De novo deletion of 1q24.3-q31.2 in a patient with severe growth retardation

Case Report: Candidate Genes Associated With Prenatal Ultrasound Anomalies in a Fetus With Prenatally Detected 1q23.3q31.2 Deletion

Background: Patients with deletions involving the long arm of chromosome 1 are rare, and the main aim of this study was to refine the genotype-phenotype correlation.

Case Report: In this report, a 28-year-old pregnant woman, gravida 2 para 1, at 25⁺⁴ weeks of gestation underwent ultrasound examination in our institute. The ultrasonographic findings of the fetus were as follows: (1) fetal growth restriction; (2) cleft lip and palate; (3) bilateral renal hypoplasia; (4) lateral ventriculomegaly; (5) single umbilical artery; (6) absent stomach; (7) coronary sinus dilatation with persistent left superior vena cava, ventricular septal defect and unroofed coronary sinus syndrome. Chromosomal microarray analysis of amniotic fluid from the fetus revealed a 28.025 Mb deletion in 1q23.3q31.2, spanning from position 164,559,675 to 192,584,768 (hg19).

Conclusion: Genotype-phenotype correlation might improve prenatal diagnosis of fetuses with chromosome 1q deletion. PBX1 could be a candidate gene for fetal growth restriction, renal hypoplasia and congenital heart disease. Fetal growth restriction was accompanied by decreased renal volume in the fetus. Combined with ultrasonic examination, the application of chromosomal microarray analysis will provide accurate prenatal diagnosis.

Delineation of the 1q24.3 microdeletion syndrome provides further evidence for the potential role of non-coding RNAs in regulating the skeletal phenotype

Microdeletions within 1q24 have been associated with growth deficiency, varying intellectual disability, and skeletal abnormalities. The candidate locus responsible for the various phenotypic features of this syndrome has previously been predicted to lie in the area of 1q24.3, but molecular evidence of the causative gene remains elusive. Here, we report two additional patients carrying the smallest reported 1q24 deletion to date. Patient 1 exhibited intrauterine growth retardation, shortening of the long bones, frontal bossing, microstomia, micrognathia, and a language acquisition delay. Her mother, Patient 2, displayed a broad forehead and nasal bridge, thick supraorbital ridges, and toe brachydactyly, along with learning disability and language acquisition delay. The microdeletion encompasses a 94 Kb region containing exon 14 and portions of the surrounding introns of the gene encoding dynamin 3 (DNM3), resulting in an in-frame loss of 38 amino acids. This microdeletion site also contains a long non-coding RNA (DNM3OS) and three microRNAs (miR-214, miR-199A2, and miR-3120). Following culture of patient-derived and control fibroblasts, molecular analyses were performed to determine expression levels of genes affected by the heterozygous deletion. Results show decreased expression of DNM3OS and miR-214-3p in patient fibroblasts cultured in an osteogenic induction medium. Overall, our data provide further evidence to support a functional role for non-coding RNAs in regulating the skeletal phenotype, and the potential of a functionally-impaired DNM3 protein causing the non-skeletal disease pathogenesis.

1q24 deletion syndrome. Two cases and new insights into genotype-phenotype correlations

1q24q25 deletions cause a distinctive phenotype including proportionate short stature, microcephaly, brachydactyly, dysmorphic facial features and intellectual disability. We present a mother and son who have a 672 kb microdeletion at 1q24q25. They have the typical skeletal features previously described but do not have any associated intellectual disability. We compare the genes within our patients' deletion to those in the deletions of previously reported cases. This indicates two genes that may be implicated in the intellectual disability usually associated with this deletion syndrome; PIGC and C1orf105. In addition, our cases provide supporting evidence to recent published work suggesting that the skeletal features may be linked to the microRNAs miR199 and miR214, encoded within intron 14 of the Dynamin-3 gene.

Cryo-EM and X-ray structures of TRPV4 reveal insight into ion permeation and gating mechanisms

The transient receptor potential (TRP) channel TRPV4 participates in multiple biological processes, and numerous TRPV4 mutations underlie several distinct and devastating diseases. Here we present the cryo-EM structure of Xenopus tropicalis TRPV4 at 3.8-Å resolution. The ion-conduction pore contains an intracellular gate formed by the inner helices, but lacks any extracellular gate in the selectivity filter, as observed in other TRPV channels. Anomalous X-ray diffraction analyses identify a single ion-binding site in the selectivity filter, thus explaining TRPV4 nonselectivity. Structural comparisons with other TRP channels and distantly related voltage-gated cation channels reveal an unprecedented, unique packing interface between the voltage-sensor-like domain and the pore domain, suggesting distinct gating mechanisms. Moreover, our structure begins to provide mechanistic insights to the large set of pathogenic mutations, offering potential opportunities for drug development.

