Sequencing chromosomal abnormalities reveals neurodevelopmental loci that confer risk across diagnostic boundaries.

Balanced chromosomal abnormalities (BCAs) represent a relatively untapped reservoir of single-gene disruptions in neurodevelopmental disorders (NDDs). We sequenced BCAs in patients with autism or related NDDs, revealing disruption of 33 loci in four general categories: (1) genes previously associated with abnormal neurodevelopment (e.g., AUTS2, FOXP1, and CDKL5), (2) single-gene contributors to microdeletion syndromes (MBD5, SATB2, EHMT1, and SNURF-SNRPN), (3) novel risk loci (e.g., CHD8, KIRREL3, and ZNF507), and (4) genes associated with later-onset psychiatric disorders (e.g., TCF4, ZNF804A, PDE10A, GRIN2B, and ANK3). We also discovered among neurodevelopmental cases a profoundly increased burden of copy-number variants from these 33 loci and a significant enrichment of polygenic risk alleles from genome-wide association studies of autism and schizophrenia. Our findings suggest a polygenic risk model of autism and reveal that some neurodevelopmental genes are sensitive to perturbation by multiple mutational mechanisms, leading to variable phenotypic outcomes that manifest at different life stages.

Glycan-Controlled Human PD-1 Variants Displaying Broad-Spectrum High Binding to PD-1 Ligands Potentiate T Cell.

Although therapeutic immunoglobulin G (IgG) antibodies that regulate the activity of immune checkpoints bring innovation to the field of immuno-oncology, they are still limited in their efficiency to infiltrate the tumor microenvironment due to their large molecular size (150 kDa) and the necessity of additional engineering works to ablate effector functions for antibodies targeting immune cells. To address these issues, the human PD-1 (hPD-1) ectodomain, a small protein moiety of 14-17 kDa, has been considered as a therapeutic agent. Here, we used bacterial display-based high-throughput directed evolution to successfully isolate glycan-controlled (aglycosylated or only single-N-linked glycosylated) human PD-1 variants exhibiting over 1000-fold increased hPD-L1 binding affinity compared to that of wild-type hPD-1. The resulting hPD-1 variants, aglycosylated JYQ12 and JYQ12-2 with a single-N-linked glycan chain, showed exceptionally high binding affinity to hPD-L1 and very high affinity to both hPD-L2 and mPD-L1. Moreover, the JYQ12-2 efficiently potentiated the proliferation of human T cells. hPD-1 variants with significantly improved binding affinities for hPD-1 ligands could be used as effective therapeutics or diagnostics that can be differentiated from large-sized IgG antibody-based molecules.

Acetylation of TIP60 at K104 is essential for metabolic stress-induced apoptosis in cells of hepatocellular cancer.

Tumor cells often encounter hypoglycemic microenvironment due to rapid cell expansion. It remains elusive how tumors reprogram the genome to survive the metabolic stress. The tumor suppressor TIP60 functions as the catalytic subunit of the human NuA4 histone acetyltransferase (HAT) multi-subunit complex and is involved in many different cellular processes including DNA damage response, cell growth and apoptosis. Attenuation of TIP60 expression has been detected in various tumor types. The function of TIP60 in tumor development has not been fully understood. Here we found that suppressing TIP60 inhibited p53 K120 acetylation and thus rescued apoptosis induced by glucose deprivation in hepatocellular cancer cells. Excitingly, Lys-104 (K104), a previously identified lysine acetylation site of TIP60 with unknown function, was observed to be indispensable for inducing p53-mediated apoptosis under low glucose condition. Mutation of Lys-104 to Arg (K104R) impeded the binding of TIP60 to human NuA4 complex, suppressed the acetyltransferase activity of TIP60, and inhibited the expression of pro-apoptotic genes including NOXA and PUMA upon glucose starvation. These findings demonstrate the critical regulation of TIP60/p53 pathway in apoptosis upon metabolic stress and provide a novel insight into the down-regulation of TIP60 in tumor cells.

MYBPC1 mutations impair skeletal muscle function in zebrafish models of arthrogryposis.

