Spectrum of FOXL2 gene mutations in blepharophimosis-ptosis-epicanthus inversus (BPES) families demonstrates a genotype--phenotype correlation

Mutations in FOXL2, a forkhead transcription factor gene, have recently been shown to cause blepharophimosis-ptosis-epicanthus inversus syndrome (BPES) types I and II, a rare genetic disorder. In BPES type I a complex eyelid malformation is associated with premature ovarian failure (POF), whereas in BPES type II the eyelid defect occurs as an isolated entity. In this study, we describe the identification of novel mutations in the FOXL2 gene in BPES types I and II families, in sporadic BPES patients, and in BPES families where the type could not be established. In 67% of the patients studied, we identified a mutation in the FOXL2 gene. In total, 21 mutations (17 of which are novel) and one microdeletion were identified. Thirteen of these FOXL2 mutations are unique. In this study, we demonstrate that there is a genotype--phenotype correlation for either types of BPES by the finding that mutations predicted to result in a truncated protein either lacking or containing the forkhead domain lead to BPES type I. In contrast, duplications within or downstream of the forkhead domain, and a frameshift downstream of them, all predicted to result in an extended protein, cause BPES type II. In addition, in 30 unrelated patients with isolated POF no causal mutations were identified in FOXL2. Our study provides further evidence that FOXL2 haploinsufficiency may cause BPES types I and II by the effect of a null allele and a hypomorphic allele, respectively. Furthermore, we propose that in a fraction of the BPES patients the genetic defect does not reside within the coding region of the FOXL2 gene and may be caused by a position effect.

The International SSRI Pharmacogenomics Consortium (ISPC): a genome-wide association study of antidepressant treatment response

Response to treatment with selective serotonin reuptake inhibitors (SSRIs) varies considerably between patients. The International SSRI Pharmacogenomics Consortium (ISPC) was formed with the primary goal of identifying genetic variation that may contribute to response to SSRI treatment of major depressive disorder. A genome-wide association study of 4-week treatment outcomes, measured using the 17-item Hamilton Rating Scale for Depression (HRSD-17), was performed using data from 865 subjects from seven sites. The primary outcomes were percent change in HRSD-17 score and response, defined as at least 50% reduction in HRSD-17. Data from two prior studies, the Pharmacogenomics Research Network Antidepressant Medication Pharmacogenomics Study (PGRN-AMPS) and the Sequenced Treatment Alternatives to Relieve Depression (STAR*D) study, were used for replication, and a meta-analysis of the three studies was performed (N=2394). Although many top association signals in the ISPC analysis map to interesting candidate genes, none were significant at the genome-wide level and the associations were not replicated using PGRN-AMPS and STAR*D data. The top association result in the meta-analysis of response represents SNPs 5′ upstream of the neuregulin-1 gene, NRG1 (P = 1.20E - 06). NRG1 is involved in many aspects of brain development, including neuronal maturation and variations in this gene have been shown to be associated with increased risk for mental disorders, particularly schizophrenia. Replication and functional studies of these findings are warranted.

Three cases of intravenous sodium benzoate and sodium phenylacetate toxicity occurring in the treatment of acute hyperammonaemia

Intravenous sodium benzoate and sodium phenylacetate have been used successfully in the treatment of acute hyperammonaemia in patients with urea cycle disorders. They provide alternative pathways for waste nitrogen disposal and help maintain nitrogen homeostasis. However, we report three patients with hyperammonaemia who received inappropriate doses of intravenous sodium benzoate and sodium phenylacetate that resulted in severe complications. Ambiguous medical prescriptions and inadequate cross-checking of drug dosage by physicians, nurses and pharmacists were the main causes of these incidents. All the patients presented with alteration in mental status, Kussmaul respiration and a partially compensated metabolic acidosis with an increased anion gap. Two patients developed cerebral oedema and hypotension and died. The third survived after haemodialysis. Plasma levels of benzoate and phenylacetate were excessively high. The possible mechanisms of toxicity, management and safety measures are discussed.

