Project description: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.
Project description:The Langer-Giedion syndrome (LGS), which is characterized by craniofacial dysmorphism and skeletal abnormalities, is caused by a genetic defect in 8q24.1. We have used 13 anonymous DNA markers from an 8q24.1-specific microdissection library, as well as c-myc and thyroglobulin gene probes, to map the deletion breakpoints in 16 patients with LGS. Twelve patients had a cytogenetically visible deletion, two patients had an apparently balanced translocation, and two patients had an apparently normal karyotype. In all cases except one translocation patient, loss of genetic material was detected. The DNA markers fall into 10 deletion intervals. Clone L48 (D8S51) defines the shortest region of deletion overlap (SRO), which is estimated to be less than 2 Mbp. Three clones--p17-2.3 EE (D8S43), L24 (D8S45), and L40 (D8S49) - which flank the SRO recognize evolutionarily conserved sequences.
Project description:We report two Japanese patients with Schinzel-Giedion syndrome. When polyhydramnios is observed, additional fetal findings such as overlapping fingers, hydrocephalus, hydronephrosis, and very characteristic facial appearance comprising high, prominent forehead, hypertelorism, and depressed nasal root may suggest Schinzel-Giedion syndrome.
Project description:Schinzel-Giedion syndrome (SGS) is a rare disorder characterized by midface retraction, hypertrichosis, and multiple skeletal anomalies with severe mental retardation. Various skeletal manifestations of the disease have been previously described. We present the first case of SGS developing scoliosis. The patient presented with scoliosis at the age of 8 years which rapidly progressed to severe thoraco-lumbar scoliosis. Survival beyond 2 years is rare in this syndrome. The objective of this report is to describe the possibility of development of scoliosis in SGS due to the neuromuscular nature of the syndrome, especially in long survivors.
Project description:Schinzel-Giedion syndrome (SGS) is a rare developmental disorder characterized by multiple malformations, severe neurological alterations and increased risk of malignancy. SGS is caused by de novo germline mutations clustering to a 12bp hotspot in exon 4 of SETBP1. Mutations in this hotspot disrupt a degron, a signal for the regulation of protein degradation, and lead to the accumulation of SETBP1 protein. Overlapping SETBP1 hotspot mutations have been observed recurrently as somatic events in leukemia. We collected clinical information of 47 SGS patients (including 26 novel cases) with germline SETBP1 mutations and of four individuals with a milder phenotype caused by de novo germline mutations adjacent to the SETBP1 hotspot. Different mutations within and around the SETBP1 hotspot have varying effects on SETBP1 stability and protein levels in vitro and in in silico modeling. Substitutions in SETBP1 residue I871 result in a weak increase in protein levels and mutations affecting this residue are significantly more frequent in SGS than in leukemia. On the other hand, substitutions in residue D868 lead to the largest increase in protein levels. Individuals with germline mutations affecting D868 have enhanced cell proliferation in vitro and higher incidence of cancer compared to patients with other germline SETBP1 mutations. Our findings substantiate that, despite their overlap, somatic SETBP1 mutations driving malignancy are more disruptive to the degron than germline SETBP1 mutations causing SGS. Additionally, this suggests that the functional threshold for the development of cancer driven by the disruption of the SETBP1 degron is higher than for the alteration in prenatal development in SGS. Drawing on previous studies of somatic SETBP1 mutations in leukemia, our results reveal a genotype-phenotype correlation in germline SETBP1 mutations spanning a molecular, cellular and clinical phenotype.
Project description:Schinzel-Giedion syndrome (SGS) is a developmental syndrome, due to the accumulation of SETBP1 protein, which is fatal in early infancy. SGS has a multi-organ involvement with severe and persistent intellectual and physical problems. We produced a human SGS model that outlines disease-relevant phenotypes using patient-derived induced pluripotent stem cells and isogenic controls. Whole transcriptome profiling describes cancer-like alterations in SGS neural progenitors including deregulation of oncogenes and suppressors and enhanced proliferation. These findings demonstrated how SGS post-natal pathological traits mayhave developmental origin in the failure of controlling cell identity and homeostasis due to SETBP1 protein accumulation.
