Deletion of Trps1 regulatory elements recapitulates postnatal hip joint abnormalities and growth retardation of Trichorhinophalangeal syndrome in mice.

Trichorhinophalangeal syndrome (TRPS) is a genetic disorder caused by point mutations or deletions in the gene-encoding transcription factor TRPS1. TRPS patients display a range of skeletal dysplasias, including reduced jaw size, short stature, and a cone-shaped digit epiphysis. Certain TRPS patients experience early onset coxarthrosis that leads to a devastating drop in their daily activities. The etiologies of congenital skeletal abnormalities of TRPS were revealed through the analysis of Trps1 mutant mouse strains. However, early postnatal lethality in Trps1 knockout mice has hampered the study of postnatal TRPS pathology. Here, through epigenomic analysis we identified two previously uncharacterized candidate gene regulatory regions in the first intron of Trps1. We deleted these regions, either individually or simultaneously, and examined their effects on skeletal morphogenesis. Animals that were deleted individually for either region displayed only modest phenotypes. In contrast, the Trps1Δint/Δint mouse strain with simultaneous deletion of both genomic regions exhibit postnatal growth retardation. This strain displayed delayed secondary ossification center formation in the long bones and misshaped hip joint development that resulted in acetabular dysplasia. Reducing one allele of the Trps1 gene in Trps1Δint mice resulted in medial patellar dislocation that has been observed in some patients with TRPS. Our novel Trps1 hypomorphic strain recapitulates many postnatal pathologies observed in human TRPS patients, thus positioning this strain as a useful animal model to study postnatal TRPS pathogenesis. Our observations also suggest that Trps1 gene expression is regulated through several regulatory elements, thus guaranteeing robust expression maintenance in skeletal cells.

Minimal Critical Region and Genes for a Typical Presentation of Langer-Giedion Syndrome.

Langer-Giedion syndrome (LGS) is caused by a contiguous deletion at 8q23q24, characterized by exostoses, facial, ectodermal, and skeletal anomalies, and, occasionally, intellectual disability. LGS patients have been diagnosed clinically or by routine cytogenetic techniques, hampering the definition of an accurate genotype-phenotype correlation for the syndrome. We report two unrelated patients with 8q23q24 deletions, characterized by cytogenomic techniques, with one of them, to our knowledge, carrying the smallest deletion reported in classic LGS cases. We assessed the pathogenicity of the deletion of genes within the 8q23q24 region and reviewed other molecularly confirmed cases from the literature. Our findings suggest a 3.2-Mb critical region for a typical presentation of the syndrome, emphasizing the contribution of the TRPS1, RAD21, and EXT1 genes' haploinsufficiency, and facial dysmorphisms as well as bone anomalies as the most frequent features among patients with LGS. We also suggest a possible role for the CSMD3 gene, whose deletion seems to contribute to central nervous system anomalies. Since studies performing such correlation for LGS patients are limited, our data contribute to improving the ge-notype-phenotype characterization for LGS patients.

Trichorhinophalangeal syndrome type II associated with aplasia cutis congenita in a neonate.

Aplasia cutis congenita (ACC) was diagnosed in a newborn with dysmorphic facial features, oligodactyly of the bilateral feet, and hip instability. The neonate's clinical abnormalities in addition to genetic testing confirmed a diagnosis of trichorhinophalangeal syndrome (TRPS) type II. The possibility of concurrent Adams-Oliver syndrome (AOS) is raised.

Dual molecular diagnosis of tricho-rhino-phalangeal syndrome type I and Okur-Chung neurodevelopmental syndrome in one Chinese patient: a case report.