Myosin-binding protein C1 (MYBPC1) is an abundant skeletal muscle protein that is expressed predominantly in slow-twitch muscle fibers. Human MYBPC1 mutations are associated with distal arthrogryposis type 1 and lethal congenital contracture syndrome type 4. As MYBPC1 function is incompletely understood, the mechanism by which human mutations result in contractures is unknown. Here, we demonstrate using antisense morpholino knockdown, that mybpc1 is required for embryonic motor activity and survival in a zebrafish model of arthrogryposis. Mybpc1 morphant embryos have severe body curvature, cardiac edema, impaired motor excitation and are delayed in hatching. Myofibril organization is selectively impaired in slow skeletal muscle and sarcomere numbers are greatly reduced in mybpc1 knockdown embryos, although electron microscopy reveals normal sarcomere structure. To evaluate the effects of human distal arthrogryposis mutations, mybpc1 mRNAs containing the corresponding human W236R and Y856H MYBPC1 mutations were injected into embryos. Dominant-negative effects of these mutations were suggested by the resultant mild bent body curvature, decreased motor activity, as well as impaired overall survival compared with overexpression of wild-type RNA. These results demonstrate a critical role for mybpc1 in slow skeletal muscle development and establish zebrafish as a tractable model of human distal arthrogryposis.

Translocations disrupting PHF21A in the Potocki-Shaffer-syndrome region are associated with intellectual disability and craniofacial anomalies.

Potocki-Shaffer syndrome (PSS) is a contiguous gene disorder due to the interstitial deletion of band p11.2 of chromosome 11 and is characterized by multiple exostoses, parietal foramina, intellectual disability (ID), and craniofacial anomalies (CFAs). Despite the identification of individual genes responsible for multiple exostoses and parietal foramina in PSS, the identity of the gene(s) associated with the ID and CFA phenotypes has remained elusive. Through characterization of independent subjects with balanced translocations and supportive comparative deletion mapping of PSS subjects, we have uncovered evidence that the ID and CFA phenotypes are both caused by haploinsufficiency of a single gene, PHF21A, at 11p11.2. PHF21A encodes a plant homeodomain finger protein whose murine and zebrafish orthologs are both expressed in a manner consistent with a function in neurofacial and craniofacial development, and suppression of the latter led to both craniofacial abnormalities and neuronal apoptosis. Along with lysine-specific demethylase 1 (LSD1), PHF21A, also known as BHC80, is a component of the BRAF-histone deacetylase complex that represses target-gene transcription. In lymphoblastoid cell lines from two translocation subjects in whom PHF21A was directly disrupted by the respective breakpoints, we observed derepression of the neuronal gene SCN3A and reduced LSD1 occupancy at the SCN3A promoter, supporting a direct functional consequence of PHF21A haploinsufficiency on transcriptional regulation. Our finding that disruption of PHF21A by translocations in the PSS region is associated with ID adds to the growing list of ID-associated genes that emphasize the critical role of transcriptional regulation and chromatin remodeling in normal brain development and cognitive function.

The historical Coffin-Lowry syndrome family revisited: identification of two novel mutations of RPS6KA3 in three male patients.

Coffin-Lowry syndrome (CLS) is a rare X-linked dominant disorder characterized by intellectual disability, craniofacial abnormalities, short stature, tapering fingers, hypotonia, and skeletal malformations. CLS is caused by mutations in the Ribosomal Protein S6 Kinase, 90 kDa, Polypeptide 3 (RPS6KA3) gene located at Xp22.12, which encodes Ribosomal S6 Kinase 2 (RSK2). Here we analyzed RPS6KA3 in three unrelated CLS patients including one from the historical Coffin-Lowry syndrome family and found two novel mutations. To date, over 140 mutations in RPS6KA3 have been reported. However, the etiology of the very first familial case, which was described in 1971 by Lowry with detailed phenotype and coined the term CLS, has remained unknown. More than 40 years after the report, we succeeded in identifying deposited fibroblast cells from one patient of this historic family and found a novel heterozygous 216 bp in-frame deletion, encompassing exons 15 and 16 of RPS6KA3. Drop episodes in CLS patients were reported to be associated with truncating mutations deleting the C-terminal kinase domain (KD), and only one missense mutation and one single basepair duplication involving the C-terminal KD of RSK2 in the patients with drop episode have been reported thus far. Here we report the first in-frame deletion in C-terminal KD of RPS6KA3 in a CLS patient with drop episodes.

Rapid and transient recruitment of DNMT1 to DNA double-strand breaks is mediated by its interaction with multiple components of the DNA damage response machinery.