Identification of the alpha-aminoadipic semialdehyde dehydrogenase-phosphopantetheinyl transferase gene, the human ortholog of the yeast LYS5 gene

In mammals, L-lysine is first catabolized to alpha-aminoadipate semialdehyde by the bifunctional enzyme alpha-aminoadipate semialdehyde synthase (AASS), followed by a conversion to alpha-aminoadipate by alpha-aminoadipate semialdehyde dehydrogenase. In Saccharomyces cerevisiae, which synthesize rather than degrade lysine, the latter activity requires two distinct genes. LYS2 encodes the alpha-aminoadipate reductase activity, while LYS5 encodes a phosphopantetheinyl transferase activity that is required to activate Lys2p. We have identified a full-length human cDNA homologous to the yeast LYS5 gene. The cDNA contains an open-reading frame of 930 bp predicted to encode 309 amino acids, and the human protein is 26% identical and 44% similar to its yeast counterpart. In Northern blot analysis the cDNA hybridizes to a single transcript of approximately 3 kb in all tissues except testis, where there is an additional transcript of 1.5 kb. Expression is highest in brain followed by heart and skeletal muscle, and to a lesser extent in liver. We further identified three human genomic BAC clones containing the human gene. Fluorescence in situ hybridization (FISH) analysis using the BAC clones mapped the gene to chromosome 11q22 while alignment of the cDNA and genomic sequences allowed partial identification of the intron-exon boundaries. Finally, using one-step homologous recombination in S. cerevisiae we generated a lys5 knockout strain. Complementation studies in the yeast knockout demonstrate that the human homolog encodes alpha-aminoadipate dehydrogenase phosphopantetheinyl transferase activity. We hypothesize that defects in this gene may result in pipecolic acidemia.

Tricho-rhino-phalangeal syndrome with supernumerary teeth

Tricho-rhino-phalangeal syndromes (TRPS) are caused by mutation or deletion of TRPS1, a gene encoding a GATA transcription factor. These disorders are characterized by abnormalities of the hair, face, and selected bones. Rare cases of individuals with TRPS displaying supernumerary teeth have been reported, but none of these has been examined molecularly. We used two different approaches to investigate a possible role of TRPS1 during tooth development. We looked at the expression of Tprs1 during mouse tooth development and analyzed the craniofacial defects of Trps1 mutant mice. In parallel, we investigated whether a 17-year-old Thai boy with clinical features of TRPS and 5 supernumerary teeth had mutation in TRPS1. We report here that Trps1 is expressed during mouse tooth development, and that an individual with TRPS with supernumerary teeth has the amino acid substitution A919V in the GATA zinc finger of TRPS1. These results suggest a role for TRPS1 in tooth morphogenesis.

Association of the Polygenic Scores for Personality Traits and Response to Selective Serotonin Reuptake Inhibitors in Patients with Major Depressive Disorder

Studies reported a strong genetic correlation between the Big Five personality traits and major depressive disorder (MDD). Moreover, personality traits are thought to be associated with response to antidepressants treatment that might partly be mediated by genetic factors. In this study, we examined whether polygenic scores (PGSs) derived from the Big Five personality traits predict treatment response and remission in patients with MDD who were prescribed selective serotonin reuptake inhibitors (SSRIs). In addition, we performed meta-analyses of genome-wide association studies (GWASs) on these traits to identify genetic variants underpinning the cross-trait polygenic association. The PGS analysis was performed using data from two cohorts: the Pharmacogenomics Research Network Antidepressant Medication Pharmacogenomic Study (PGRN-AMPS, n = 529) and the International SSRI Pharmacogenomics Consortium (ISPC, n = 865). The cross-trait GWAS meta-analyses were conducted by combining GWAS summary statistics on SSRIs treatment outcome and on the personality traits. The results showed that the PGS for openness and neuroticism were associated with SSRIs treatment outcomes at p < 0.05 across P_T thresholds in both cohorts. A significant association was also found between the PGS for conscientiousness and SSRIs treatment response in the PGRN-AMPS sample. In the cross-trait GWAS meta-analyses, we identified eight loci associated with (a) SSRIs response and conscientiousness near YEATS4 gene and (b) SSRI remission and neuroticism eight loci near PRAG1, MSRA, XKR6, ELAVL2, PLXNC1, PLEKHM1, and BRUNOL4 genes. An assessment of a polygenic load for personality traits may assist in conjunction with clinical data to predict whether MDD patients might respond favorably to SSRIs.