BACKGROUND: Okur-Chung neurodevelopmental syndrome (OCNDS) and tricho-rhino-phalangeal syndrome type I (TRPSI) are rare Mendelian diseases. OCNDS is caused by CSNK2A1 gene variants and TRPSI is caused by the TRPS1gene. However, to have two Mendelian diseases in one patient is even rarer. CASE PRESENTATION: A 6-year-10-month-old boy characterized by special facial features, short stature and mental retardation was referred to our pediatric endocrinology department. Whole-exome sequencing (WES) was done to detect the molecular basis of his disease. This patient was confirmed to carry two variants in the CSNK2A1 gene and one in the TRPS1 gene. The variant in the CSNK2A1 gene was vertically transmitted from his father, and the variant in TRPS1 gene from his mother. These two variants are classified as pathogenic and the causes of the presentation in this child. This patient's father and mother have subsequently been diagnosed as having OCNDS and TRPSI respectively. CONCLUSION: This is the first reported case of a dual molecular diagnosis of tricho-rhino-phalangeal syndrome type I and Okur-Chung neurodevelopmental syndrome in the same patient. This patient is the first published example of vertical transmission of this recurrent CSN2A1 variant from parent to child. A novel variant in the TRPS1 gene that is pathogenic was also identified. In conclusion, identification of the variants in this patient expands the phenotypes and molecular basis of dual Mendelian diseases.

Long-read DNA sequencing fully characterized chromothripsis in a patient with Langer-Giedion syndrome and Cornelia de Lange syndrome-4.

Chromothripsis is a type of chaotic complex genomic rearrangement caused by a single event of chromosomal shattering and repair processes. Chromothripsis is known to cause rare congenital diseases when it occurs in germline cells, however, current genome analysis technologies have difficulty in detecting and deciphering chromothripsis. It is possible that this type of complex rearrangement may be overlooked in rare-disease patients whose genetic diagnosis is unsolved. We applied long read nanopore sequencing and our recently developed analysis pipeline dnarrange to a patient who has a reciprocal chromosomal translocation t(8;18)(q22;q21) as a result of chromothripsis between the two chromosomes, and fully characterize the complex rearrangements at the translocation site. The patient genome was evidently shattered into 19 fragments, and rejoined into derivative chromosomes in a random order and orientation. The reconstructed patient genome indicates loss of five genomic regions, which all overlap with microarray-detected copy number losses. We found that two disease-related genes RAD21 and EXT1 were lost by chromothripsis. These two genes could fully explain the disease phenotype with facial dysmorphisms and bone abnormality, which is likely a contiguous gene syndrome, Cornelia de Lange syndrome type IV (CdLs-4) and atypical Langer-Giedion syndrome (LGS), also known as trichorhinophalangeal syndrome type II (TRPSII). This provides evidence that our approach based on long read sequencing can fully characterize chromothripsis in a patient's genome, which is important for understanding the phenotype of disease caused by complex genomic rearrangement.

Trps1 transcription factor regulates mineralization of dental tissues and proliferation of tooth organ cells.

Mutations of the TRPS1 gene cause trichorhinophalangeal syndrome (TRPS), a skeletal dysplasia with dental abnormalities. TRPS dental phenotypes suggest that TRPS1 regulates multiple aspects of odontogenesis, including the tooth number and size. Previous studies delineating Trps1 expression throughout embryonic tooth development in mice detected strong Trps1 expression in dental mesenchyme, preodontoblasts, and dental follicles, suggesting that TRPS dental phenotypes result from abnormalities in early developmental processes. In this study, Trps1+/- and Trps1-/- mice were analyzed to determine consequences of Trps1 deficiency on odontogenesis. We focused on the aspects of tooth formation that are disturbed in TRPS and on potential molecular abnormalities underlying TRPS dental phenotypes. Microcomputed tomography analyses of molars were used to determine tooth size, crown shape, and mineralization of dental tissues. These analyses uncovered that disruption of one Trps1 allele is sufficient to impair mineralization of dentin in both male and female mice. Enamel mineral density was decreased only in males, while mineralization of the root dental tissues was decreased only in females. In addition, significantly smaller teeth were detected in Trps1+/- females. Histomorphometric analyses of tooth organs showed reduced anterior-posterior diameter in Trps1-/- mice. BrdU-incorporation assay detected reduced proliferation of mesenchymal and epithelial cells in Trps1-/- tooth organs. Immunohistochemistry for Runx2 and Osx osteogenic transcription factors revealed changes in their spatial distribution in Trps1-/- tooth organs and uncovered cell-type specific requirements of Trps1 for Osx expression. In conclusion, this study has demonstrated that Trps1 is a positive regulator of cell proliferation in both dental mesenchyme and epithelium, suggesting that the microdontia in TRPS is likely due to decreased cell proliferation in developing tooth organs. Furthermore, the reduced mineralization observed in Trps1+/- mice may provide some explanation for the extensive dental caries reported in TRPS patients.