MicroRNAs in orthopaedic research: Disease associations, potential therapeutic applications, and perspectives

MicroRNAs (miRNAs) are small non-coding RNAs that function to control many cellular processes by their ability to suppress expression of specific target genes. Tens to hundreds of target genes may be affected by one miRNA, thereby resulting in modulation of multiple pathways in any given cell type. Therefore, altered expression of miRNAs (i.e., during tissue development or in scenarios of disease or cellular stress) can have a profound impact on processes regulating cell differentiation, metabolism, proliferation, or apoptosis, for example. Over the past 5-10 years, thousands of reports have been published on miRNAs in cartilage and bone biology or disease, thus highlighting the significance of these non-coding RNAs in regulating skeletal development and homeostasis. For the purpose of this review, we will focus on miRNAs or miRNA families that have demonstrated function in vivo within the context of cartilage, bone or other orthopaedic-related tissues (excluding muscle). Specifically, we will discuss studies that have utilized miRNA transgenic mouse models or in vivo approaches to target a miRNA with the aim of altering conditions such as osteoarthritis, osteoporosis and bone fractures in rodents. We will not discuss miRNAs in the context skeletal cancers since this topic is worthy of a review of its own. Overall, we aim to provide a comprehensive description of where the field currently stands with respect to the therapeutic potential of specific miRNAs to treat orthopaedic conditions and current technologies to target and modify miRNA function in vivo. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:33-51, 2018.

Nine year old boy with chromosome 1q23.3-q25.1 deletion

Interstitial deletions of the long arm of chromosome 1 are rare, and recent reports of individuals with molecularly characterized deletions have resulted in advances in genotype-phenotype correlation. The recognizable phenotype associated with 1q23.3-q25.1 includes pre- and post-natal growth retardation, microcephaly, intellectual disability, delayed language acquisition, small hands and feet with brachydactyly and single palmar crease, and distinctive facial features including short bulbous nose, micrognathia, and ear malformations. We report a patient with an 11.35 Mb deletion from 1q23.3-q25.1 who has these features in addition to a rarely reported complication-profound sensorineural hearing loss. He has both pre- and post-natal growth deficiency and growth hormone deficiency that was diagnosed at age 2 years. However, unlike other individuals with this deletion and growth hormone deficiency, this boy has responded to treatment with human growth hormone. © 2016 Wiley Periodicals, Inc.

Two further patients with the 1q24 deletion syndrome expand the phenotype: A possible role for the miR199-214 cluster in the skeletal features of the condition

Submicroscopic deletions within chromosome 1q24q25 are associated with a syndromic phenotype of short stature, brachydactyly, learning difficulties, and facial dysmorphism. The critical region for the deletion phenotype has previously been narrowed to a 1.9 Mb segment containing 13 genes. We describe two further patients with 1q24 microdeletions and the skeletal phenotype, the first of whom has normal intellect, whereas the second has only mild learning impairment. The deletion in the first patient is very small and further narrows the critical interval for the striking skeletal aspects of this condition to a region containing only Dynamin 3 (DNM3) and two microRNAs that are harbored within intron 14 of this gene: miR199 and miR214. Mouse studies raise the possibility that these microRNAs may be implicated in the short stature and skeletal abnormalities of this microdeletion condition. The deletion in the second patient spans the previously reported critical region and indicates that the cognitive impairment may not always be as severe as previous reports suggest.