Cryptic subtelomeric translocations in the 22q13 deletion syndrome

Cryptic subtelomeric rearrangements are suspected to underlie a substantial portion of terminal chromosomal deletions. We have previously described two children, one with an unbalanced subtelomeric rearrangement resulting in deletion of 22q13-->qter and duplication of 1qter, and a second with an apparently simple 22q13-->qter deletion. We have examined two additional patients with deletions of 22q13-->qter. In one of the new patients presented here, clinical findings were suggestive of the 22q13 deletion syndrome and FISH for 22qter was requested. Chromosome studies suggested an abnormality involving the telomere of one 22q (46,XX,?add(22)(q13. 3)). FISH using Oncor D22S39 and Vysis ARSA probes confirmed a terminal deletion. A multi-telomere FISH assay showed a signal from 19qter on the deleted chromosome 22. Results were confirmed with 19qtel and 22qtel specific probes. The patient is therefore trisomic for 19qter and monosomic for 22qter. The patient's mother was found to have a translocation (19;22)(q13.42;q13.31). We also re-examined chromosomes from two patients previously diagnosed with 22q deletions who were not known to have a rearrangement using the multi-telomere assay. One of these patients was found to have a derivative chromosome 22 (der(22)t(6;22)(p25;q13)). No evidence of rearrangement was detected in the other patient. Thus we have found the 22q13 deletion to be associated with a translocation in three of four patients. This report illustrates the usefulness of examining patients with hypotonia, severe language delay, and mild facial dysmorphism for this syndrome and suggests that most of these deletions may be unbalanced subtelomeric rearrangements.

Molecular cytogenetic evaluation in a patient with a translocation (3;21) associated with blepharophimosis, ptosis, epicanthus inversus syndrome (BPES)

Blepharophimosis, ptosis, epicanthus inversus syndrome type I (BPES; OMIM 110100) is an autosomal dominant disorder affecting craniofacial development and ovarian function. We have identified a patient with BPES who carried a de novo reciprocal translocation [46, XX,t(3;21)(q23;q22.1)]. Fluorescence in situ hybridization analysis at band 3q23 using probes derived from BAC 175G20 (Research Genetics), PACs 108L15 and 169C10 (RPCI1), and cosmids AC174D4, AC68D3, AC44F5, and AC125C5 (Lawrence Livermore National Laboratory) was performed. The patient's breakpoint was found to lie within the overlapping region of the BAC and PACs but centromeric to all the cosmids. However, a 10.5-kb BamHI-digested fragment, common to the BAC and PAC clones, was shown to cross the breakpoint. The results have placed our patient's breakpoint proximal to that of the previously reported patient [46,XY,t(3;4)(q23;p15.2)] and within a 10.5-kb interval. This is the second patient in which a breakpoint was refined by molecular cytogenetics. Our findings emphasize the significance of this region for BPES.

The Thai reference exome (T-REx) variant database

To maximize the potential of genomics in medicine, it is essential to establish databases of genomic variants for ethno-geographic groups that can be used for filtering and prioritizing candidate pathogenic variants. Populations with non-European ancestry are poorly represented among current genomic variant databases. Here, we report the first high-density survey of genomic variants for the Thai population, the Thai Reference Exome (T-REx) variant database. T-REx comprises exome sequencing data of 1092 unrelated Thai individuals. The targeted exome regions common among four capture platforms cover 30.04 Mbp on autosomes and chromosome X. 345 681 short variants (18.27% of which are novel) and 34 907 copy number variations were found. Principal component analysis on 38 469 single nucleotide variants present worldwide showed that the Thai population is most genetically similar to East and Southeast Asian populations. Moreover, unsupervised clustering revealed six Thai subpopulations consistent with the evidence of gene flow from neighboring populations. The prevalence of common pathogenic variants in T-REx was investigated in detail, which revealed subpopulation-specific patterns, in particular variants associated with erythrocyte disorders such as the HbE variant in HBB and the Viangchan variant in G6PD. T-REx serves as a pivotal addition to the current databases for genomic medicine.