[Tricho-rhino-phalangeal syndrome due to a novel frameshift variation of the TRPS1 gene].

OBJECTIVE: To explore the genetic etiology of a pedigree affected with tricho-rhino-phalangeal syndrome. METHODS: Next-generation sequencing (NGS) using a gene panel for hereditary osteopathies was carried out for the proband. Suspected mutation was validated in the proband and her parents by Sanger sequencing. RESULTS: A heterozygous frameshift variation c.1995dupA (p.Gly666Argfs*20) of the TRPS1 gene was detected in the proband but not in her parents. CONCLUSION: The novel c.1995dupA (p.Gly666Argfs*20) mutation of the TRPS1 gene probably underlies the disease in the proband.

Non-ossifying fibroma with a pathologic fracture in a 12-year-old girl with tricho-rhino-phalangeal syndrome: a case report.

BACKGROUND: Tricho-rhino-phalangeal syndrome (TRPS) is a rare autosomal dominant genetic disorder characterized by distinctive craniofacial and skeletal abnormalities, while non-ossifying fibroma (NOF) is a common benign bone tumour in children and adolescents. To date, no case of TRPS coexisting with NOF has been reported. This report presents a 12-year-old girl who had the characteristic features of tricho-rhino-phalangeal syndrome and non-ossifying fibroma with a fibula fracture. CASE PRESENTATION: A 12-year-old girl was admitted to the Department of Endocrinology and Diabetes for evaluation of brachydactyly and a right fibula fracture. Clinical examination revealed sparse scalp hair, a characteristic bulbous pear-shaped nose, and brachydactyly with significant shortening of the fourth metatarsal. Neither intellectual disability nor multiple exostoses were observed. Radiography of both hands showed brachydactyly and cone-shaped epiphyses of the middle phalanges of the digits of both hands with deviation of the phalangeal axis. Genetic analysis of TRPS1 identified a heterozygous germline sequence variant (p.Ala932Thr) in exon 6 in the girl and her father. Approximately 1 month before being admitted to our department, the girl experienced a minor fall and suffered a fracture of the proximal fibula in the right lower limb. The pathological cytological diagnosis of the osteolytic lesion was NOF. Ten months following the surgery, the lesion on the proximal fibula of the girl disappeared. CONCLUSIONS: In conclusion, the present study is the first to report a rare case of NOF with a pathologic fracture in the fibula of a girl with TRPS. The identification of a missense mutation, (p.Ala932Thr), in exon 6 of TRPS1 in this kindred further suggested that the patient had type I TRPS and indicated that mutations in this exon may be correlated with more pronounced features of the syndrome. Radiological techniques and genetic analysis played key roles in the definitive diagnosis.

A novel TRPS1 mutation in a Moroccan family with Tricho-rhino-phalangeal syndrome type III: case report.

BACKGROUND: Tricho-rhino-phalangeal syndrome (TRPS) is an autosomal dominant disorder characterized by craniofacial and skeletal malformations including short stature, thin scalp hair, sparse lateral eyebrows, pear-shaped nose and cone shaped epiphyses. This condition is caused by haploinsufficiency of the TRPS1 gene. Previous genotype-phenotype studies have correlated exon 6 missense mutations with TRPS type III, a severe form of type I with pronounced, facial characteristics, short stature and brachydactyly and differing from type II by the absence of exostoses and mental retardation. CASE PRESENTATION: We report the first case of a Moroccan family, a father and his three children, in which the diagnosis of type III TRPS was suspected based on severe clinical and radiological features. Molecular analysis of the TRPS1 gene revealed a novel missense mutation in exon 6, (p.Ala932Ser), located in the GATA-type DNA-binding zinc finger domain. CONCLUSION: Our observations in this kindred support the previous genotype-phenotype results suggesting that patients with more pronounced facial characteristics and more severe shortening of hands and feet are more likely to have mutation in exon 6 of TRPS1.

