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Congenital anomalies of the kidney and urinary tract (CAKUT) constitute one of the most frequent birth defects and represent the most common cause of chronic kidney disease in the first three decades of life. Despite the discovery of dozens of monogenic causes of CAKUT, most pathogenic pathways remain elusive. We performed whole-exome sequencing (WES) in 551 individuals with CAKUT and identified a heterozygous de novo stop-gain variant in ZMYM2 in two different families with CAKUT. Through collaboration, we identified in total 14 different heterozygous loss-of-function mutations in ZMYM2 in 15 unrelated families. Most mutations occurred de novo, indicating possible interference with reproductive function. Human disease features are replicated in X. tropicalis larvae with morpholino knockdowns, in which expression of truncated ZMYM2 proteins, based on individual mutations, failed to rescue renal and craniofacial defects. Moreover, heterozygous Zmym2-deficient mice recapitulated features of CAKUT with high penetrance. The ZMYM2 protein is a component of a transcriptional corepressor complex recently linked to the silencing of developmentally regulated endogenous retrovirus elements. Using protein-protein interaction assays, we show that ZMYM2 interacts with additional epigenetic silencing complexes, as well as confirming that it binds to FOXP1, a transcription factor that has also been linked to CAKUT. In summary, our findings establish that loss-of-function mutations of ZMYM2, and potentially that of other proteins in its interactome, as causes of human CAKUT, offering new routes for studying the pathogenesis of the disorder.
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Proteínas de Ligação a DNA/genética , Epigênese Genética , Fatores de Transcrição Forkhead/genética , Mutação , Proteínas Repressoras/genética , Fatores de Transcrição/genética , Sistema Urinário/metabolismo , Anormalidades Urogenitais/genética , Proteínas de Anfíbios/antagonistas & inibidores , Proteínas de Anfíbios/genética , Proteínas de Anfíbios/metabolismo , Animais , Estudos de Casos e Controles , Criança , Pré-Escolar , Proteínas de Ligação a DNA/metabolismo , Família , Feminino , Fatores de Transcrição Forkhead/metabolismo , Heterozigoto , Humanos , Lactente , Larva/genética , Larva/crescimento & desenvolvimento , Larva/metabolismo , Masculino , Camundongos , Camundongos Knockout , Morfolinos/genética , Morfolinos/metabolismo , Linhagem , Ligação Proteica , Proteínas Repressoras/metabolismo , Fatores de Transcrição/metabolismo , Sistema Urinário/anormalidades , Anormalidades Urogenitais/metabolismo , Anormalidades Urogenitais/patologia , Sequenciamento do Exoma , XenopusRESUMO
Hearing in infants is essential for brain development, acquisition of verbal language skills, and development of social interactions. Therefore, it is important to diagnose hearing loss soon after birth so that interventions can be provided as early as possible. Most newborns in the United States are screened for hearing deficits and commercially available next-generation sequencing hearing loss panels often can identify the causative gene, which may also identify congenital defects in other organs. One of the most prevalent autosomal dominant congenital hearing loss syndromes is branchio-oto-renal syndrome (BOR), which also presents with defects in craniofacial structures and the kidney. Currently, mutations in three genes, SIX1, SIX5, and EYA1, are known to be causative in about half of the BOR patients that have been tested. To uncover new candidate genes that could be added to congenital hearing loss genetic screens, we have combined the power of Drosophila mutants and protein biochemical assays with the embryological advantages of Xenopus, a key aquatic animal model with a high level of genomic similarity to human, to identify potential Six1 transcriptional targets and interacting proteins that play a role during otic development. We review our transcriptomic, yeast 2-hybrid, and proteomic approaches that have revealed a large number of new candidates. We also discuss how we have begun to identify how Six1 and co-factors interact to direct developmental events necessary for normal otic development.
