@article {448, title = {SLC13A5 is the second gene associated with Kohlsch{\"u}tter-T{\"o}nz syndrome.}, journal = {J Med Genet}, volume = {54}, year = {2017}, month = {2017 01}, pages = {54-62}, abstract = {

BACKGROUND: Kohlsch{\"u}tter-T{\"o}nz syndrome (KTZS) is a rare autosomal-recessive disease characterised by epileptic encephalopathy, intellectual disability and amelogenesis imperfecta (AI). It is frequently caused by biallelic mutations in ROGDI. Here, we report on individuals with ROGDI-negative KTZS carrying biallelic SLC13A5 mutations.

METHODS: In the present cohort study, nine individuals from four families with the clinical diagnosis of KTZS and absence of ROGDI mutations as well as one patient with unexplained epileptic encephalopathy were investigated by clinical and dental evaluation, parametric linkage analysis (one family), and exome and/or Sanger sequencing. Dental histological investigations were performed on teeth from individuals with SLC13A5-associated and ROGDI-associated KTZS.

RESULTS: Biallelic mutations in SLC13A5 were identified in 10 affected individuals. Epileptic encephalopathy usually presents in the neonatal and (less frequently) early infantile period. Yellowish to orange discolouration of both deciduous and permanent teeth, as well as wide interdental spaces and abnormal crown forms are major clinical signs of individuals with biallelic SLC13A5 mutations. Histological dental investigations confirmed the clinical diagnosis of hypoplastic AI. In comparison, the histological evaluation of a molar assessed from an individual with ROGDI-associated KTZS revealed hypocalcified AI.

CONCLUSIONS: We conclude that SLC13A5 is the second major gene associated with the clinical diagnosis of KTZS, characterised by neonatal epileptic encephalopathy and hypoplastic AI. Careful clinical and dental delineation provides clues whether ROGDI or SLC13A5 is the causative gene. Hypersensitivity of teeth as well as high caries risk requires individual dental prophylaxis and attentive dental management.

}, keywords = {Alleles, Amelogenesis Imperfecta, Brain Diseases, Cohort Studies, Dementia, Epilepsy, Exome, Female, Genetic Linkage, Genetic Predisposition to Disease, Humans, Male, Membrane Proteins, Mutation, Nuclear Proteins, Pedigree, Symporters, Tooth}, issn = {1468-6244}, doi = {10.1136/jmedgenet-2016-103988}, author = {Schossig, Anna and Bloch-Zupan, Agn{\`e}s and Lussi, Adrian and Wolf, Nicole I and Raskin, Salmo and Cohen, Monika and Giuliano, Fabienne and Jurgens, Julie and Krabichler, Birgit and Koolen, David A and de Macena Sobreira, Nara Lygia and Maurer, Elisabeth and Muller-Bolla, Mich{\`e}le and Penzien, Johann and Zschocke, Johannes and Kapferer-Seebacher, Ines} } @article {199, title = {Assessment of incidental findings in 232 whole-exome sequences from the Baylor-Hopkins Center for Mendelian Genomics.}, journal = {Genet Med}, volume = {17}, year = {2015}, month = {2015 Oct}, pages = {782-8}, abstract = {

PURPOSE: In March 2013 the American College of Medical Genetics and Genomics published a list of 56 genes with the recommendation that pathogenic and likely pathogenic variants detected incidentally by clinical sequencing be reported to patients. As an initial step in determining the practical consequences of this recommendation in the research setting, we searched for variants in these genes in 232 whole-exome sequences from the Baylor-Hopkins Center for Mendelian Genomics.

METHODS: We identified rare, nonsynonymous, and splicing single-nucleotide variants and insertions/deletions and assessed variant classification using the Human Gene Mutation, Emory, and ClinVar databases. We analyzed the burden of mutation in each of the 56 genes and determined which variants should be reported to patients.

RESULTS: Our filtering resulted in 249 distinct variants, with a mean of 1.69 variants per individual. Half of these were novel missense mutations not classified by any of the three reference databases. Of 101 variants listed in the Human Gene Mutation Database, 48 were also in ClinVar and 3 were also in Emory; half of these shared variants were classified discordantly between databases. Some genes consistently had greater variation than others. In total, 0.86\% of individuals had a reportable incidental variant.

CONCLUSION: These observations demonstrate some current challenges of assessing phenotypic consequences of incidental variants for counseling patients.

}, keywords = {Databases, Nucleic Acid, Exome, Female, Genetic Diseases, Inborn, Genomics, High-Throughput Nucleotide Sequencing, Humans, Incidental Findings, Male, Mutation, Polymorphism, Single Nucleotide}, issn = {1530-0366}, doi = {10.1038/gim.2014.196}, author = {Jurgens, Julie and Ling, Hua and Hetrick, Kurt and Pugh, Elizabeth and Schiettecatte, Fran{\c c}ois and Doheny, Kimberly and Hamosh, Ada and Avramopoulos, Dimitri and Valle, David and Sobreira, Nara} } @article {144, title = {Novel COL2A1 variant (c.619G>A, p.Gly207Arg) manifesting as a phenotype similar to progressive pseudorheumatoid dysplasia and spondyloepiphyseal dysplasia, Stanescu type.}, journal = {Hum Mutat}, volume = {36}, year = {2015}, month = {2015 Oct}, pages = {1004-8}, abstract = {

Progressive pseudorheumatoid dysplasia (PPRD) is a rare, autosomal-recessive condition characterized by mild spondyloepiphyseal dysplasia (SED) and severe, progressive, early-onset arthritis due to WISP3 mutations. SED, Stanescu type, is a vaguely delineated autosomal-dominant dysplasia of unknown genetic etiology. Here, we report three individuals from two unrelated families with radiological features similar to PPRD and SED, Stanescu type who share the same novel COL2A1 variant and were matched following discussion at an academic conference. In the first family, we performed whole-exome sequencing on three family members, two of whom have a PPRD-like phenotype, and identified a heterozygous variant (c.619G>A, p.Gly207Arg) in both affected individuals. Independently, targeted sequencing of the COL2A1 gene in an unrelated proband with a similar phenotype identified the same heterozygous variant. We suggest that the p.Gly207Arg variant causes a distinct type II collagenopathy with features of PPRD and SED, Stanescu type.

}, keywords = {Adolescent, Adult, Child, Collagen Type II, Exome, Female, Humans, Joint Diseases, Male, Osteochondrodysplasias, Pedigree, Polymorphism, Single Nucleotide, Radiography, Sequence Analysis, DNA}, issn = {1098-1004}, doi = {10.1002/humu.22839}, author = {Jurgens, Julie and Sobreira, Nara and Modaff, Peggy and Reiser, Catherine A and Seo, Soo Hyun and Seong, Moon-Woo and Park, Sung Sup and Kim, Ok Hwa and Cho, Tae-Joon and Pauli, Richard M} }