Further evidence of dominant inheritance of Kabuki syndrome

Department of Cheshire and Merseyside Regional Clinical Genetics Service, Alder Hey Hospital, Liverpool, UK.
Clinical dysmorphology (Impact Factor: 0.61). 08/2009; 18(4):215-7. DOI: 10.1097/MCD.0b013e32832c012e
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    ABSTRACT: MLL2 mutations are detected in 55 to 80% of patients with Kabuki syndrome (KS). In 20 to 45% patients with KS, the genetic basis remains unknown, suggesting possible genetic heterogeneity. Here, we present the largest yet reported cohort of 116 patients with KS. We identified MLL2 variants in 74 patients, of which 47 are novel and a majority are truncating. We show that pathogenic missense mutations were commonly located in exon 48. We undertook a systematic facial KS morphology study of patients with KS at our regional dysmorphology meeting. Our data suggest that nearly all patients with typical KS facial features have pathogenic MLL2 mutations, although KS can be phenotypically variable. Furthermore, we show that MLL2 mutation-positive KS patients are more likely to have feeding problems, kidney anomalies, early breast bud development, joint dislocations and palatal malformations in comparison with MLL2 mutation-negative patients. Our work expands the mutation spectrum of MLL2 that may help in better understanding of this molecule, which is important in gene expression, epigenetic control of active chromatin states, embryonic development and cancer. Our analyses of the phenotype indicates that MLL2 mutation-positive and -negative patients differ systematically, and genetic heterogeneity of KS is not as extensive as previously suggested. Moreover, phenotypic variability of KS suggests that MLL2 testing should be considered even in atypical patients.
    Full-text · Article · Nov 2011 · European journal of human genetics: EJHG
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    ABSTRACT: Kabuki syndrome (KS) is a congenital syndrome with an estimated prevalence of 1 in 32 000. Individuals with the syndrome have multiple malformations, but remain identifiable by the presence of the distinctive craniofacial anomalies associated with the condition. Discovered in 1981 by two independent groups of Japanese scientists, spearheaded by Yoshikazu Kuroki and Norio Niikawa, much ambiguity relating to the syndrome persisted for over 30 years after it was initially discovered, with no definitive conclusions about its etiology having ever been established. Recently, mutations within the MLL2 gene have been identified as potentially implicative. Mutations within the MLL2 gene in KS patients have been promising not only because of their relatively high presence in affected individuals, but also because of pre-existing information in the literature having validated mutant MLL2 genes in KS as a highly significant finding. Although found to be present in the majority of cases, the absence of MLL2 mutations in all patients with the syndrome is suggestive that the condition may still display a degree of genetic heterogeneity, and further still, present with more complex inter genomic interactions than initially proposed.
    No preview · Article · Mar 2012 · Journal of Human Genetics
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    ABSTRACT: Most patients with Kabuki syndrome (KS) are the only person in their family with the condition. However, familial cases of KS have been described showing evidence that this syndrome can be inherited as a dominant trait with variable expressivity. We report on two related individuals with facial findings characteristic of KS. The proposita had arched eyebrows, long and upward slanting palpebral fissures, cleft lip and palate, retromicrognathia, brachydactyly of hands and feet, stubby fingers, nail hypoplasia, and prominent finger pads. Her mother had eyebrows with dispersed lateral half, long and upward slanting palpebral fissures, retrognathia, abnormal and posteriorly rotated ears, prominent finger pads, brachydactyly of feet, learning difficulties, and psychomotor development delay. DNA sequencing revealed a novel missense mutation in the MLL2 gene in both the proposita and her mother. The mutation (p.R5432Q) was found in the exon 51, within the SET domain of the gene, which confers methyltransferase activity on the protein. Therefore, the epigenetic and transcriptional regulatory properties of this protein may be altered and this suggests that the mutation is the cause of phenotype observed in both the patient and her mother. The clinical signs and the molecular evidence in this family further support the notion that KS is an autosomal dominant condition with variable expressivity. To our knowledge this is the first report of a Brazilian family with recurrence of this syndrome.
    No preview · Article · Aug 2012 · American Journal of Medical Genetics Part A