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BACKGROUND/AIMS: We aimed to study the involvement of circZMYM2 (hsa_circ_0099999) in pancreatic cancer (PC) cell proliferation, apoptosis and invasion and to figured out the underlying mechanism of circZMYM2 regulating miR-335-5p and JMJD2C. METHODS: CircRNA differential expressions in twenty PC samples and paired normal tissue samples were analyzed using Arraystar Human CircRNA microarray V1. CircZMYM2 expression level was determined via qRT-PCR. The effects of circZMYM2 inhibition and overexpression on cell proliferation, cell apoptosis and cell invasion were investigated by CCK-8 assays, Flow cytometry assays and Transwell assays. An animal experiment on nude mice was put forward to test the influence of circZMYM2 knockdown on tumor growth. The relationship between circZMYM2, miR-335 and JMJD2C was verified by RNA pull down, dual-luciferase reporter assays and rescue experiment. The effect of circZMYM2 and miR-335-5p on the expression of JMJD2C protein was detected by western blot. RESULTS: CircZMYM2 overexpression was observed in both PC tissues and cells. Knockdown of circZMYM2 inhibited proliferation, induced apoptosis, and weakened invasion ability of cancer cells. Tumor growth was restrained in vivo. CircZMYM2 repressed the expression of its target miR-335-5p. MiR-335-5p attenuated pancreatic cancer development via inhibition of JMJD2C. CONCLUSION: Our study demonstrated that circZMYM2 promoted PC progression. CircZMYM2 had a sponge effect on miR-335-5p and modulated the downstream oncogene JMJD2C.
Assuntos
Regulação Neoplásica da Expressão Gênica , Histona Desmetilases com o Domínio Jumonji/genética , MicroRNAs/genética , Neoplasias Pancreáticas/genética , RNA/genética , Regiões 3' não Traduzidas , Animais , Linhagem Celular , Linhagem Celular Tumoral , Proliferação de Células , Proteínas de Ligação a DNA/genética , Humanos , Camundongos Endogâmicos BALB C , Camundongos Nus , Invasividade Neoplásica/genética , Invasividade Neoplásica/patologia , Neoplasias Pancreáticas/patologia , RNA Circular , Fatores de Transcrição/genéticaRESUMO
Protein SUMOylation has emerged as an important regulatory event, particularly in nuclear processes such as transcriptional control and DNA repair. In this context, small ubiquitin-like modifier (SUMO) often provides a binding platform for the recruitment of proteins via their SUMO-interacting motifs (SIMs). Recent discoveries point to an important role for multivalent SUMO binding through multiple SIMs in the binding partner as exemplified by poly-SUMOylation acting as a binding platform for ubiquitin E3 ligases such as ring finger protein 4. Here, we have investigated whether other types of protein are recruited through multivalent SUMO interactions. We have identified dozens of proteins that bind to multi-SUMO platforms, thereby uncovering a complex potential regulatory network. Multi-SUMO binding is mediated through multi-SIM modules, and the functional importance of these interactions is demonstrated for the transcriptional corepressor ZMYM2/ZNF198 where its multi-SUMO-binding activity is required for its recruitment to chromatin.
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Cromatina/metabolismo , Proteínas de Ligação a DNA/metabolismo , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina/metabolismo , Fatores de Transcrição/metabolismo , Células HEK293 , Humanos , Ligação ProteicaRESUMO
In Potocki-Shaffer syndrome (PSS), the full phenotypic spectrum is manifested when deletions are at least 2.1 Mb in size at 11p11.2. The PSS-associated genes EXT2 and ALX4, together with PHF21A, all map to this region flanked by markers D11S1393 and D11S1319. Being proximal to EXT2 and ALX4, a 1.1 Mb region containing 12 annotated genes had been identified by deletion mapping to explain PSS phenotypes except multiple exostoses and parietal foramina. Here, we report a male patient with partial PSS phenotypes including global developmental delay, craniofacial anomalies, minor limb anomalies, and micropenis. Using microarray, qPCR, RT-qPCR, and Western blot analyses, we refined the candidate gene region, which harbors five genes, by excluding two genes, SLC35C1 and CRY2, which resulted in a corroborating role of PHF21A in developmental delay and craniofacial anomalies. This microdeletion contains the least number of genes at 11p11.2 reported to date. Additionally, we also discuss the phenotypes observed in our patient with respect to those of published cases of microdeletions across the Potocki-Shaffer interval.