The relationship of plasma glutamine to ammonium and of glycine to acid-base balance in propionic acidaemia

Hyperammonaemia is a common and serious complication of propionic acidaemia. Treatment of hyperammonaemia with sodium phenylacetate or phenylbutyrate has not been well studied in this disorder. We reviewed the medical records of 5 patients with propionic acidaemia over a 16-year period. We collected information on events where plasma amino acids and ammonium, plasma acids and acid-base balance, or all 3 parameters were obtained simultaneously. All patients were on protein-restricted diet and carnitine throughout the period. In contrast to hyperammonaemia in patients with a urea cycle disorder, plasma glutamine levels were below the normal mean and there was no correlation between plasma ammonium and glutamine levels. The absence of positive correlation between plasma glutamine and ammonium suggests that the routine use of sodium phenylacetate or phenylbutyrate to treat hyperammonaemia in propionic acidaemia should be questioned until further studies are done. Throughout follow-up of our propionic acidaemia patients, we have observed that plasma glycine levels correlated positively with serum bicarbonate. The association of high plasma glycine with good acid-base balance might have a potential role in management and warrants further investigation.

Microcephalic osteodysplastic primordial dwarfism with severe microdontia and skin anomalies: Confirmation of a new syndrome

We report two related Thai children having a new syndrome of microcephalic osteodysplastic primordial dwarfism (MOPD). The findings which classify them as having MOPD include IUGR, microcephaly, prominent nose and nasal bridge, small pinnae, short stature, cone-shaped and ivory-epiphyses, delayed bone age, slender long bones, and abnormal pelvis. The findings that distinguish them as having newly recognized syndrome consist of severe microdontia, malformed teeth, single-rooted or rootless teeth, severely hypoplastic alveolar bone, café au lait spots, acanthosis nigricans, and areas of hypo- and hyperpigmented skin. The reported patients appear to have the same condition as the family reported by Kantaputra [2002: Am J Med Genet 111:420-428]. This article contains supplementary material, which may be viewed at the American Journal of Medical Genetics website at http://www.interscience.wiley.com/jpages/0148-7299/suppmat/index.html.

Insight into the peopling of Mainland Southeast Asia from Thai population genetic structure

There is considerable ethno-linguistic and genetic variation among human populations in Asia, although tracing the origins of this diversity is complicated by migration events. Thailand is at the center of Mainland Southeast Asia (MSEA), a region within Asia that has not been extensively studied. Genetic substructure may exist in the Thai population, since waves of migration from southern China throughout its recent history may have contributed to substantial gene flow. Autosomal SNP data were collated for 438,503 markers from 992 Thai individuals. Using the available self-reported regional origin, four Thai subpopulations genetically distinct from each other and from other Asian populations were resolved by Neighbor-Joining analysis using a 41,569 marker subset. Using an independent Principal Components-based unsupervised clustering approach, four major MSEA subpopulations were resolved in which regional bias was apparent. A major ancestry component was common to these MSEA subpopulations and distinguishes them from other Asian subpopulations. On the other hand, these MSEA subpopulations were admixed with other ancestries, in particular one shared with Chinese. Subpopulation clustering using only Thai individuals and the complete marker set resolved four subpopulations, which are distributed differently across Thailand. A Sino-Thai subpopulation was concentrated in the Central region of Thailand, although this constituted a minority in an otherwise diverse region. Among the most highly differentiated markers which distinguish the Thai subpopulations, several map to regions known to affect phenotypic traits such as skin pigmentation and susceptibility to common diseases. The subpopulation patterns elucidated have important implications for evolutionary and medical genetics. The subpopulation structure within Thailand may reflect the contributions of different migrants throughout the history of MSEA. The information will also be important for genetic association studies to account for population-structure confounding effects.