DNA methylation is an epigenetic mark critical for regulating transcription, chromatin structure and genome stability. Although many studies have shed light on how methylation impacts transcription and interfaces with the histone code, far less is known about how it regulates genome stability. We and others have shown that DNA methyltransferase 1 (DNMT1), the maintenance methyltransferase, contributes to the cellular response to DNA damage, yet DNMT1's exact role in this process remains unclear. DNA damage, particularly in the form of double-strand breaks (DSBs), poses a major threat to genome integrity. Cells therefore possess a potent system to respond to and repair DSBs, or to initiate cell death. In the current study, we used a near-infrared laser microirradiation system to directly study the link between DNMT1 and DSBs. Our results demonstrate that DNMT1 is rapidly but transiently recruited to DSBs. DNMT1 recruitment is dependent on its ability to interact with both PCNA and the ATR effector kinase CHK1, but is independent of its catalytic activity. In addition, we show for the first time that DNMT1 interacts with the 9-1-1 PCNA-like sliding clamp and that this interaction also contributes to DNMT1 localization to DNA DSBs. Finally, we demonstrate that DNMT1 modulates the rate of DSB repair and is essential for suppressing abnormal activation of the DNA damage response in the absence of exogenous damage. Taken together, our studies provide compelling additional evidence for DNMT1 acting as a regulator of genome integrity and as an early responder to DNA DSBs.

WDR11, a WD protein that interacts with transcription factor EMX1, is mutated in idiopathic hypogonadotropic hypogonadism and Kallmann syndrome.

By defining the chromosomal breakpoint of a balanced t(10;12) translocation from a subject with Kallmann syndrome and scanning genes in its vicinity in unrelated hypogonadal subjects, we have identified WDR11 as a gene involved in human puberty. We found six patients with a total of five different heterozygous WDR11 missense mutations, including three alterations (A435T, R448Q, and H690Q) in WD domains important for ß propeller formation and protein-protein interaction. In addition, we discovered that WDR11 interacts with EMX1, a homeodomain transcription factor involved in the development of olfactory neurons, and that missense alterations reduce or abolish this interaction. Our findings suggest that impaired pubertal development in these patients results from a deficiency of productive WDR11 protein interaction.

Targeting levels or oligomerization of nucleophosmin 1 induces differentiation and loss of survival of human AML cells with mutant NPM1.

Nucleophosmin 1 (NPM1) is an oligomeric, nucleolar phosphoprotein that functions as a molecular chaperone for both proteins and nucleic acids. NPM1 is mutated in approximately one-third of patients with AML. The mutant NPM1c+ contains a 4-base insert that results in extra C-terminal residues encoding a nuclear export signal, which causes NPM1c+ to be localized in the cytoplasm. Here, we determined the effects of targeting NPM1 in cultured and primary AML cells. Treatment with siRNA to NPM1 induced p53 and p21, decreased the percentage of cells in S-phase of the cell cycle, as well as induced differentiation of the AML OCI-AML3 cells that express both NPMc+ and unmutated NPM1. Notably, knockdown of NPM1 by shRNA abolished lethal AML phenotype induced by OCI-AML3 cells in NOD/SCID mice. Knockdown of NPM1 also sensitized OCI-AML3 to all-trans retinoic acid (ATRA) and cytarabine. Inhibition of NPM1 oligomerization by NSC348884 induced apoptosis and sensitized OCI-AML3 and primary AML cells expressing NPM1c+ to ATRA. This effect was significantly less in AML cells coexpressing FLT3-ITD, or in AML or normal CD34+ progenitor cells expressing wild-type NPM1. Thus, attenuating levels or oligomerization of NPM1 selectively induces apoptosis and sensitizes NPM1c+ expressing AML cells to treatment with ATRA and cytarabine.

Pan-cancer analysis reveals multifaceted roles of retrotransposon-fusion RNAs.

Transposon-derived transcripts are abundant in RNA sequences, yet their landscape and function, especially for fusion transcripts derived from unannotated or somatically acquired transposons, remains underexplored. Here, we developed a new bioinformatic tool to detect transposon-fusion transcripts in RNA-sequencing data and performed a pan-cancer analysis of 10,257 cancer samples across 34 cancer types as well as 3,088 normal tissue samples. We identified 52,277 cancer-specific fusions with ~30 events per cancer and hotspot loci within transposons vulnerable to fusion formation. Exonization of intronic transposons was the most prevalent genic fusions, while somatic L1 insertions constituted a small fraction of cancer-specific fusions. Source L1s and HERVs, but not Alus showed decreased DNA methylation in cancer upon fusion formation. Overall cancer-specific L1 fusions were enriched in tumor suppressors while Alu fusions were enriched in oncogenes, including recurrent Alu fusions in EZH2 predictive of patient survival. We also demonstrated that transposon-derived peptides triggered CD8+ T-cell activation to the extent comparable to EBV viruses. Our findings reveal distinct epigenetic and tumorigenic mechanisms underlying transposon fusions across different families and highlight transposons as novel therapeutic targets and the source of potent neoantigens.