Assuntos
Anormalidades Craniofaciais/genética , Deficiências do Desenvolvimento/genética , Deleção de Genes , Histona Desacetilases/genética , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Deleção Cromossômica , Transtornos Cromossômicos/genética , Mapeamento Cromossômico , Cromossomos Humanos Par 11/genética , Anormalidades Craniofaciais/etiologia , Deficiências do Desenvolvimento/etiologia , Exostose Múltipla Hereditária/genética , Face/anormalidades , Feminino , Humanos , Lactente , Masculino , Proteínas de Membrana/genética , Reação em Cadeia da Polimerase em Tempo RealRESUMO
BACKGROUND: Neurodevelopmental-craniofacial syndrome with variable renal and cardiac abnormalities (NECRC) is a rare, autosomal, dominant neurological disorder caused by mutations in the ZMYM2 gene. To date, the clinical and functional characteristics of the novel ZMYM2 mutation c.2090_2091del have not yet been reported. CASE SUMMARY: The patient was an 18.5-mo-old Chinese boy with motor and language delay, microcephaly, facial dysmorphism, moderate malnutrition, single palmar crease on the left hand, synpolydactyly of the right foot, hypotonia and feeding problems. The boy who was diagnosed with NECRC was enrolled in the First Affiliated Hospital, Henan University of Chinese Medicine, and his clinical data were collected. From the whole-exon sequencing (WES) data, the pathogenic SNVs/InDels were identified, and the molecular findings were characterized. WES revealed that the heterozygous variant in the ZMYM2 gene was c.2090_2091del, p.Ser697TrpfsTer3, a frameshift mutation, which is a NECRC-related gene mutation. CONCLUSION: We performed a systematic literature review to identify and characterize NECRC. Substantial evidence from the literature indicated that patients with ZMYM2 gene mutation showed different degrees of intellectual disability, motor and language retardation, facial dysmorphism, and a few had congenital heart defects, kidney and urinary tract abnormalities. Early diagnosis and prompt management with comprehensive rehabilitation training are beneficial, but may not improve long-term outcomes.
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ZMYM2 is a zinc finger transcriptional regulator that plays a key role in promoting and maintaining cell identity. It has been implicated in several diseases such as congenital anomalies of the kidney where its activity is diminished and cancer where it participates in oncogenic fusion protein events. ZMYM2 is thought to function through promoting transcriptional repression and here we provide more evidence to support this designation. Here we studied ZMYM2 function in human cells and demonstrate that ZMYM2 is part of distinct chromatin-bound complexes including the established LSD1-CoREST-HDAC1 corepressor complex. We also identify new functional and physical interactions with ADNP and TRIM28/KAP1. The ZMYM2-TRIM28 complex forms in a SUMO-dependent manner and is associated with repressive chromatin. ZMYM2 and TRIM28 show strong functional similarity and co-regulate a large number of genes. However, there are no strong links between ZMYM2-TRIM28 binding events and nearby individual gene regulation. Instead, ZMYM2-TRIM28 appears to regulate genes in a more regionally defined manner within TADs where it can directly regulate co-associated retrotransposon expression. We find that different types of ZMYM2 binding complex associate with and regulate distinct subclasses of retrotransposons, with ZMYM2-ADNP complexes at SINEs and ZMYM2-TRIM28 complexes at LTR elements. We propose a model whereby ZMYM2 acts directly through retrotransposon regulation, which may then potentially affect the local chromatin environment and associated coding gene expression.
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Elementos de DNA Transponíveis , Retroelementos , Humanos , Dedos de Zinco , Cromatina , Proteínas Correpressoras , Proteínas de Ligação a DNA , Fatores de TranscriçãoRESUMO
We report a case of myeloid/lymphoid neoplasm with ZMYM2::FGFR1 rearrangement (MLNZMYM2::FGFR1) exhibiting a complex disease evolution. This neoplasm initially presented as T-lymphoblastic lymphoma (T-LBL) in lymph node and myeloproliferative neoplasm (MPN) with eosinophilia in bone marrow, then transitioned to systemic mastocytosis (SM) likely accompanied by additional JAK3 and other mutations and finally transformed to acute myeloid leukemia (AML) accompanied by additional/secondary genetic abnormality (gain of chromosome 21, der(13)t(8;13), and RUNX1 mutation). To our knowledge, this is the first case of MLNZMYM2::FGFR1 with a complex trilineage/phenotypic [T-cell (T-LBL), mast cell (SM), and myeloid (MPN and AML)] lineage evolution.
