Candidate Gene Analysis Identifies Mutations in CYP1B1 and LTBP2 in Indian Families with Primary Congenital Glaucoma.

Genet Test Mol Biomarkers. 2017 Apr;21(4):252-258

Authors: Yang Y, Zhang L, Li S, Zhu X, Sundaresan P

Abstract
BACKGROUND: Primary congenital glaucoma (PCG) is a severe ocular disorder that presents early in life. Cytochrome P4501B1 (CYP1B1) and latent transforming growth factor-beta-binding protein 2 (LTBP2) are the most commonly mutated genes in PCG.
AIM: To investigate the causative genetic mutations in eight Indian families with PCG.
MATERIALS AND METHODS: Whole-exome sequencing was applied to analyze the genomic DNA samples from PCG probands. Sanger sequencing was utilized to confirm the identified mutations.
RESULTS: We identified four homozygous missense mutations (c.1405C>T, p.R469W; c.1397G>T, p.G466V; c.1198C>T, p.P400S; and c.1103G>A, p.R368H) in CYP1B1 and one nonsense mutation (c.2421G>A, p.W807X) in LTBP2 in eight Indian families. Among the five mutations identified, G466V in CYP1B1 and W807X in LTBP2 represent novel mutations.
CONCLUSIONS: Our study expands the mutational spectrum of PCG in the Indian population.

PMID: 28384041 [PubMed - in process]

Autozygosity reveals recessive mutations and novel mechanisms in dominant genes: implications in variant interpretation.

Genet Med. 2017 Apr 06;:

Authors: Monies D, Maddirevula S, Kurdi W, Alanazy MH, Alkhalidi H, Al-Owain M, Sulaiman RA, Faqeih E, Goljan E, Ibrahim N, Abdulwahab F, Hashem M, Abouelhoda M, Shaheen R, Arold ST, Alkuraya FS

Abstract
PURPOSE: The purpose of this study is to describe recessive alleles in strictly dominant genes. Identifying recessive mutations in genes for which only dominant disease or risk alleles have been reported can expand our understanding of the medical relevance of these genes both phenotypically and mechanistically. The Saudi population is enriched for autozygosity, which enhances the homozygous occurrence of alleles, including pathogenic alleles in genes that have been associated only with a dominant inheritance pattern.
METHODS: Exome sequencing of patients from consanguineous families with likely recessive phenotypes was performed. In one family, the genotype of the deceased children was inferred from their parents due to lack of available samples.
RESULTS: We describe the identification of 11 recessive variants (5 of which are reported here for the first time) in 11 genes for which only dominant disease or risk alleles have been reported. The observed phenotypes for these recessive variants were novel (e.g., FBN2-related myopathy and CSF1R-related brain malformation and osteopetrosis), typical (e.g., ACTG2-related visceral myopathy), or an apparently healthy state (e.g., PDE11A), consistent with the corresponding mouse knockout phenotypes.
CONCLUSION: Our results show that, in the era of genomic sequencing and "reverse phenotyping," recessive variants in dominant genes should not be dismissed based on perceived "incompatibility" with the patient's phenotype before careful consideration.Genet Med advance online publication 06 April 2017Genetics in Medicine (2017); doi:10.1038/gim.2017.22.

PMID: 28383543 [PubMed - as supplied by publisher]

A Dominant Mutation in Nuclear Receptor Interacting Protein 1 Causes Urinary Tract Malformations via Dysregulation of Retinoic Acid Signaling.

J Am Soc Nephrol. 2017 Apr 05;:

Authors: Vivante A, Mann N, Yonath H, Weiss AC, Getwan M, Kaminski MM, Bohnenpoll T, Teyssier C, Chen J, Shril S, van der Ven AT, Ityel H, Schmidt JM, Widmeier E, Bauer SB, Sanna-Cherchi S, Gharavi AG, Lu W, Magen D, Shukrun R, Lifton RP, Tasic V, Stanescu HC, Cavaillès V, Kleta R, Anikster Y, Dekel B, Kispert A, Lienkamp SS, Hildebrandt F

