Explore the vast range of titles available.

Background/Objectives: Severe neurodevelopmental disorders caused by homozygous ASTN1 variants have recently been reported. The aim of this study is to present the expanded phenotype and prognostic findings through a longitudinal follow-up of a patient with a homozygous ASTN1 variant. Methods: We conducted a 15-year clinical evaluation of a girl who initially presented at 10 years of age. The genetic etiology was investigated using exome sequencing. Results: The patient had a profound intellectual disability, severe expressive language delay, and infantile-onset epilepsy. She also had microcephaly, achieved independent walking at age 7 and had speech limited to only two words at admission. A novel homozygous frameshift variant, c.2096del (p.Cys699Serfs*22), in ASTN1 was identified. Over the follow-up period, her postnatal microcephaly became more pronounced, and she experienced a late relapse into generalized tonic–clonic seizures after a decade-long remission. She remains entirely dependent on caregivers for basic self-care at age 25. Conclusions: ASTN1-related phenotype is associated with a severe neurodevelopmental disease, and the late relapse of seizures after prolonged remission highlights the need for lifelong neurological monitoring and multidisciplinary care.

Motile and non-motile cilia play critical roles in mammalian development and health. These organelles are composed of a 1000 or more unique proteins, but their assembly depends entirely on proteins synthesized in the cell body and transported into the cilium by intraflagellar transport (IFT). In mammals, malfunction of non-motile cilia due to IFT dysfunction results in complex developmental phenotypes that affect most organs. In contrast, disruption of motile cilia function causes subfertility, disruption of the left-right body axis, and recurrent airway infections with progressive lung damage. In this work, we characterize allele specific phenotypes resulting from IFT74 dysfunction in human and mice. We identified two families carrying a deletion encompassing IFT74 exon 2, the first coding exon, resulting in a protein lacking the first 40 amino acids and two individuals carrying biallelic splice site mutations. Homozygous exon 2 deletion cases presented a ciliary chondrodysplasia with narrow thorax and progressive growth retardation along with a mucociliary clearance disorder phenotype with severely shorted cilia. Splice site variants resulted in a lethal skeletal chondrodysplasia phenotype. In mice, removal of the first 40 amino acids likewise results in a motile cilia phenotype but with little effect on primary cilia structure. Mice carrying this allele are born alive but are growth restricted and developed hydrocephaly in the first month of life. In contrast, a strong, likely null, allele of Ift74 in mouse completely blocks ciliary assembly and causes severe heart defects and midgestational lethality. In vitro studies suggest that the first 40 amino acids of IFT74 are dispensable for binding of other IFT subunits but are important for tubulin binding. Higher demands on tubulin transport in motile cilia compared to primary cilia resulting from increased mechanical stress and repair needs could account for the motile cilia phenotype observed in human and mice.

Osteogenesis imperfecta type XI (OI-XI) and Bruck syndrome type I (BS1) are two rare disorders caused by biallelic variants in the FKBP10, characterized by early-onset bone fractures and progressive skeletal deformities. The patients with OI-XI, also co-segregated with autosomal-recessive epidermolysis bullosa simplex caused by KRT14 variant, have been reported. In this study, the follow-up clinical features of the patients with OI-XI and BS1 phenotypes due to biallelic FKBP10 variants are compared. The aim of this study is to investigate the follow-up findings of OI-XI and BS1 phenotypes in patients with the FKBP10 variants. A total of 19 children, ten males and nine females, from 16 unrelated families were included in the study. FKBP10 variants were investigated by next-generation sequencing (NGS) based panel gene test or Sanger sequencing. Seventeen patients were followed between 1.5 and 16.8 years, and the last follow-up age was between 2 and 24.6 years (median 10.7 years). They received intravenous bisphosphonate infusions once every 3 months in follow-up period. We identified four different biallelic FKBP10 variants, two of which are novel (c.890_897dup TGATGGAC, p.Gly300Ter and c.1256 + 1G > A) in 16 families. Five of these patients also had findings of epidermolysis bullosa simplex, and the same biallelic c.612T > A (p.Tyr204Ter) variant in KRT14, as well as FKBP10, were identified. Twelve patients were diagnosed with OI-XI; whereas, seven were diagnosed with BS1. The BS1 phenotype was late-onset and the annual fracture number was lower. After bisphosphonate treatment, bone mineral densitometry Z score at L1–L4 increased (p = 0.005) and the number of annual fractures decreased (p = 0.036) in patients with OI-XI. However, no significant effect of bisphosphonate treatment was found on these values in BS1 patients. Despite the treatment, the rate of scoliosis and long bone deformity had increased in both groups at the last examination; and, only two patients could take a few steps with the aid of a walker, while others were not ambulatory, and they used wheelchairs for mobility. We identified two novel variants in FKBP10. Families originating from the same geographic region and having the same variant suggest founder effects. Although the number of fractures decreased with bisphosphonate treatment, none of our patients were able to walk during the follow-up. This study is valuable in terms of showing the follow-up findings of patients with FKBP10 variants for the first time.