The association of obesity and coronary artery disease genes with response to SSRIs treatment in major depression

Selective serotonin reuptake inhibitors (SSRIs) are first-line antidepressants for the treatment of major depressive disorder (MDD). However, treatment response during an initial therapeutic trial is often poor and is difficult to predict. Heterogeneity of response to SSRIs in depressed patients is partly driven by co-occurring somatic disorders such as coronary artery disease (CAD) and obesity. CAD and obesity may also be associated with metabolic side effects of SSRIs. In this study, we assessed the association of CAD and obesity with treatment response to SSRIs in patients with MDD using a polygenic score (PGS) approach. Additionally, we performed cross-trait meta-analyses to pinpoint genetic variants underpinnings the relationship of CAD and obesity with SSRIs treatment response. First, PGSs were calculated at different p value thresholds (P_T) for obesity and CAD. Next, binary logistic regression was applied to evaluate the association of the PGSs to SSRIs treatment response in a discovery sample (ISPC, N = 865), and in a replication cohort (STAR*D, N = 1,878). Finally, a cross-trait GWAS meta-analysis was performed by combining summary statistics. We show that the PGSs for CAD and obesity were inversely associated with SSRIs treatment response. At the most significant thresholds, the PGS for CAD and body mass index accounted 1.3%, and 0.8% of the observed variability in treatment response to SSRIs, respectively. In the cross-trait meta-analyses, we identified (1) 14 genetic loci (including NEGR1, CADM2, PMAIP1, PARK2) that are associated with both obesity and SSRIs treatment response; (2) five genetic loci (LINC01412, PHACTR1, CDKN2B, ATXN2, KCNE2) with effects on CAD and SSRIs treatment response. Our findings implicate that the genetic variants of CAD and obesity are linked to SSRIs treatment response in MDD. A better SSRIs treatment response might be achieved through a stratified allocation of treatment for MDD patients with a genetic risk for obesity or CAD.

Contiguous gene syndrome of holoprosencephaly and hypotrichosis simplex: association with an 18p11.3 deletion

We report a patient with a unique combination of features, including microcephaly; mental retardation; poorly developed frontal lobes; hypoplastic pituitary gland; hypothyroidism; alopecia universalis; single maxillary central incisor; taurodontism; median palatal ridge; longitudinally grooved nails; and scoliosis. His unbalanced karyotype was found to be 45,XY,der(15;18)(q10;q10). The constellation of anomalies appears to represent a contiguous gene syndrome caused, at least in part, by deletion of TGIF and the gene responsible for hereditary hypotrichosis simplex. The phenotype of our patient differs other reported patients with del(18p). Possible explanations include (1) the effects of a different deleted region, (2) a positional effect caused by a gene close by, or (3) by interruption of a different gene resulting from chromosomal translocation.

A case with a ring chromosome 13 in a cohort of 203 children with non-syndromic autism and review of the cytogenetic literature

Autistic spectrum disorder (ASD) is a group of neurodevelopmental disorders characterized by impairments of social interaction, communication and restricted, repetitive and stereotyped patterns of behavior, interests and activities. Frequencies of chromosomal abnormalities in cohorts of individuals with ASD varying between 1.2 and 28.6% have been reported. In this study, we evaluated 203 Thai children who met the criteria of the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV), for autistic disorder or pervasive developmental disorder not otherwise specified (PDD-NOS), and who had neither major dysmorphic features nor CGG repeat expansions of the FMR1 gene. A routine G-banding chromosome analysis was performed at a minimum of ISCN 400-550 bands. A chromosomal abnormality was observed in one child (0.5%), a 41-month-old boy with a ring chromosome 13 detected by G-banding analysis and subsequently confirmed by FISH. SNP microarray analysis detected a 2.11-Mb deletion of chromosome 13q34, encompassing 23 genes. The MCF2L and UPF3A genes are among those genes that may explain the autistic features in our case. To the best of our knowledge, only one autistic case with a ring chromosome 13 has been previously reported. In this article, we also systemically reviewed 21 studies that utilized a conventional cytogenetic method to detect chromosomal abnormalities in patients with ASD. When we summed all cases with chromosomal abnormalities, including the case from our study, the frequency of chromosomal abnormalities detected by conventional cytogenetics in patients with ASD was 3.2% (118/3,712).