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Ubiquitin-conjugating enzyme E2 B (UBE2B) can form a heterodimer with ubiquitin E3 ligase RAD18. In this study, we aimed to explore new substrates of the UBE2B/RAD18 complex and their regulatory effects in ovarian cancer. Protein physical interactions were predicted using GeneMANIA. Serial sections of commercial ovarian cancer tissue arrays were used to check the protein expression of UBE2B, RAD18, and ZMYM2. Immunofluorescence staining and co-immunoprecipitation assays were performed to check their location and interactions. Cycloheximide chase assay was applied to explore the influence of UBE2B and RAD18 on ZMYM2 degradation. Xenograft tumor models were constructed to assess the influence of the UBE2B-ZMYM2 axis on in vivo tumor growth. A strong positive correlation between UBE2B and ZMYM2 and a moderate positive correlation between RAD18 and ZMYM2 were observed in 23 ovarian cancer cases. In CAOV4 and OVCAR3 cells, myc-ZMYM2 interacted with UBE2B and RAD18. UBE2B and ZMYM2 could be detected in the samples immunoprecipitated by anti-RAD18. UBE2B overexpression or knockdown did not alter ZMYM2 mRNA expression. UBE2B overexpression increased ZMYM2 monoubiquitination but reduced its polyubiquitination. RAD18 knockdown impaired UBE2B-induced ZMYM2 monoubiquitination. UBE2B overexpression significantly enhanced the stability of ZMYM2 protein, the effect of which was weakened by RAD18 knockdown. UBE2B overexpression significantly enhanced the growth of xenograft tumors derived from CAOV4 cells. ZMYM2 knockdown remarkedly suppressed tumor growth and impaired the growth-promoting effect of UBE2B overexpression. In conclusion, this study revealed a novel regulatory effect of the UBE2B/RAD18 complex on ZMYM2 monoubiquitination and stability in ovarian cancer.
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Proteínas de Ligação a DNA , Neoplasias Ovarianas , Fatores de Transcrição , Enzimas de Conjugação de Ubiquitina , Ubiquitina-Proteína Ligases , Animais , Apoptose , Linhagem Celular Tumoral , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Feminino , Humanos , Neoplasias Ovarianas/genética , Antígeno Nuclear de Célula em Proliferação/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Enzimas de Conjugação de Ubiquitina/genética , Enzimas de Conjugação de Ubiquitina/metabolismo , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismoRESUMO
Mouse embryonic stem cells (ESCs) sporadically express preimplantation two-cell-stage (2C) transcripts, including MERVL endogenous retrovirus and Zscan4 cluster genes. Such 2C-like cells (2CLCs) can contribute to both embryonic and extraembryonic tissues when reintroduced into early embryos, although the molecular mechanism underlying such an expanded 2CLC potency remains elusive. We examine global nucleosome occupancy and gene expression in 2CLCs and identified miR-344 as the noncoding molecule that positively controls 2CLC potency. We find that activation of endogenous MERVL or miR-344-2 alone is sufficient to induce 2CLCs with activation of 2C genes and an expanded potency. Mechanistically, miR-344 is activated by DUX and post-transcriptionally represses ZMYM2 and its partner LSD1, and ZMYM2 recruits LSD1/HDAC corepressor complex to MERVL LTR for transcriptional repression. Consistently, zygotic depletion of Zmym2 compromises the totipotency-to-pluripotency transition during early development. Our studies establish the previously unappreciated DUX-miR-344-Zmym2/Lsd1 axis that controls MERVL for expanded stem cell potency.