Skeletal dysplasia with multiple dislocations are severe disorders characterized by dislocations of large joints and short stature. The majority of them have been linked to pathogenic variants in genes encoding glycosyltransferases, sulfotransferases or epimerases required for glycosaminoglycan synthesis. Using exome sequencing, we identify homozygous mutations in SLC10A7 in six individuals with skeletal dysplasia with multiple dislocations and amelogenesis imperfecta. SLC10A7 encodes a 10-transmembrane-domain transporter located at the plasma membrane. Functional studies in vitro demonstrate that SLC10A7 mutations reduce SLC10A7 protein expression. We generate a Slc10a7 −/− mouse model, which displays shortened long bones, growth plate disorganization and tooth enamel anomalies, recapitulating the human phenotype. Furthermore, we identify decreased heparan sulfate levels in Slc10a7 −/− mouse cartilage and patient fibroblasts. Finally, we find an abnormal N -glycoprotein electrophoretic profile in patient blood samples. Together, our findings support the involvement of SLC10A7 in glycosaminoglycan synthesis and specifically in skeletal development. The majority of skeletal dysplasia are caused by pathogenic variants in genes required for glycosaminoglycan (GAG) metabolism. Here, Dubail et al. identify genetic variants in the solute carrier family protein SLC10A7 in families with skeletal dysplasia and amelogenesis imperfecta that disrupt GAG synthesis.

Background/Objectives: Multiple epiphyseal dysplasia (MED) is a clinically and genetically heterogeneous group of disorders characterized by a waddling gait, joint pain, and early-onset osteoarthritis. The aim of this study was to compare the genetic characteristics and long-term clinical follow-up findings of 22 patients with MED from 17 unrelated families. Methods: Molecular diagnosis was performed using clinical exome analysis and exome sequencing. Seventeen children were followed for a median of 5.5 years. Results: Eighteen disease-related variants were identified: 47% in COMP, 11.8% each in COL9A2 and COL9A3 in a monoallelic state, 17.6% in SLC26A2, and 11.8% each in MATN3 and CANT1 in a biallelic state. Some COMP mutations previously identified in pseudoachondroplasia, an allelic disorder of MED1, were shown in our study to exhibit a typical MED1 or intermediate phenotype. In contrast, it was confirmed that certain mutations in SLC26A2 lead to MED4 phenotype. Furthermore, it has been observed that biallelic variants in MATN3 may be associated with the MED5 phenotype. In patients with MED2 and MED3, the knee joint is affected, while in other types, the hip joint is predominantly affected. In 15 children followed until ages 11–18, height decreased slightly as they grew older but remained normal or at the lower limit, and slow progression was observed in the waddling gait and joint pain, except in the intermediate form. Conclusions: This study reveals the frequency of disease-related variants, including seven novel ones, in genes leading to MED1–5 and 7 phenotypes, and expands the spectrum of genetic and clinical phenotypes.