Abstract
Congenital anomalies of the kidney and urinary tract (CAKUT) are the most common cause of CKD in the first three decades of life. However, for most patients with CAKUT, the causative mutation remains unknown. We identified a kindred with an autosomal dominant form of CAKUT. By whole-exome sequencing, we identified a heterozygous truncating mutation (c.279delG, p.Trp93fs*) of the nuclear receptor interacting protein 1 gene (NRIP1) in all seven affected members. NRIP1 encodes a nuclear receptor transcriptional cofactor that directly interacts with the retinoic acid receptors (RARs) to modulate retinoic acid transcriptional activity. Unlike wild-type NRIP1, the altered NRIP1 protein did not translocate to the nucleus, did not interact with RARα, and failed to inhibit retinoic acid-dependent transcriptional activity upon expression in HEK293 cells. Notably, we also showed that treatment with retinoic acid enhanced NRIP1 binding to RARα RNA in situ hybridization confirmed Nrip1 expression in the developing urogenital system of the mouse. In explant cultures of embryonic kidney rudiments, retinoic acid stimulated Nrip1 expression, whereas a pan-RAR antagonist strongly reduced it. Furthermore, mice heterozygous for a null allele of Nrip1 showed a CAKUT-spectrum phenotype. Finally, expression and knockdown experiments in Xenopus laevis confirmed an evolutionarily conserved role for NRIP1 in renal development. These data indicate that dominant NRIP1 mutations can cause CAKUT by interference with retinoic acid transcriptional signaling, shedding light on the well documented association between abnormal vitamin A levels and renal malformations in humans, and suggest a possible gene-environment pathomechanism in this disease.

PMID: 28381549 [PubMed - as supplied by publisher]

RGR variants in different forms of retinal diseases: The undetermined role of truncation mutations.

Mol Med Rep. 2016 Nov;14(5):4811-4815

Authors: Li J, Xiao X, Li S, Jia X, Guo X, Zhang Q

Abstract
It has been previously reported that mutations in retinal G protein coupled receptor (RGR) are associated with retinitis pigmentosa. The present study aims to systemically analyze the potential role of variants of RGR in retinal diseases. Variants in coding regions and splice sites of RGR were selected from a whole exome sequencing dataset of 820 probands with various forms of genetic ocular diseases. Potential variants of RGR were further confirmed by Sanger sequencing and analyzed in available family members. Clinical data was reviewed for patients with RGR variants. As a result, a total of five variants in RGR were detected in six probands with different types of ocular diseases. Of the five variants, two were novel heterozygous truncation variations, c.266C>A (p.S89*) and c.722_723delCC (p.S241Yfs*29), identified in two probands with high myopia and confirmed by Sanger sequencing. Segregation analysis on available family members demonstrated p.S89* and p.S241Yfs*29 were also present in unaffected relatives. The other three variants of RGR were heterozygous missense variants randomly occurring in patients with different genetic ocular diseases. No homozygous or compound heterozygous variants were detected. The results of the present study suggested that the heterozygous truncation variants in RGR were less likely to be pathogenic. Further studies are expected to evaluate the pathogenicity of variants in RGR.

PMID: 27748892 [PubMed - indexed for MEDLINE]

The first Japanese case of leukodystrophy with ovarian failure arising from novel compound heterozygous AARS2 mutations.

J Hum Genet. 2016 Oct;61(10):899-902

Authors: Hamatani M, Jingami N, Tsurusaki Y, Shimada S, Shimojima K, Asada-Utsugi M, Yoshinaga K, Uemura N, Yamashita H, Uemura K, Takahashi R, Matsumoto N, Yamamoto T

Abstract
Even now, only a portion of leukodystrophy patients are correctly diagnosed, though various causative genes have been identified. In the present report, we describe a case of adult-onset leukodystrophy in a woman with ovarian failure. By whole-exome sequencing, a compound heterozygous mutation consisting of NM_020745.3 (AARS2_v001):c.1145C>A and NM_020745.3 (AARS2_v001):c.2255+1G>A was identified. Neither of the mutations has been previously reported, and this is the first report of alanyl-transfer RNA synthetase 2 mutation in Asia. We anticipate that further studies of the molecular basis of leukodystrophy will provide insight into its pathogenesis and hopefully lead to sophisticated diagnostic and treatment strategies.

PMID: 27251004 [PubMed - indexed for MEDLINE]

De novo MEIS2 mutation causes syndromic developmental delay with persistent gastro-esophageal reflux.