Therapeutic effects of TM4SF5-targeting chimeric and humanized monoclonal antibodies in hepatocellular and colon cancer models.

The transmembrane 4 L six family member 5 (TM4SF5) is aberrantly expressed in hepatocellular and colorectal cancers, and has been implicated in tumor progression, suggesting that it could serve as a novel therapeutic target. Previously, we screened a murine antibody phage-display library to generate a novel monoclonal antibody, Ab27, that is specific to the extracellular loop 2 of TM4SF5. In this study, we evaluated the effects of chimeric Ab27 using cancer cells expressing endogenous TM4SF5 or stably overexpressing TM4SF5 in vivo and in vitro. Monotherapy with Ab27 significantly decreased tumor growth in liver and colon cancer xenograft models, including a sorafenib-resistant model, and decreased the phosphorylation of focal adhesion kinase (FAK), p27Kip1, and signal transducer and activator of transcription 3 (STAT3). No general Ab27 toxicity was observed in vivo. Combination treatment with Ab27 and sorafenib or doxorubicin exerted higher antitumor activity than monotherapy. In addition, we humanized the Ab27 sequence by the complementarity-determining region (CDR) grafting method. The humanized antibody Ab27-hz9 had reduced immunogenicity but exhibited target recognition and antitumor activity comparable with those of Ab27. Both Ab27 and Ab27-hz9 efficiently targeted tumor cells expressing TM4SF5 in vivo. These observations strongly support the further development of Ab27-hz9 as a novel therapeutic agent against liver and colorectal cancers.

An Fc variant with two mutations confers prolonged serum half-life and enhanced effector functions on IgG antibodies.

The pH-selective interaction between the immunoglobulin G (IgG) fragment crystallizable region (Fc region) and the neonatal Fc receptor (FcRn) is critical for prolonging the circulating half-lives of IgG molecules through intracellular trafficking and recycling. By using directed evolution, we successfully identified Fc mutations that improve the pH-dependent binding of human FcRn and prolong the serum persistence of a model IgG antibody and an Fc-fusion protein. Strikingly, trastuzumab-PFc29 and aflibercept-PFc29, a model therapeutic IgG antibody and an Fc-fusion protein, respectively, when combined with our engineered Fc (Q311R/M428L), both exhibited significantly higher serum half-lives in human FcRn transgenic mice than their counterparts with wild-type Fc. Moreover, in a cynomolgus monkey model, trastuzumab-PFc29 displayed a superior pharmacokinetic profile to that of both trastuzumab-YTE and trastuzumab-LS, which contain the well-validated serum half-life extension Fcs YTE (M252Y/S254T/T256E) and LS (M428L/N434S), respectively. Furthermore, the introduction of two identified mutations of PFc29 (Q311R/M428L) into the model antibodies enhanced both complement-dependent cytotoxicity and antibody-dependent cell-mediated cytotoxicity activity, which are triggered by the association between IgG Fc and Fc binding ligands and are critical for clearing cancer cells. In addition, the effector functions could be turned off by combining the two mutations of PFc29 with effector function-silencing mutations, but the antibodies maintained their excellent pH-dependent human FcRn binding profile. We expect our Fc variants to be an excellent tool for enhancing the pharmacokinetic profiles and potencies of various therapeutic antibodies and Fc-fusion proteins.

Involvement of p54(nrb), a PSF partner protein, in DNA double-strand break repair and radioresistance.

Mammalian cells repair DNA double-strand breaks (DSBs) via efficient pathways of direct, nonhomologous DNA end joining (NHEJ) and homologous recombination (HR). Prior work has identified a complex of two polypeptides, PSF and p54(nrb), as a stimulatory factor in a reconstituted in vitro NHEJ system. PSF also stimulates early steps of HR in vitro. PSF and p54(nrb) are RNA recognition motif-containing proteins with well-established functions in RNA processing and transport, and their apparent involvement in DSB repair was unexpected. Here we investigate the requirement for p54(nrb) in DSB repair in vivo. Cells treated with siRNA to attenuate p54(nrb) expression exhibited a delay in DSB repair in a gamma-H2AX focus assay. Stable knockdown cell lines derived by p54(nrb) miRNA transfection showed a significant increase in ionizing radiation-induced chromosomal aberrations. They also showed increased radiosensitivity in a clonogenic survival assay. Together, results indicate that p54(nrb) contributes to rapid and accurate repair of DSBs in vivo in human cells and that the PSF.p54(nrb) complex may thus be a potential target for radiosensitizer development.