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Retrovirus Endógenos , MicroRNAs , Animais , Retrovirus Endógenos/genética , Camundongos , MicroRNAs/genética , Células-Tronco Embrionárias Murinas , ZigotoRESUMO
BACKGROUND: The histone methyltransferase SETDB1 (also known as ESET) represses genes and various types of transposable elements, such as endogenous retroviruses (ERVs) and integrated exogenous retroviruses, through a deposition of trimethylation on lysine 9 of histone H3 (H3K9me3) in mouse embryonic stem cells (mESCs). ATF7IP (also known as MCAF1 or AM), a binding partner of SETDB1, regulates the nuclear localization and enzymatic activities of SETDB1 and plays a crucial role in SETDB1-mediated transcriptional silencing. In this study, we further dissected the ATF7IP function with its truncated mutants in Atf7ip knockout (KO) mESCs. RESULTS: We demonstrated that the SETDB1-interaction region within ATF7IP is essential for ATF7IP-dependent SETDB1 nuclear localization and silencing of both ERVs and integrated retroviral transgenes, whereas its C-terminal fibronectin type-III (FNIII) domain is dispensable for both these functions; rather, it has a role in efficient silencing mediated by the SETDB1 complex. Proteomic analysis identified a number of FNIII domain-interacting proteins, some of which have a consensus binding motif. We showed that one of the FNIII domain-binding proteins, ZMYM2, was involved in the efficient silencing of a transgene by ATF7IP. RNA-seq analysis of Atf7ip KO and WT or the FNIII domain mutant of ATF7IP-rescued Atf7ip KO mESCs showed that the FNIII domain mutant re-silenced most de-repressed SETDB1/ATF7IP-targeted ERVs compared to the WT. However, the silencing activity of the FNIII domain mutant was weaker than that of the ATF7IP WT, and some of the de-repressed germ cell-related genes in Atf7ip KO mESCs were not silenced by the FNIII domain mutant. Such germ cell-related genes are targeted and silenced by the MAX/MGA complex, and MGA was also identified as another potential binding molecule of the ATF7IP FNIII domain in the proteomic analysis. This suggests that the FNIII domain of ATF7IP acts as a binding hub of ATF7IP-interacting molecules possessing a specific interacting motif we named FAM and contributes to one layer of the SETDB1/ATF7IP complex-mediated silencing mechanisms. CONCLUSIONS: Our findings contributed to further understanding the function of ATF7IP in the SETDB1 complex, revealed the role of the FNIII domain of ATF7IP in transcriptional silencing, and suggested a potential underlying molecular mechanism for it.
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Domínio de Fibronectina Tipo III , Inativação Gênica , Proteínas Repressoras/metabolismo , Animais , Células Cultivadas , Células HEK293 , Histona-Lisina N-Metiltransferase/metabolismo , Humanos , Camundongos , Células-Tronco Embrionárias Murinas/metabolismo , Ligação Proteica , Proteínas Repressoras/química , Proteínas Repressoras/genéticaRESUMO
FGFR1 translocation may cause myeloid or lymphoid neoplasm but rarely systemic mastocytosis (SM). Conversely, SM is associated with myeloproliferative neoplasm (MPN) but rarely lymphoblastic lymphoma (LBL) or FGFR1 translocation. We report the first case of FGFR1 translocation in a patient with concurrent LBL, MPN, and SM. A 21-year-old male patient presented with diffuse lymphadenopathies and leukocytosis. TdT+/cytoCD3+/CD79aweakly+ LBL was identified in the lymph node. Bone marrow had MPN, SM, and TdT+/CD79a+/cytoCD3weakly+ LBL. The cytogenetic study, reverse-transcription polymerase chain reaction, and sequencing revealed t(8;13)(p11;q12) involving FGFR1 and ZMYM2. Under the hyper-cyclophosphamide, vincristine, doxorubicin, and dexamethasone regimen, complete remission of LBL was achieved despite persistent MPN and SM in the bone marrow. This rare case implies FGFR1 translocation in a precursor cell capable of differentiation into mast cells and lymphoblasts, strengthening the relationship between the 2 tumors in the World Health Organization classification: myeloid and lymphoid neoplasms with FGFR1 abnormalities, and SM with an associated hematologic neoplasm.