J Hum Genet. 2016 Sep;61(9):835-8

Authors: Fujita A, Isidor B, Piloquet H, Corre P, Okamoto N, Nakashima M, Tsurusaki Y, Saitsu H, Miyake N, Matsumoto N

Abstract
MEIS2 aberrations are considered to be the cause of intellectual disability, cleft palate and cardiac septal defect, as MEIS2 copy number variation is often observed with these phenotypes. To our knowledge, only one nucleotide-level change-specifically, an in-frame MEIS2 deletion-has so far been reported. Here, we report a female patient with a de novo nonsense mutation (c.611C>G, p.Ser204*) in MEIS2. She showed severe intellectual disability, moderate motor/verbal developmental delay, cleft palate, cardiac septal defect, hypermetropia, severe feeding difficulties with gastro-esophageal reflux and constipation. By reviewing this patient and previous patients with MEIS2 point mutations, we found that feeding difficulty with gastro-esophageal reflux appears to be one of the core clinical features of MEIS2 haploinsufficiency, in addition to intellectual disability, cleft palate and cardiac septal defect.

PMID: 27225850 [PubMed - indexed for MEDLINE]

A PDE3A mutation in familial hypertension and brachydactyly syndrome.

J Hum Genet. 2016 Aug;61(8):701-3

Authors: Boda H, Uchida H, Takaiso N, Ouchi Y, Fujita N, Kuno A, Hata T, Nagatani A, Funamoto Y, Miyata M, Yoshikawa T, Kurahashi H, Inagaki H

Abstract
Hypertension and brachydactyly syndrome (HTNB) with short stature is an autosomal-dominant disorder. Mutations in the PDE3A gene located at 12p12.2-p11.2 were recently identified in HTNB families. We found a novel heterozygous missense mutation c.1336T>C in exon 4 of the PDE3A gene in a Japanese family with multiple HTNB patients. This mutation was found to be completely linked to the family members who inherited this condition. The mutation, resulting in p.Ser446Pro, was located within the cluster region of reported mutations. This mutation may also affect the phosphodiesterase activity of PDE3A to reduce the cyclic AMP level in the cell and thereby influencing the development of limbs and the function of the cardiovascular system.

PMID: 27053290 [PubMed - indexed for MEDLINE]

De novo KCNH1 mutations in four patients with syndromic developmental delay, hypotonia and seizures.

J Hum Genet. 2016 May;61(5):381-7

Authors: Fukai R, Saitsu H, Tsurusaki Y, Sakai Y, Haginoya K, Takahashi K, Hubshman MW, Okamoto N, Nakashima M, Tanaka F, Miyake N, Matsumoto N

Abstract
The voltage-gated Kv10.1 potassium channel, also known as ether-a-go-go-related gene 1, encoded by KCNH1 (potassium voltage-gated channel, subfamily H (eag related), member 1) is predominantly expressed in the central nervous system. Recently, de novo missense KCNH1 mutations have been identified in six patients with Zimmermann-Laband syndrome and in four patients with Temple-Baraitser syndrome. These syndromes were historically considered distinct. Here we report three de novo missense KCNH1 mutations in four patients with syndromic developmental delay and epilepsy. Two novel KCNH1 mutations (p.R357Q and p.R357P), found in three patients, were located at the evolutionally highly conserved arginine in the channel voltage-sensor domain (S4). Another mutation (p.G496E) was found in the channel pore domain (S6) helix, which acts as a hinge in activation gating and mainly conducts non-inactivating outward potassium current. A previously reported p.G496R mutation was shown to produce no voltage-dependent outward current in CHO cells, suggesting that p.G496E may also disrupt the proper function of the Kv channel pore. Our report confirms that KCNH1 mutations are associated with syndromic neurodevelopmental disorder, and also support the functional importance of the S4 domain.

PMID: 26818738 [PubMed - indexed for MEDLINE]

SOFT syndrome caused by compound heterozygous mutations of POC1A and its skeletal manifestation.

J Hum Genet. 2016 Jun;61(6):561-4

Authors: Ko JM, Jung S, Seo J, Shin CH, Cheong HI, Choi M, Kim OH, Cho TJ

Abstract
SOFT syndrome (MIM614813) is an extremely rare primordial dwarfism characterized by short stature, onychodysplasia, facial dysmorphism and hypotrichosis, which is caused by biallelic mutations in the POC1A gene. Only 19 patients with mutation-confirmed SOFT syndrome have been reported to date, all of whom carried homozygous variants that were strongly associated with consanguineous marriages. We report an 8.5-year-old boy with SOFT syndrome showing primordial dwarfism, no effect of growth-hormone therapy and skeletal dysplasia. This is the first report of compound heterozygous variants in POC1A, one previously reported and the other novel. A characteristic skeletal manifestation is reported.

