, antidepressant-free participants. In the present study, we used analyses of variance to evaluate whether the BDNF (Val/Val vs. Met-carries) and 5-HTTLPR alleles (long/long vs short-carriers) were predictors of tDCS (active/sham) and sertraline (sertraline/placebo) response. Analyses were conducted on the polymorphisms separately and also on their interaction. Genotype frequencies were in Hardy-Weinberg equilibrium. BDNF polymorphism was not associated with treatment response. We found that 5-HTTLPR predicted tDCS effects as long/long homozygotes displayed a larger improvement comparing active vs. sham tDCS, while short-allele carriers did not. A dose-response relationship between active-sham differences with the long allele was also suggested. These results strengthen the role of the serotonergic system in the tDCS antidepressant effects and expand previous findings that reported that tDCS mechanisms of action partially involve serotonergic receptors. Therefore, we hypothesize that tDCS is a neuromodulation technique that acts over depression through the modulation of serotonergic system and that tDCS "top-down" antidepressant effects might not be optimal in brain networks with a hyperactive amygdala inducing bottom-up effects, such as occurs in short-carriers.

First report of a small supernumerary der(8;14) marker chromosome

Small supernumerary marker chromosomes (sSMC) are structurally abnormal chromosomes, generally equal in size or smaller than a chromosome 20 of the same metaphase spread. Most of them are unexpectedly detected in routine karyotype analyses, and it is usually not easy to correlate them with a specific clinical picture. A small group of sSMCs is derived from more than one chromosome, called complex sSMCs. Here, we report on a patient with a de novo complex sSMC, derived from chromosomes 8 and 14. Banding karyotype analysis, multiplex ligation-dependent probe amplification (MLPA), single nucleotide polymorphism (SNP)-based array, and fluorescence in situ hybridization (FISH) were performed to investigate its origin. Array and FISH analyses revealed a der(14)t(8;14)(p23.2;q22.1)dn. The propositus presents some clinical features commonly found in patients with partial duplication or triplication of 8p and 14q. This is the first report describing a patient with a congenital der(14)t(8;14)(p23.2;q22.1)dn sSMC.

Interstitial 4q Deletion and Isodicentric Y-Chromosome in a Patient with Dysmorphic Features

We present a 2-year-old boy with a de novo 46,XY,idic(Y)(q11.221),del(4)(q26q31.1) karyotype. G-banding, FISH, MLPA, and SNP-array techniques were used to characterize the 24-Mb deletion in 4q and the breakpoint in the isodicentric Y-chromosome region between 15,982,252 and 15,989,842 bp. The patient presented with mild facial dysmorphism, hemangioma, mild frontal cerebral atrophy, and Dandy-Walker variant. Essentially, this case reveals that patients can present more complex genomic imbalances than initially suspected.

Marfan syndrome with a complex chromosomal rearrangement including deletion of the FBN1 gene

Background

The majority of Marfan syndrome (MFS) cases is caused by mutations in the fibrillin-1 gene (FBN1), mapped to chromosome 15q21.1. Only few reports on deletions including the whole FBN1 gene, detected by molecular cytogenetic techniques, were found in literature.

Results

We report here on a female patient with clinical symptoms of the MFS spectrum plus craniostenosis, hypothyroidism and intellectual deficiency who presents a 1.9 Mb deletion, including the FBN1 gene and a complex rearrangement with eight breakpoints involving chromosomes 6, 12 and 15.

Discussion

This is the first report of MFS with a complex chromosome rearrangement involving a deletion of FBN1 and contiguous genes. In addition to the typical clinical findings of the Marfan syndrome due to FBN1 gene haploinsufficiency, the patient presents features which may be due to the other gene deletions and possibly to the complex chromosome rearrangement.

Candidate gene linkage analysis indicates genetic heterogeneity in Marfan syndrome

Marfan syndrome (MFS) is an autosomal dominant disease of the connective tissue that affects the ocular, skeletal and cardiovascular systems, with a wide clinical variability. Although mutations in the FBN1 gene have been recognized as the cause of the disease, more recently other loci have been associated with MFS, indicating the genetic heterogeneity of this disease. We addressed the issue of genetic heterogeneity in MFS by performing linkage analysis of the FBN1 and TGFBR2 genes in 34 families (345 subjects) who met the clinical diagnostic criteria for the disease according to Ghent. Using a total of six microsatellite markers, we found that linkage with the FBN1 gene was observed or not excluded in 70.6% (24/34) of the families, and in 1 family the MFS phenotype segregated with the TGFBR2 gene. Moreover, in 4 families linkage with the FBN1 and TGFBR2 genes was excluded, and no mutations were identified in the coding region of TGFBR1, indicating the existence of other genes involved in MFS. Our results suggest that the genetic heterogeneity of MFS may be greater that previously reported.