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Mastocitose Sistêmica/patologia , Transtornos Mieloproliferativos/patologia , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologia , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/genética , Translocação Genética , Humanos , Masculino , Mastocitose Sistêmica/genética , Transtornos Mieloproliferativos/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Adulto JovemRESUMO
The 8p11 myeloproliferative syndrome (EMS), also known as 8p11 myeloproliferative neoplasm (8p11 MPN), is a collection of rare hematologic malignancies that are associated with fusion genes involving the tyrosine kinase receptor gene FGFR1 in chromosome 8p11. The entity is an aggressive disease with a high rate of transformation to acute myeloid leukemia (AML) and pathologically characterized by its associated eosinophilia. In this study, we reported a distinctive EMS case featuring an in-frame ZMYM2-FGFR1 fusion gene identified by next-generation sequencing technology (NGS). This patient exhibited not only typical EMS signs including elevated white blood cells in peripheral blood and hypercellular bone marrow with marked leukocytosis, but also exceptional characteristics including erythrocytosis in blood and bone marrow basophilia. Moreover, we detected 2 novel genomic mutations in 2 known leukemogenic genes, IKZF1 and ASXL1. Whether these 2 mutations play a part in EMS pathogenesis or contribute to its specific presentations clinically remain to be determined. In summary, we present a unique EMS case involving a ZMYM2-FGFR1 fusion with distinctive hematologic characteristics.
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Proteínas de Ligação a DNA/genética , Transtornos Mieloproliferativos/genética , Proteínas de Fusão Oncogênica/genética , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/genética , Fatores de Transcrição/genética , Sequência de Aminoácidos , Feminino , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Humanos , Pessoa de Meia-Idade , Transtornos Mieloproliferativos/diagnóstico , Transtornos Mieloproliferativos/patologiaRESUMO
OBJECTIVES: Myeloid and lymphoid neoplasms with abnormalities of fibroblast growth factor receptor 1 gene (FGFR1) are a rare and aggressive disease group that harbors translocations of FGFR1 with at least 14 recognized partner genes. We report a case of a patient with a novel t(17;21)(p13;q22) with RUNX1 rearrangement and trilineage blasts. METHODS: A 29-year-old man with relapsed T-lymphoblastic lymphoma in the cervical nodes showed a myeloproliferative neoplasm in his bone marrow with three separate populations of immunophenotypically aberrant myeloid, T-lymphoid, and B-lymphoid blasts by flow cytometry. Cytogenetic and fluorescent in situ hybridization studies showed unique dual translocations of t(8;13)(p11.2;q12) and t(17;21)(p13;q22) with RUNX1 rearrangement. RESULTS: The patient was initiated on a mitoxantrone, etoposide, and cytarabine chemotherapy regimen and died of complications of disease 1 month later. CONCLUSIONS: To our knowledge, this is the first reported case of a myeloid and lymphoid neoplasm with abnormalities of FGFR1 with t(17;21)(p13;q22) and trilineage blasts.
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Subunidade alfa 2 de Fator de Ligação ao Core/genética , Rearranjo Gênico , Transtornos Mieloproliferativos/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/genética , Translocação Genética , Adulto , Medula Óssea/patologia , Cromossomos Humanos Par 13/genética , Cromossomos Humanos Par 17/genética , Cromossomos Humanos Par 21/genética , Cromossomos Humanos Par 8/genética , Evolução Fatal , Humanos , Imunofenotipagem , Hibridização in Situ Fluorescente , Cariotipagem , Masculino , Transtornos Mieloproliferativos/patologia , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologiaRESUMO
Congenital hearing loss is an important clinical problem because, without early intervention, affected children do not properly acquire language and consequently have difficulties developing social skills. Although most newborns in the US are screened for hearing deficits, even earlier diagnosis can be made with prenatal genetic screening. Genetic screening that identifies the relevant mutated gene can also warn about potential congenital defects in organs not related to hearing. We will discuss efforts to identify new candidate genes that underlie the Branchiootorenal spectrum disorders in which affected children have hearing deficits and are also at risk for kidney defects. Mutations in two genes, SIX1 and EYA1, have been identified in about half of the patients tested. To uncover new candidate genes, we have used the aquatic animal model, Xenopus laevis, to identify genes that are part of the developmental genetic pathway of Six1 during otic and kidney development. We have already identified a large number of potential Six1 transcriptional targets and candidate co-factor proteins that are expressed at the right time and in the correct tissues to interact with Six1 during development. We discuss the advantages of using this system for gene discovery in a human congenital hearing loss syndrome.