PMID: 26791357 [PubMed - indexed for MEDLINE]

Exome-based genome-wide association study and risk assessment using genetic risk score to prostate cancer in the Korean population.

Oncotarget. 2017 Mar 24;:

Authors: Oh JJ, Lee SJ, Hwang JY, Kim D, Lee SE, Hong SK, Ho JN, Yoon S, Sung J, Kim WJ, Byun SS

Abstract
PURPOSE: To investigate exome-wide genetic variants associated with prostate cancer (PCa) in Koreans and evaluate the discriminative ability by the genetic risk score (GRS).
PATIENTS AND METHODS: We prospectively recruited 1,001 PCa cases from a tertiary hospital and conducted a case-control study including 2,641 healthy men (Stage I). Participants were analyzed using HumanExome BeadChip. For the external validation, additionally enrolled 514 PCa cases and 548 controls (independent cohort) were analyzed for the identified single nucleotide polymorphisms (SNPs) of Stage I (Stage II). The GRS was calculated as a non-weighted sum of the risk allele counts and investigated for accuracy of prediction of PCa.
RESULTS: the mean age was 66.3 years, and the median level of prostate specific antigen (PSA) was 9.19 ng/ml in PCa cases. In Stage I, 4 loci containing 5 variants (rs1512268 on 8p21.2; rs1016343 and rs7837688 on 8q24.21; rs7501939 on 17q12, and rs2735839 on 19q13.33) were confirmed to reach exome-wide significance (p<8.3x10-7). In Stage II, the mean GRS was 4.23 ± 1.44 for the controls and 4.78 ± 1.43 for the cases. As a reference to GRS 4, GRS 6, 7 and 8 showed a statistically significant risk of PCa (OR=1.85, 2.11 and 3.34, respectively).
CONCLUSIONS: The five variants were validated to associate with PCa in firstly performed exome-wide study in Koreans. The addition of individualized calculated GRS effectively enhanced the accuracy of prediction. These results need to be validated in future studies.

PMID: 28380453 [PubMed - as supplied by publisher]

Identification of STXBP2 as a novel susceptibility locus for myocardial infarction in Japanese individuals by an exome-wide association study.

Oncotarget. 2017 Mar 23;:

Authors: Yamada Y, Sakuma J, Takeuchi I, Yasukochi Y, Kato K, Oguri M, Fujimaki T, Horibe H, Muramatsu M, Sawabe M, Fujiwara Y, Taniguchi Y, Obuchi S, Kawai H, Shinkai S, Mori S, Arai T, Tanaka M

Abstract
We performed exome-wide association studies to identify genetic variants-in particular, low-frequency variants with a large effect size-that confer susceptibility to coronary artery disease or myocardial infarction in Japanese. The exome-wide association studies were performed with 12,698 individuals (3488 subjects with coronary artery disease including 2438 with myocardial infarction, 9210 controls) and with the use of the Illumina HumanExome-12 DNA Analysis or Infinium Exome-24 BeadChip. The relation of allele frequencies for 41,339 single nucleotide polymorphisms that passed quality control to coronary artery disease or myocardial infarction was examined with Fisher's exact test. The exome-wide association study for coronary artery disease revealed that 126 single nucleotide polymorphisms were significantly (P <1.21 × 10-6) associated with this condition. Multivariable logistic regression analysis with adjustment for age, sex, and the prevalence of hypertension, diabetes mellitus, and dyslipidemia showed that six of these polymorphisms were related (P < 0.01) to coronary artery disease, but none was significantly (P < 9.92 × 10-5) associated with this condition. The exome-wide association study for myocardial infarction revealed that 114 single nucleotide polymorphisms were significantly (P <1.21 × 10-6) associated with this condition. Multivariable logistic regression analysis with adjustment for covariates revealed that nine of these polymorphisms were related (P < 0.01) to myocardial infarction. Among these nine polymorphisms, rs188212047 [G/T (L212F)] of STXBP2 was significantly (dominant model; P = 4.84 × 10-8; odds ratio, 2.94) associated with myocardial infarction. STXBP2 may thus be a novel susceptibility locus for myocardial infarction in Japanese.