Making extra teeth: Lessons from a TRPS1 mutation.

A Thai mother and her two daughters were affected with tricho-rhino-phalangeal syndrome type I. The daughters had 15 and 18 supernumerary teeth, respectively. The mother had normal dentition. Mutation analysis of TRPS1 showed a novel heterozygous c.3809_3811delACTinsCATGTTGTG mutation in all. This mutation is predicted to cause amino acid changes in the Ikaros-like zinc finger domain near the C-terminal end of TRPS1, which is important for repressive protein function. The results of our study and the comprehensive review of the literature show that pathways of forming supernumerary teeth appear to involve APC and RUNX2, the genes responsible for familial adenomatous polyposis syndrome and cleidocranial dysplasia, respectively. The final pathway resulting in supernumerary teeth seems to involve Wnt, a morphogen active during many stages of development. © 2016 Wiley Periodicals, Inc.

Fate mapping of Trps1 daughter cells during cardiac development using novel Trps1-Cre mice.

Tricho-rhino-phalangeal syndrome (TRPS) is a rare congenital disorder that is characterized by abnormal hair growth and skeletal deformities. These result in sparse hair, short stature, and early onset of joint problems. Recent reports have shown that a relatively high proportion of patients with TRPS exhibit a broad range of congenital heart defects. To determine the regulation of Trps1 transcription in vivo, we generated novel transgenic mice, which expressed Cre recombinase under the murine Trps1 proximal promoter sequence (Trps1-Cre). We crossed these mice with Cre reporter mice to identify Trps1 daughter cells. Labeled cells were observed in the appendicular joint tissue, dermal papilla of the hair follicles, cardiac valves, aortic sinus, atrial walls, and the interventricular septum. In situ analysis showed restricted Trps1 expression, which was observed in endocardial cushions of the outflow tract, and in leaflets of all mature cardiac valves. These results suggest that the Trps1 proximal promoter sequence contains some of the tissue-specific Trps1 regulatory region. Further, our findings partially explain why patients with TRPS show a broad range of congenital cardiac defects, although Trps1 expression is observed in a more restricted fashion. genesis 54:379-388, 2016. © 2016 Wiley Periodicals, Inc.

Syndrome disintegration: Exome sequencing reveals that Fitzsimmons syndrome is a co-occurrence of multiple events.

In 1987 Fitzsimmons and Guilbert described identical male twins with progressive spastic paraplegia, brachydactyly with cone shaped epiphyses, short stature, dysarthria, and "low-normal" intelligence. In subsequent years, four other patients, including one set of female identical twins, a single female child, and a single male individual were described with the same features, and the eponym Fitzsimmons syndrome was adopted (OMIM #270710). We performed exome analysis of the patient described in 2009, and one of the original twins from 1987, the only patients available from the literature. No single genetic etiology exists that explains Fitzsimmons syndrome; however, multiple different genetic causes were identified. Specifically, the twins described by Fitzsimmons had heterozygous mutations in the SACS gene, the gene responsible for autosomal recessive spastic ataxia of Charlevoix Saguenay (ARSACS), as well as a heterozygous mutation in the TRPS1, the gene responsible in Trichorhinophalangeal syndrome type 1 (TRPS1 type 1) which includes brachydactyly as a feature. A TBL1XR1 mutation was identified in the patient described in 2009 as contributing to his cognitive impairment and autistic features with no genetic cause identified for his spasticity or brachydactyly. The findings show that these individuals have multiple different etiologies giving rise to a similar phenotype, and that "Fitzsimmons syndrome" is in fact not one single syndrome. Over time, we anticipate that continued careful phenotyping with concomitant genome-wide analysis will continue to identify the causes of many rare syndromes, but it will also highlight that previously delineated clinical entities are, in fact, not syndromes at all. © 2016 Wiley Periodicals, Inc.

Trps1 deficiency inhibits the morphogenesis of secondary hair follicles via decreased Noggin expression.