Osteosclerotic bone diseases include more than 30 rare diseases characterized by excessive bone formation. The aim of this study is to compare the molecular pathogenesis and prognostic features of 12 different osteosclerotic diseases. Thirty-four patients from 23 families were included, 25 of whom were followed for a period of one to 22 years. Exome sequencing was performed in 20 families. Primary hypertrophic osteoarthropathy (PHOAR1/2) was found in 12 patients, followed by juvenile Paget’s disease (JPD)-5 in five, craniometaphyseal dysplasia (CMD) and Camurati-Engelmann disease (CED) in four, Ghosal hematodiaphyseal dysplasia (GHDD) in three patients, sclerosteosis-1 in two patients, and ultra-rare diseases including trichothiodystrophy-1, prenatal Caffey disease, melorheosteosis, and Lenz-Majewski hyperostotic dwarfism in one patient each. Patients with CMD and sclerosteosis-1 had severe cranial sclerosis leading to facial dysmorphism. CMD was characterized by metaphyseal widening, radiolucency, and diaphyseal sclerosis of the long bones in early childhood and later developed Erlenmeyer flask deformity sparing the vertebrae and pelvis, whereas sclerosteosis-1 manifested as generalized sclerosis. CED and GHDD share bone pain, difficulty in walking, and diaphyseal sclerosis, with some patients also having bone marrow involvement. Interestingly, patients with CED and JPD-5 showed osteopenia in early childhood, followed by the development of osteosclerosis in late childhood. Clinical and radiologic findings improved over time in PHOAR1 patients, whereas they progressed in JPD-5 and trichothiodystrophy-1 patients. Intra- and interfamilial clinical differences were observed in CMD, CED, JPD-5, and GHDD. The knowledge gained about the natural history of osteosclerotic diseases will make an important contribution to their diagnosis and management.

Gene linked to brain malformation The identification of genetic loci linked to abnormal cortical development is complicated by genetic heterogeneity, small family sizes and diagnostic classifications that do not reflect molecular pathogenesis. These obstacles have been overcome in a study using whole-exome sequencing. Recessive mutations in the WD repeat domain 62 ( WDR62 ) gene are shown to cause a wide spectrum of seemingly disparate brain abnormalities, including microcephaly, pachygyria and, in one instance, cerebellar hypoplasia. Unlike other known microcephaly genes, WDR62 does not associate with centrosomes; it is predominantly nuclear in localization and is expressed transiently in the neocortex during embryonic neurogenesis. Mapping disease loci that underlie putative Mendelian forms of malformations of cortical development is complicated by genetic heterogeneity, small family sizes and diagnostic classifications that may not reflect molecular pathogenesis. These authors use whole-exome sequencing to identify recessive mutations in WDR62 as the cause of a wide spectrum of severe cerebral cortical malformations. WDR62 's nuclear localization to germinal neuroepithelia indicates that cortical malformations can be caused by events during progenitor proliferation and neurogenesis. The development of the human cerebral cortex is an orchestrated process involving the generation of neural progenitors in the periventricular germinal zones, cell proliferation characterized by symmetric and asymmetric mitoses, followed by migration of post-mitotic neurons to their final destinations in six highly ordered, functionally specialized layers 1 , 2 . An understanding of the molecular mechanisms guiding these intricate processes is in its infancy, substantially driven by the discovery of rare mutations that cause malformations of cortical development 3 , 4 , 5 , 6 . Mapping of disease loci in putative Mendelian forms of malformations of cortical development has been hindered by marked locus heterogeneity, small kindred sizes and diagnostic classifications that may not reflect molecular pathogenesis. Here we demonstrate the use of whole-exome sequencing to overcome these obstacles by identifying recessive mutations in WD repeat domain 62 ( WDR62 ) as the cause of a wide spectrum of severe cerebral cortical malformations including microcephaly, pachygyria with cortical thickening as well as hypoplasia of the corpus callosum. Some patients with mutations in WDR62 had evidence of additional abnormalities including lissencephaly, schizencephaly, polymicrogyria and, in one instance, cerebellar hypoplasia, all traits traditionally regarded as distinct entities. In mice and humans, WDR62 transcripts and protein are enriched in neural progenitors within the ventricular and subventricular zones. Expression of WDR62 in the neocortex is transient, spanning the period of embryonic neurogenesis. Unlike other known microcephaly genes, WDR62 does not apparently associate with centrosomes and is predominantly nuclear in localization. These findings unify previously disparate aspects of cerebral cortical development and highlight the use of whole-exome sequencing to identify disease loci in settings in which traditional methods have proved challenging.