TGFBI gene mutations in Brazilian patients with corneal dystrophy

PURPOSE

To investigate the transforming growth factor beta-induced gene (TGFBI) mutations in Brazilian patients with corneal dystrophy and to evaluate the phenotype-genotype correlation in these patients.

METHODS

A total of 11 unrelated families were studied. The diagnosis of corneal dystrophy was based on clinical and histopathological findings. Genomic DNA was extracted from peripheral blood leucocytes, and exons 4 and 12 of the TGFBIgene were amplified by polymerase chain reaction followed by direct sequencing on both strands.

RESULTS

Five different mutations in the TGFBIgene were found in the probands. We identified the following mutations: lattice corneal dystrophy--R124C and A546T; Reis-Bücklers corneal dystrophy--R555Q and R124L; granular corneal dystrophy--R555W and Avellino dystrophy--R555W. In three of the 11 studied families there was no mutation in exons 4 and 12.

CONCLUSIONS

This is the first report of mutations in the TGFBIgene in a series of Brazilian patients with corneal dystrophy. The findings indicate that TGFBIgene screening should be considered in the diagnosis of corneal dystrophy.

Serum total homocysteine levels and the prevalence of folic acid deficiency and C677T mutation at the MTHFR gene in an indigenous population of Amazonia: the relationship of homocysteine with other cardiovascular risk factors

Hyperhomocysteinemia is a risk factor for cardiovascular disease. C677T mutation at the MTHFR gene and deficiencies of folic acid and vitamin B-12 may account for elevation of total homocysteine (tHcy). Ninety Brazilian Parkatêjê Indians (90.0% of the population without admixture, aged > or = 20 years) were studied. Hyperhomocysteinemia was observed in 26.7% of the Indians. No case of vitamin B-12 deficiency was detected. Folic acid deficiency was found in 43.3% of the subjects. Rates of mutated allele 677T and TT genotype were 40.7% and 14.0%, respectively. Prevalence of hypertension, dyslipidemia, smoking, WHR > or = 0.9, BMI > or = 25 kg/m2 and chronic alcohol use were 4.4%, 44.4%, 25.6%, 72.2%, 67.8%, and 0.0%, respectively. All creatinine values were normal. Natural logarithmic (ln) tHcy showed no correlation with age, but was positively correlated with systolic (r = 0.22) and diastolic (r = 0.21) blood pressure and triglycerides (r = 0.39) and inversely correlated with folic acid (r = -0.40) adjusted for age and sex. Total homocysteine (tHcy) was higher among TT genotype (P < .001). The multiple linear regression model, containing variables for sex, folic acid, TT genotype, and triglycerides, explained 50.0% of the variation of the ln tHcy. In summary, high rates of cardiovascular risk factors were discovered. C667T mutation and folic acid deficiency can explain, at least in part, the observed hyperhomocysteinemia.

Increased plasma homocysteine levels in shift working bus drivers

BACKGROUND

Previous studies have indicated an association between shift work and cardiovascular disease. There is also considerable epidemiological evidence that hyperhomocysteinemia is an independent risk factor for cardiovascular disorders.

AIMS

To analyse plasma homocysteine levels in shift work bus drivers, and to investigate possible relations with sleep parameters and other biochemical factors.

METHODS

Blood samples were collected from 30 male shift working long-haul bus drivers in a Brazilian sample and analysed for plasma levels of homocysteine, folic acid, vitamin B(12), and serum lipids. A group of 22 daytime workers, matched for age and body mass index served as controls. The incidence of mutations in the gene coding for methylene tetrahydrofolate, an enzyme which is related to hyperhomocysteinemia, was also assessed. Polysomnographic recordings were obtained from the target group.

RESULTS

Bus drivers showed significantly higher levels of plasma homocysteine than the control group (18.57 v 9.43 micro M). Most of the other biochemical, behavioural, and molecular parameters did not differ between groups. Likewise, sleep parameters appeared to be within the normal range.

CONCLUSIONS

The significantly increased plasma homocysteine levels in long-haul bus drivers did not appear to be secondary to other biochemical or behavioural problems in this group. These results suggest that hyperhomocysteinemia may be involved in the increased incidence of cardiovascular diseases observed in shift workers.