Refinement of genotype-phenotype correlation in 18 patients carrying a 1q24q25 deletion

Interstitial deletion 1q24q25 is a rare rearrangement associated with intellectual disability, growth retardation, abnormal extremities and facial dysmorphism. In this study, we describe the largest series reported to date, including 18 patients (4M/14F) aged from 2 days to 67 years and comprising two familial cases. The patients presented with a characteristic phenotype including mild to moderate intellectual disability (100%), intrauterine (92%) and postnatal (94%) growth retardation, microcephaly (77%), short hands and feet (83%), brachydactyly (70%), fifth finger clinodactyly (78%) and facial dysmorphism with a bulbous nose (72%), abnormal ears (67%) and micrognathia (56%). Other findings were abnormal palate (50%), single transverse palmar crease (53%), renal (38%), cardiac (38%), and genital (23%) malformations. The deletions were characterized by chromosome microarray. They were of different sizes (490 kb to 20.95 Mb) localized within chromosome bands 1q23.3-q31.2 (chr1:160797550-192912120, hg19). The 490 kb deletion is the smallest deletion reported to date associated with this phenotype. We delineated three regions that may contribute to the phenotype: a proximal one (chr1:164,501,003-167,022,133), associated with cardiac and renal anomalies, a distal one (chr1:178,514,910-181,269,712) and an intermediate 490 kb region (chr1:171970575-172460683, hg19), deleted in the most of the patients, and containing DNM3, MIR3120 and MIR214 that may play an important role in the phenotype. However, this genetic region seems complex with multiple regions giving rise to the same phenotype.

Patient-derived skeletal dysplasia induced pluripotent stem cells display abnormal chondrogenic marker expression and regulation by BMP2 and TGFβ1

Skeletal dysplasias (SDs) are caused by abnormal chondrogenesis during cartilage growth plate differentiation. To study early stages of aberrant cartilage formation in vitro, we generated the first induced pluripotent stem cells (iPSCs) from fibroblasts of an SD patient with a lethal form of metatropic dysplasia, caused by a dominant mutation (I604M) in the calcium channel gene TRPV4. When micromasses were grown in chondrogenic differentiation conditions and compared with control iPSCs, mutant TRPV4-iPSCs showed significantly (P<0.05) decreased expression by quantitative real-time polymerase chain reaction of COL2A1 (IIA and IIB forms), SOX9, Aggrecan, COL10A1, and RUNX2, all of which are cartilage growth plate markers. We found that stimulation with BMP2, but not TGFβ1, up-regulated COL2A1 (IIA and IIB) and SOX9 gene expression, only in control iPSCs. COL2A1 (Collagen II) expression data were confirmed at the protein level by western blot and immunofluorescence microscopy. TRPV4-iPSCs showed only focal areas of Alcian blue stain for proteoglycans, while in control iPSCs the stain was seen throughout the micromass sample. Similar staining patterns were found in neonatal cartilage from control and patient samples. We also found that COL1A1 (Collagen I), a marker of osteogenic differentiation, was significantly (P<0.05) up-regulated at the mRNA level in TRPV4-iPSCs when compared with the control, and confirmed at the protein level. Collagen I expression in the TRPV4 model also may correlate with abnormal staining patterns seen in patient tissues. This study demonstrates that an iPSC model can recapitulate normal chondrogenesis and that mutant TRPV4-iPSCs reflect molecular evidence of aberrant chondrogenic developmental processes, which could be used to design therapeutic approaches for disorders of cartilage.

1q25.2-q31.3 Deletion in a female with mental retardation, clinodactyly, minor facial anomalies but no growth retardation

The reports of 1q25-32 deletion cases are rare. We reported here an 11-year-old Chinese Han female with an interstitial 1q25 deletion displaying mental retardation, clinodactyly of the 5th finger and minor facial anomalies. Notably, the patient did not present growth retardation which is quite common in patients with 1q25-32 deletion encompassing LHX4. The heterozygous deletion in this patient was characterized as 46,XX,del(1)(q25.2-q31.3) with a length of 20.5 Mb according to SNP-array test results. STRP (Short Tandem Repeat Polymorphism) analysis of the family trio indicated the genomic abnormality was de novo with paternal origin. After a genotype-phenotype analysis, we proposed here the loss of a 3.1 Mb critical region including 24 genes within 1q25.2 (chr1:174.5-177.6 Mb, build 36) may account for the mental retardation in patients with 1q25-32 deletion.