Background Heterozygous TRPV4 mutations cause a group of skeletal dysplasias characterized by short stature, short trunk, and skeletal deformities. Objective The aim of this study is to compare the natural history of clinical and radiologic features of patients with different TRPV4 -related skeletal dysplasias. Materials and methods Thirteen patients with a mutation in TRPV4 were included in the study, and 11 were followed for a median of 6.5 years. The clinical phenotype of five patients was compatible with spondylometaphyseal dysplasia Kozlowski type, three each with metatropic dysplasia and brachyolmia type 3, and one each with spondyloepiphyseal dysplasia Maroteaux type and congenital distal spinal muscular atrophy. Results Short stature and bone pain when running, walking, and climbing stairs occurred in patients with spondylometaphyseal dysplasia Kozlowski type and metatropic dysplasia from the age of 5 years and worsened with increasing age. Kyphosis was more pronounced with increasing age in these two groups of patients, while severe scoliosis occurred in brachyolmia type 3. In the radiographs of patients with spondylometaphyseal dysplasia Kozlowski type and metatropic dysplasia, severe platyspondyly persisted into adulthood or puberty. The patients with spondylometaphyseal dysplasia Kozlowski type exhibited irregular proximal femora leading to destruction of the femoral head towards the end of puberty, whereas metatropic dysplasia showed marked irregularity and widening of the femoral neck. We also observed that metaphyseal dysplasia in long bones other than the proximal femur was so inconspicuous that it could be ignored in patients with spondylometaphyseal dysplasia Kozlowski type. Conclusion Comparison of radiologic features that change with age in five different TRPV4 -related skeletal dysplasias will be of great benefit in the management of this patient group. Graphical Abstract

Background. 19p13.3 microduplication syndrome is a newly defined intrauterine onset growth retardation syndrome characterized by microcephaly, moderate intellectual disability, speech delay, and mild dysmorphic features. The PIAS4 gene located in this region plays a crucial role as a transcriptional co-regulator in various cellular pathways including STAT, p53/TP53 and growth hormone (GH) signaling and mutations in this gene are thought to be responsible for clinical features. Case. We present a 10 year-old girl with intrauterine onset growth retardation, microcephaly, and mild facial dysmorphic features. Treatment with GH was started at 4 years and 9 months of age targeting the severe short stature (-3.65 standard deviation score, SDS) since she had significant IGF-1 response to exogenous GH. Microarray study demonstrated a 19p13.3 microduplication of 4.4 Mb. FISH analyses revealed mosaic extra signals (27.5% on blood lymphocytes, and 47% on buccal epithelium) of 19p13.3 region. At the age of 10, her height was at -2.37 SDS, and she had mild intellectual disability which has been described in 19p13.3 microduplication syndrome. Conclusion. We present here a patient with typical findings of 19p13.3 microduplication syndrome and also with a prominent response to GH treatment, which has not been reported previously in this syndrome.

Cardiofaciocutaneous syndrome (CFCS) is a rare syndromic disorder caused by germline mutations affecting the RAS/MAPK pathway. It is characterized by distinctive craniofacial dysmorphism, congenital heart defects, skin abnormalities, gastrointestinal dysfunction, neurocognitive impairment, and epilepsy. Emerging evidence suggests an association with hypogammaglobulinemia, but a comprehensive characterization of immunological abnormalities in CFCS is lacking. We conducted a retrospective, multicenter observational study to investigate the immunological phenotype of CFCS. Clinical features, immune-related manifestations, and laboratory parameters were analyzed to delineate the immunological profile of affected individuals. A total of 56 patients with a confirmed clinical and molecular diagnosis of CFCS were included, with a median age at evaluation of 13 years (range: 1-39 years). Increased susceptibility to infections was reported in 18/56 patients (32%), while autoimmune manifestations were observed in 14/56 patients (25%). Common immunological findings included monocytosis (32%), lymphopenia (21%), and hypogammaglobulinemia, with decreased IgG, IgA, or IgM levels in 21%, 40%, and 35% of patients, respectively. Genotype-phenotype analysis revealed that mutations were predominantly associated with T-cell lymphopenia, whereas mutations were linked to monocytosis, reduced naïve and switched-memory B cells, and hypogammaglobulinemia. Immunodeficiency-related treatments, including immunoglobulin replacement therapy, antibiotic prophylaxis, or immunosuppressive therapy, were administered to 6/56 patients (11%). CFCS is associated with recurrent yet heterogeneous immunological abnormalities, including lymphopenia, hypogammaglobulinemia, and increased infection susceptibility. Given these findings, routine immunological assessment should be considered in CFCS patients to facilitate early detection and appropriate management of immune dysfunction.