Effect of the N-terminal sequence on the binding affinity of transthyretin for human retinol-binding protein

During vertebrate evolution, the N-terminal region of transthyretin (TTR) subunit has undergone a change in both length and hydropathy. This was previously shown to change the binding affinity for thyroid hormones (THs). However, it was not known whether this change affects other functions of TTR. In the present study, the effect of these changes on the binding of TTR to retinol-binding protein (RBP) was determined. Two wild-type TTRs from human and Crocodylus porosus, and three chimeric TTRs, including a human chimeric TTR in which its N-terminal sequence was changed to that of C. porosus TTR (croc/huTTR) and two C. porosus chimeric TTRs (hu/crocTTR in which its N-terminal sequence was changed to that of human TTR and xeno/crocTTR in which its N-terminal sequence was changed to that of Xenopus laevis TTR), were analyzed for their binding to human RBP by native-PAGE followed by immunoblotting and a chemilluminescence assay. The K(d) of human TTR was 30.41 ± 2.03 μm, and was similar to that reported for the second binding site, whereas that of crocodile TTR was 2.19 ± 0.24 μm. The binding affinities increased in croc/huTTR (K(d) = 23.57 ± 3.54 μm) and xeno/crocTTR (K(d) = 0.61 ± 0.16 μm) in which their N-termini were longer and more hydrophobic, but decreased in hu/crocTTR (K(d) = 5.03 ± 0.68 μm) in which its N-terminal region was shorter and less hydrophobic. These results suggest an influence of the N-terminal primary structure of TTR on its function as a co-carrier for retinol with RBP.

Bilateral squamosal synostosis: unusual presentation of chromosome 1p12–1p13.3 deletion. Illustrative case

BACKGROUND

Squamosal sutures are minor sutures of the human skull. Early isolated fusion of the sutures (squamosal synostosis) is rarely found.

OBSERVATIONS

The authors report a case of a girl who presented with an abnormal head shape and bilateral squamosal synostosis. Genetic testing revealed a chromosome 1p12–1p13.3 deletion. She has been managed with conservative treatment of the synostosis. She has global developmental delay and multiple anomalies due to the chromosome abnormality.

LESSONS

Isolated squamosal suture synostosis could be an uncommon feature of chromosome 1p12–1p13.3 deletion.

Prenatal exclusion of subtelomeric deletion 1p by fluorescent in situ hybridization

BACKGROUND

Subtelomeric deletion 1p is difficult to detect from banded karyotypes. Recent developments in the field of molecular cytogenetics have made it possible for submicroscopic rearrangements within chromosomes to be detected using fluorescence in situ hybridization (FISH) techniques.

MATERIALS AND METHODS

We describe prenatal FISH testing of subtelomeric 1p deletion in a fetus of a mother whose previous child had subtelomeric 1p deletion.

RESULTS

Fluorescent in situ hybridization from fetal cells demonstrated normal 1p, thus predicting a very high likelihood of an unaffected fetus. The study was confirmed by the birth of a normal neonate.

CONCLUSIONS

We report the use of molecular genetic testing to exclude subtelomeric 1p deletion prenatally. Prenatal diagnostic testing for a known deletion is a reasonable option for couples at risk for having a child with subtelomeric 1p deletion. Molecular testing is more accurate and reliable than ultrasonography and provides families with reassurance.

Characterization of gut microbiota on gender and age groups bias in Thai patients with autism spectrum disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by social communication and interaction problems. The prevalence of ASD is increasing globally, with a higher ratio of males to females. Gastrointestinal symptoms are common in individuals with ASD, and gut microbiota has been implicated in the disorder's development. This study aimed to investigate the gut microbiota alteration in Thai individuals with ASD compared to healthy controls using 16S rRNA gene sequencing. The influence of gender and age on gut microbiota composition and function was also examined. A total of 65 ASD individuals and 30 neurotypical (NT) individuals were included in the analysis. The results revealed notable differences in gut microbiota composition between the ASD and NT groups, with variations observed in microbial richness and the presence of enriched microbial taxa. These differences were influenced by both gender and age. Fusobacteriota, Fusobacteriaceae, and Fusobacterium were found to be enriched in individuals with ASD. Furthermore, the study identified gender-related taxa, such as Bacteroides plebeius, enriched in ASD females. Age-related taxa, including Veillonella, known to be associated with poor oral hygiene, were also observed in ASD children. The analysis of differentially abundant pathways highlighted the enrichment of various metabolic pathways in individuals with ASD, including those related to endocrine-disrupting chemicals. These findings underscore the importance of considering gender and age when studying gut microbiota in ASD. They provide valuable insights into the potential role of gut microbiota dysbiosis in ASD pathogenesis and highlight the influence of environmental factors.