Project description:Schinzel-Giedion syndrome (SGS) is a multiple malformation syndrome characterized by typical facial features, severe neurodevelopmental delay, and multiple congenital abnormalities. SGS is associated with de novo pathogenic variants in the SETBP1 gene. In specific, SETBP1 variants in over 50 patients with classical or non-classical SGS were clustered within exon 4. A male Chinese neonate with dysmorphic facial features, nervous system disorders, and organ malformations at birth was examined in this study and long-term followed-up. Whole-exome sequencing was performed to identify any underlying pathogenic variants in the proband. Additionally, we reviewed the literature that documents the main clinical features and underlying variants of all patients genetically diagnosed with SGS. The neonate had a characteristic midface retraction, abnormal electroencephalogram waveforms, and genital abnormalities. The patient did not initially develop hydronephrosis or undergo a comprehensive skeletal assessment. Six months after birth, the patient had an epileptic seizure and experienced persistent neurodevelopmental delay with auditory and visual abnormalities. Color Doppler ultrasonography at 18 months revealed hydronephrosis and bilateral widening of the lateral ventricles. The patient died suddenly 20.5 months after birth. Whole-exome sequencing revealed a heterozygous de novo variant (c.2605A > G:p.S869G) in exon 4 degradation sequence in SETBP1. The reported de novo heterozygous variant in SETBP1 (c.2605A > G:p.S869G) broadens the knowledge of the scientific community's on the possible SGS genetic alterations. To the best of our knowledge, this is the first report of SETBP1 variant (c.2605A > G:p.S869G) in SGS. The clinical manifestations of neonatal SGS are atypical, and genetic testing is crucial for diagnosis. Long-term follow-up should be conducted after diagnosis to optimize the therapeutic interventions.
Project description:Autosomal recessive diseases are those that require mutations in both alleles to exhibit the disorder. Although most recessive conditions are rare, heterozygous carriers of recessive mutations are quite common. In this study, we show that carriers of Nijmegen Breakage Syndrome (NBS) have a distinct gene expression phenotype that differs from that of noncarriers and also from that of carriers of a similar syndrome, Ataxia Telangiectasia (AT). We found 520 genes whose expression levels differ significantly (P < or = 0.001) between NBS carriers and controls. By linear discriminant analysis, we found a combination of 16 genes that allows 100% correct classification of individuals as either NBS carriers or noncarriers in a training set with 25 individuals, and in a test set with 52 individuals. When applied to AT carriers, the discriminant function misclassified only one out of 18 AT carriers as an NBS carrier. Our result shows that NBS carriers have a specific gene expression phenotype. It suggests that heterozygous mutations can contribute significantly to natural variation in gene expression. This has implications for the role that heterozygosity for recessive diseases plays in the overall genetic architecture of complex human traits and diseases.
Project description:Langer-Giedion's syndrome (LGS) or trichorhinophalangeal syndrome type II (TRPS II; MIM:150230) is a contiguous gene deletion syndrome caused by the haploinsufficiency of the TRPS1 and EXT1 genes. Cornelia de Lange's syndrome (CdLS) is a genetically heterogeneous dysmorphic syndrome where heterozygous mutations of RAD21 gene have been associated with a mild clinical presentation (CDLS type 4; MIM: 614701). We report a female patient with a 2.3-Mb interstitial deletion at 8q23.3-q24.1 encompassing EXT1 and RAD21 genes but not TRPS1 . Clinical findings in this patient are correlated with a mixed phenotype of LGS and CdLS type 4.
Project description:The investigation of genetic forms of juvenile neurodegeneration could shed light on the causative mechanisms of neuronal loss. Schinzel-Giedion syndrome (SGS) is a fatal developmental syndrome caused by mutations in the SETBP1 gene, inducing the accumulation of its protein product. SGS features multi-organ involvement with severe intellectual and physical deficits due, at least in part, to early neurodegeneration. Here we introduce a human SGS model that displays disease-relevant phenotypes. We show that SGS neural progenitors exhibit aberrant proliferation, deregulation of oncogenes and suppressors, unresolved DNA damage, and resistance to apoptosis. Mechanistically, we demonstrate that high SETBP1 levels inhibit P53 function through the stabilization of SET, which in turn hinders P53 acetylation. We find that the inheritance of unresolved DNA damage in SGS neurons triggers the neurodegenerative process that can be alleviated either by PARP-1 inhibition or by NAD + supplementation. These results implicate that neuronal death in SGS originates from developmental alterations mainly in safeguarding cell identity and homeostasis.