Antimicrobial activities of 1,4-benzoquinones and wheat germ extract.

We evaluated the antibacterial activities of selected edible Korean plant seeds against the food-borne pathogens Staphylococcus aureus KCTC1927, Escherichia coli KCTC2593, Salmonella typhimurium KCTC2054, and Bacillus cereus KCTC1014. While screening for antibacterial agents, we discovered that wheat germ extract contains 2,6-dimethoxy-1,4-benzoquinone (DMBQ) and is highly inhibitory to S. aureus and B. cereus. This is the first report of the antibacterial activity of wheat germ extract. We also investigated the antibacterial activities of the 1,4- benzoquinone standards 1,4-benzoquinone (BQ), hydroquinone (HQ), methoxybenzoquinone (MBQ), and 2,6-dimethoxy- 1,4-benzoquinone (DMBQ). DMBQ and BQ were the most highly inhibitory to S. aureus and S. typhimurium, followed by MBQ and HQ. MICs for DMBQ and BQ ranged between 8 and 64 microgram/ml against the four foodborne pathogens tested. DMBQ and BQ showed significant antibacterial activity; the most sensitive organism was S. aureus with an MIC of 8 microgram/ml. BQ exhibited good activity against S. typhimurium (32 microgram/ml) and B. cereus (32 microgram/ml). The results suggest that wheat germ extract has potential for the development of natural antimicrobials and food preservatives for controlling foodborne pathogens.

Development and characterization of a fully human antibody targeting SCF/c-kit signaling.

CD117/c-kit, a tyrosine kinase receptor, plays a critical role in hematopoiesis, pigmentation, and fertility. The overexpression and activation of c-kit are thought to promote tumor growth and have been reported in various cancers, including leukemia, glioblastoma and mastocytosis. To disrupt the SCF/c-kit signaling axis in cancer, we generated a c-kit antagonist human antibody (NN2101) that binds to domain 2/3 of c-kit. This completely blocked the SCF-mediated phosphorylation of c-kit and inhibited TF-1 cell proliferation, erythroleukemia. In addition, the examination of binding affinity using surface plasmon resonance (SPR) assay showed that NN2101 can bind to c-kit of monkeys (KD = 2.92 × 10-10 M), rats (KD = 1.68 × 10-6 M), mice (KD = 11.5 × 10-9 M), and humans (KD = 2.83 × 10-12 M). We showed that NN2101 does not cause antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity. The immunogenicity of NN2101 was similar to that of bevacizumab. Furthermore, the crystal structure of NN2101 Fab was determined and the structure of NN2101 Fab:c-kit complex was modeled. Structural information, as well as mutagenesis results, revealed that NN2101 can bind to the SCF-binding regions of c-kit. Collectively, we generated a c-kit neutralizing human antibody (NN2101) for the treatment of erythroleukemia and characterized its biophysical properties. NN2101 can potentially be used as a therapeutic antibody to treat different cancers.

Cryopreserved Human Oocytes and Cord Blood Cells Can Produce Somatic Cell Nuclear Transfer-Derived Pluripotent Stem Cells with a Homozygous HLA Type.

Human pluripotent stem cells (PSCs) through somatic cell nuclear transfer (SCNT) may be an important source for regenerative medicine. The low derivation efficiency of stem cells and the accessibility of human oocytes are the main obstacles to their application. We previously reported that the efficiency of SCNT was increased by overexpression of H3K9me3 demethylase. Here, we applied a modified derivation method to the PSC line and first obtained human SCNT-PSC lines derived from both donated cryopreserved oocytes and cord blood cells with a homozygous human leukocyte antigen (HLA) type. The SCNT-PSCs have very similar characteristics with embryonic stem cells (ESCs) and additionally have shown immunocompatibility in an in vitro and in vivo humanized mouse with a matching HLA type. Our study demonstrates that SCNT technology using donated cryopreserved oocytes and cord blood cells with a known HLA type provides a promising method for establishing a human HLA-matched SCNT-PSC bank for regenerative medicine.