A representative phenotype of patients with tricho-rhino-phalangeal syndrome (TRPS) is sparse hair. To understand the developmental defects of these patient's hair follicles, we analyzed the development of hair follicles histologically and biochemically using Trps1 deficient (KO) mice. First, we compared the numbers of primary hair follicles in wild-type (WT) and KO embryos at different developmental stages. No differences were observed in the E14.5 skins of WT and KO mice. However, at later time points, KO fetal skin failed to properly develop secondary hair follicles, and the number of secondary hair follicles present in E18.5 KO skin was approximately half compared to that of WT skin. Sonic hedgehog expression was significantly decreased in E17.5 KO skin, whereas no changes were observed in Eda/Edar expression in E14.5 or E17.5 skins. In addition, Noggin expression was significantly decreased in E14.5 and E17.5 KO skin compared to WT skin. In parallel with the suppression of Noggin expression, BMP signaling was promoted in the epidermal cells of KO skins compared to WT skins as determined by immunohistochemistry for phosphorylated Smad1/5/8. The reduced number of secondary hair follicles was restored in skin graft cultures treated with a Noggin and BMP inhibitor. Furthermore, decreased cell proliferation, and increased apoptosis in KO skin was rescued by Noggin treatment. Taken together, we conclude that hair follicle development in Trps1 KO embryos is impaired directly or indirectly by decreased Noggin expression.

Cornelia de Lange syndrome caused by heterozygous deletions of chromosome 8q24: comments on the article by Pereza et al. [2012].

In the March issue of the Journal in 2012, we reported on a girl with Langer-Giedion syndrome (LGS) phenotype and a 7.5 Mb interstitial deletion at 8q23.3q24.13, encompassing the EXT1, but not the TRPS1 gene. Recent discoveries have shown that heterozygous intragenic mutations or contiguous gene deletions including the RAD21 gene, which is located downstream of the TRPS1 gene, are the cause of Cornelia de Lange syndrome-4. Considering that the interstitial deletion in our patient included the RAD21 and 30 other RefSeq genes, we would like to suggest a revision of the diagnosis reported in our previous paper and compare our patient to other reported patients with Cornelia de Lange syndrome-4 caused by heterozygous deletions of chromosome 8q24. © 2015 Wiley Periodicals, Inc.

Langer-Giedion syndrome associated with congenital dural arterio-venous fistula.

Langer-Giedion syndrome (LGS) is a rare disease caused by deletion of chromosome 8q23.3-q24.11. Clinical manifestations include among others multiple exostoses, short stature, intellectual disability, and typical facial dysmorphism. Dural arterio-venous shunts (DAVS) in the pediatric age are rare lesions, which have been classified into three types: dural sinus malformations (DSM), infantile type DAVS (IDAVS), and adult type DAVS (ADAVS). We report a case of a patient with a known LGS who was diagnosed with complex intracranial dural AV fistula at the age of 20. An association between LGS and intracranial dural AV fistulas has to our knowledge never been reported before.

Trichorhinophalangeal syndrome type I: a novel mutation and Perthes-like changes of the hip in a family with 4 cases over 3 generations.

The trichorhinophalangeal syndrome is a rare genetic syndrome with characteristic craniofacial and skeletal abnormalities including hip pathology in variable manifestation. We describe hip involvement with Perthes-like changes and a novel mutation of the TRPSI gene in a family with 4 affected individuals. This case series underlines the clinical significance of rare genetic disorders such as TRPS that among other differential diagnoses should be kept in mind when children present with Perthes-like changes of the hip joint.

Should Patients with Trichorhinophalangeal Syndrome be Tested for Growth Hormone Deficiency?