Diagnosing mucopolysaccharidosis IVA

Mucopolysaccharidosis IVA (MPS IVA; Morquio A syndrome) is an autosomal recessive lysosomal storage disorder resulting from a deficiency of N-acetylgalactosamine-6-sulfate sulfatase (GALNS) activity. Diagnosis can be challenging and requires agreement of clinical, radiographic, and laboratory findings. A group of biochemical genetics laboratory directors and clinicians involved in the diagnosis of MPS IVA, convened by BioMarin Pharmaceutical Inc., met to develop recommendations for diagnosis. The following conclusions were reached. Due to the wide variation and subtleties of radiographic findings, imaging of multiple body regions is recommended. Urinary glycosaminoglycan analysis is particularly problematic for MPS IVA and it is strongly recommended to proceed to enzyme activity testing even if urine appears normal when there is clinical suspicion of MPS IVA. Enzyme activity testing of GALNS is essential in diagnosing MPS IVA. Additional analyses to confirm sample integrity and rule out MPS IVB, multiple sulfatase deficiency, and mucolipidoses types II/III are critical as part of enzyme activity testing. Leukocytes or cultured dermal fibroblasts are strongly recommended for enzyme activity testing to confirm screening results. Molecular testing may also be used to confirm the diagnosis in many patients. However, two known or probable causative mutations may not be identified in all cases of MPS IVA. A diagnostic testing algorithm is presented which attempts to streamline this complex testing process.

Human skeletal dysplasia caused by a constitutive activated transient receptor potential vanilloid 4 (TRPV4) cation channel mutation

The transient receptor potential vanilloid 4 (TRPV4) cation channel, a member of the TRP vanilloid subfamily, is expressed in a broad range of tissues where it participates in the generation of Ca²⁺ signals and/or depolarization of the membrane potential. Regulation of TRPV4 abundance at the cell surface is critical for osmo- and mechanotransduction. Defects in TRPV4 are the cause of several human diseases, including brachyolmia type 3 (MIM:113500) (also known as brachyrachia or spondylometaphyseal dysplasia Kozlowski type [MIM:118452]), and metatropic dysplasia (MIM:156530) (also called metatropic dwarfism or parastremmatic dwarfism [MIM:168400]). These bone dysplasia mutants are characterized by severe dwarfism, kyphoscoliosis, distortion and bowing of the extremities, and contractures of the large joints. These diseases are characterized by a combination of decreased bone density, bowing of the long bones, platyspondyly, and striking irregularities of endochondral ossification with areas of calcific stippling and streaking in radiolucent epiphyses, metaphyses, and apophyses. In this review, we discuss the potential effect of the mutation on the regulation of TRPV4 functions, which are related to human diseases through deviated function. In particular, we emphasize how the constitutive active TRPV4 mutant affects endochondral ossification with a reduced number of hypertrophic chondrocytes and the presence of cartilage islands within the zone of primary mineralization. In addition, we summarize current knowledge about the role of TRPV4 in the pathogenesis of several diseases.

Distinctive phenotype in 9 patients with deletion of chromosome 1q24-q25

Reports of individuals with deletions of 1q24→q25 share common features of prenatal onset growth deficiency, microcephaly, small hands and feet, dysmorphic face and severe cognitive deficits. We report nine individuals with 1q24q25 deletions, who show distinctive features of a clinically recognizable 1q24q25 microdeletion syndrome: prenatal-onset microcephaly and proportionate growth deficiency, severe cognitive disability, small hands and feet with distinctive brachydactyly, single transverse palmar flexion creases, fifth finger clinodactyly and distinctive facial features: upper eyelid fullness, small ears, short nose with bulbous nasal tip, tented upper lip, and micrognathia. Radiographs demonstrate disharmonic osseous maturation with markedly delayed bone age. Occasional features include cleft lip and/or palate, cryptorchidism, brain and spinal cord defects, and seizures. Using oligonucleotide-based array comparative genomic hybridization, we defined the critical deletion region as 1.9 Mb at 1q24.3q25.1 (chr1: 170,135,865-172,099,327, hg18 coordinates), containing 13 genes and including CENPL, which encodes centromeric protein L, a protein essential for proper kinetochore function and mitotic progression. The growth deficiency in this syndrome is similar to what is seen in other types of primordial short stature with microcephaly, such as Majewski osteodysplastic primordial dwarfism, type II (MOPD2) and Seckel syndrome, which result from loss-of-function mutations in genes coding for centrosomal proteins. DNM3 is also in the deleted region and expressed in the brain, where it participates in the Shank-Homer complex and increases synaptic strength. Therefore, DNM3 is a candidate for the cognitive disability, and CENPL is a candidate for growth deficiency in this 1q24q25 microdeletion syndrome.