The anaphase promoting complex promotes NHEJ repair through stabilizing Ku80 at DNA damage sites.

Double-strand breaks (DSBs) are repaired through two major pathways, homology-directed recombination (HDR) and non-homologous end joining (NHEJ). The choice between these two pathways is largely influenced by cell cycle phases. HDR can occur only in S/G2 when sister chromatid can provide homologous templates, whereas NHEJ can take place in all phases of the cell cycle except mitosis. Central to NHEJ repair is the Ku70/80 heterodimer which forms a ring structure that binds DSB ends and serves as a platform to recruit factors involved in NHEJ. Upon completion of NHEJ repair, DNA double strand-encircling Ku dimers have to be removed. The removal depends on ubiquitylation and proteasomal degradation of Ku80 by the ubiquitin E3 ligases RNF8. Here we report that RNF8 is a substrate of APCCdh1 and the latter keeps RNF8 level in check at DSBs to prevent premature turnover of Ku80.

Erratum: The anaphase promoting complex impacts repair choice by protecting ubiquitin signalling at DNA damage sites.

[This corrects the article DOI: 10.1038/ncomms15751.].

The anaphase promoting complex impacts repair choice by protecting ubiquitin signalling at DNA damage sites.

Double-strand breaks (DSBs) are repaired through two major pathways, homology-directed recombination (HDR) and non-homologous end joining (NHEJ). While HDR can only occur in S/G2, NHEJ can happen in all cell cycle phases (except mitosis). How then is the repair choice made in S/G2 cells? Here we provide evidence demonstrating that APCCdh1 plays a critical role in choosing the repair pathways in S/G2 cells. Our results suggest that the default for all DSBs is to recruit 53BP1 and RIF1. BRCA1 is blocked from being recruited to broken ends because its recruitment signal, K63-linked poly-ubiquitin chains on histones, is actively destroyed by the deubiquitinating enzyme USP1. We show that the removal of USP1 depends on APCCdh1 and requires Chk1 activation known to be catalysed by ssDNA-RPA-ATR signalling at the ends designated for HDR, linking the status of end processing to RIF1 or BRCA1 recruitment.

The presence of two rare genomic syndromes, 1q21 deletion and Xq28 duplication, segregating independently in a family with intellectual disability.

BACKGROUND: 1q21 microdeletion syndrome is a rare contiguous gene deletion disorder with de novo or autosomal dominant inheritance patterns and its phenotypic features include intellectual disability, distinctive facial dysmorphism, microcephaly, cardiac abnormalities, and cataracts. MECP2 duplication syndrome is an X-linked recessive neurodevelopmental disorder characterized by intellectual disability, global developmental delay, and other neurological complications including late-onset seizures. Previously, these two different genetic syndromes have not been reported segregating independently in a same family. CASE PRESENTATION: Here we describe two siblings carrying either a chromosome 1q21 microdeletion or a chromosome Xq28 duplication. Using a comparative genomic hybridization (CGH) array, we identified a 1.24 Mb heterozygous deletion at 1q21 resulting in the loss of 9 genes in a girl with learning disability, hypothyroidism, short stature, sensory integration disorder, and soft dysmorphic features including cupped ears and a unilateral ear pit. We also characterized a 508 kb Xq28 duplication encompassing MECP2 in her younger brother with hypotonia, poor speech, cognitive and motor impairment. The parental CGH and quantitative PCR (qPCR) analyses revealed that the 1q21 deletion in the elder sister is de novo, but the Xq28 duplication in the younger brother was originally inherited from the maternal grandmother through the mother, both of whom are asymptomatic carriers. RT-qPCR assays revealed that the affected brother has almost double the amount of MECP2 mRNA expression compared to other family members of both genders including maternal grandmother and mother who have the same Xq28 duplication with no phenotype. This suggests the X chromosome with an Xq28 duplication in the carrier females is preferentially silenced. CONCLUSION: From our understanding, this would be the first report showing the independent segregation of two genetically unrelated syndromes, 1q21 microdeletion and Xq28 duplication, in a same family, especially in siblings. Although these two chromosomal abnormalities share some similar phenotypes such as intellectual disability, mild dysmorphic features, and cardiac abnormalities, the presence of two unrelated and rare syndromes in siblings is very unusual. Therefore, further comprehensive investigations in similar cases are required for future studies.