Type 1 Trichorhinophalangeal syndrome (TRPS) is characterized by typical facial and skeletal abnormalities. These patients frequently exhibit short stature; however, only one case with growth hormone (GH) deficiency can be found in the literature. Our patient is a 10-year-old girl with two novel nonsense pathogenic mutations in the TRPS1 gene, both in heterozygosity: c. 1198C>T (p. Gln400X) and c.2086C>T (p. Arg696X). She has an additional GH deficiency. The patient is short in stature, with a growth velocity of 1.5 cm per year (SDS - 4.07), a bone age of 4.5 years, and she shows no response to the GH stimulation tests. According to a previous report of an identical case, catch-up growth will occur after beginning GH treatment. We believe that GH stimulation tests should be performed on patients with TRPS1 exhibiting a growth velocity below the normal range expected for their age and sex. If the result is subnormal, then GH therapy should be attempted.

New case of trichorinophalangeal syndrome-like phenotype with a de novo t(2;8)(p16.1;q23.3) translocation which does not disrupt the TRPS1 gene.

BACKGROUND: Trichorhinophalangeal syndrome (TRPS) is a rare autosomal dominant genetic disorder characterised by distinctive craniofacial and skeletal abnormalities. TRPS is generally associated with mutations in the TRPS1 gene at 8q23.3 or microdeletions of the 8q23.3-q24.11 region. However, three deletions affecting the same chromosome region and a familial translocation t(8;13) co-segregating with TRPS, which do not encompass or disrupt the TRPS1 gene, have been reported. A deregulated expression of TRPS1 has been hypothesised as cause of the TRPS phenotype of these patients. CASE PRESENTATION: We report the clinical and molecular characterisation of a 57-year-old Caucasian woman carrying the t(2;8)(p16.1;q23.3) de novo balanced translocation. The proband presented with peculiar clinical features (severe craniofacial dysmorphism, alopecia universalis, severe scoliosis, mitral valve prolapse, mild mental impairment and normal growth parameters) that partially overlap with TRPS I. Mutational and array CGH analyses ruled out any genetic defect affecting TRPS1 or genomic alteration at the translocation breakpoint or elsewhere in the genome. Breakpoint mapping excluded disruption of TRPS1, and revealed that the chromosome 8q23.3 breakpoint was located within the IVS10 of the long intergenic non-coding RNA LINC00536, at approximately 300 kb from the TRPS1 5' end. Conversely, the 2p16.1 breakpoint mapped within a LINE sequence, in a region that lacks transcriptional regulatory elements. As a result of the translocation, nucleotide base pair additions and deletions were detected at both breakpoint junction fragments, and an evolutionarily conserved VISTA enhancer element from 2p16.1 was relocated at approximately 325 kb from the TRPS1 promoter. CONCLUSIONS: We suggest that the disruption of the genomic architecture of cis regulatory elements downstream the TRPS1 5' region, combined with the translocation of a novel enhancer element nearby TRPS1, might be the pathogenetic mechanism underpinning the proband's phenotype. The clinical and genetic characterisation of the present subject allowed us to make a genetic diagnosis in the context of a known syndrome, contributing to a better comprehension of the complex transcriptional regulation of TRPS1 and TRPS ethiopathogenesis.

Complex chromosomal rearrangements causing Langer-Giedion syndrome atypical phenotype: genotype-phenotype correlation and literature review.

Langer-Giedion syndrome (LGS) is caused by a deletion of chromosome 8q23.3-q24.11. The LGS clinical spectrum includes intellectual disability (ID), short stature, microcephaly, facial dysmorphisms, exostoses. We describe a 4-year-old girl with ID, short stature, microcephaly, distinctive facial phenotype, skeletal signs (exostoses on the left fibula, coccyx agenesis, stubby and dysmorphic sphenoid bone, osteoporosis), central nervous system malformations (hypoplastic and dysmorphic corpus callosum and septum pellucidum), pituitary gland hypoplasia and hyperreninemia. Array-CGH revealed complex chromosomal rearrangements. A diagnosis of LGS was confirmed by the detection of a 8q23.3-q24.1 deletion. Associated chromosomal abnormalities were a 21q22.1 deletion and a balanced reciprocal translocation t(2;11)(p24;p15) de novo, confirmed by FISH analysis. We document the patient's atypical findings, never described in LGS patients, in order to update the genotype-phenotype correlation. We speculate that the disruption of regulatory elements mapping upstream CYP11B2 involved in the deleted region could cause hyperreninemia.