PMID: 28380445 [PubMed - as supplied by publisher]

Severe neurodegeneration, progressive cerebral volume loss and diffuse hypomyelination associated with a homozygous frameshift mutation in CSTB.

Eur J Hum Genet. 2017 Apr 05;:

Authors: Brien A, Marshall CR, Blaser S, Ray PN, Yoon G

Abstract
Mutations of the cystatin B gene (CSTB; OMIM 601145) are known to cause Unverricht-Lundborg disease or progressive myoclonic epilepsy-1A (EPM1A, MIM #254800). Most patients are homozygous for an expanded (>30) dodecamer repeat in the promoter region of CSTB, or are compound heterozygotes for the dodecamer repeat and a point mutation. We report two adolescent sisters born to consanguineous parents of Sri Lankan descent who presented with profound global developmental delay, microcephaly, cortical blindness and axial hypotonia with appendicular hypertonia. Neither sibling ever developed head control, independent sitting or ambulation, and never developed speech. The elder sister had a seizure disorder. Both sisters had profound microcephaly and distinct facial features. On serial brain imaging, they had progressive atrophy of the corpus callosum and supratentorial brain, and diffuse hypomyelination with progressive loss of myelin signal. Exome sequencing revealed both siblings to be homozygous for a c.218dupT (p.His75Serfs*2) mutation in exon 3 of CSTB. The neuroimaging features of our patients are consistent with those observed in Cstb-knockout mice, which supports the hypothesis that disease severity is inversely correlated with the amount of residual functional cystatin B protein.European Journal of Human Genetics advance online publication, 5 April 2017; doi:10.1038/ejhg.2017.39.

PMID: 28378817 [PubMed - as supplied by publisher]

A genome-wide linkage and association analysis of imputed insertions and deletions with cardiometabolic phenotypes in Mexican Americans: The Insulin Resistance Atherosclerosis Family Study.

Genet Epidemiol. 2017 Apr 05;:

Authors: Gao C, Hsu FC, Dimitrov LM, Okut H, Chen YI, Taylor KD, Rotter JI, Langefeld CD, Bowden DW, Palmer ND

Abstract
Insertions and deletions (INDELs) represent a significant fraction of interindividual variation in the human genome yet their contribution to phenotypes is poorly understood. To confirm the quality of imputed INDELs and investigate their roles in mediating cardiometabolic phenotypes, genome-wide association and linkage analyses were performed for 15 phenotypes with 1,273,952 imputed INDELs in 1,024 Mexican-origin Americans. Imputation quality was validated using whole exome sequencing with an average kappa of 0.93 in common INDELs (minor allele frequencies [MAFs] ≥ 5%). Association analysis revealed one genome-wide significant association signal for the cholesterylester transfer protein gene (CETP) with high-density lipoprotein levels (rs36229491, P = 3.06 × 10(-12) ); linkage analysis identified two peaks with logarithm of the odds (LOD) > 5 (rs60560566, LOD = 5.36 with insulin sensitivity (SI ) and rs5825825, LOD = 5.11 with adiponectin levels). Suggestive overlapping signals between linkage and association were observed: rs59849892 in the WSC domain containing 2 gene (WSCD2) was associated and nominally linked with SI (P = 1.17 × 10(-7) , LOD = 1.99). This gene has been implicated in glucose metabolism in human islet cell expression studies. In addition, rs201606363 was linked and nominally associated with low-density lipoprotein (P = 4.73 × 10(-4) , LOD = 3.67), apolipoprotein B (P = 1.39 × 10(-3) , LOD = 4.64), and total cholesterol (P = 1.35 × 10(-2) , LOD = 3.80) levels. rs201606363 is an intronic variant of the UBE2F-SCLY (where UBE2F is ubiquitin-conjugating enzyme E2F and SCLY is selenocysteine lyase) fusion gene that may regulate cholesterol through selenium metabolism. In conclusion, these results confirm the feasibility of imputing INDELs from array-based single nucleotide polymorphism (SNP) genotypes. Analysis of these variants using association and linkage replicated previously identified SNP signals and identified multiple novel INDEL signals. These results support the inclusion of INDELs into genetic studies to more fully interrogate the spectrum of genetic variation.

PMID: 28378447 [PubMed - as supplied by publisher]

Detecting PKD1 variants in polycystic kidney disease patients by single-molecule long-read sequencing.

Hum Mutat. 2017 Apr 04;:

Authors: Borràs DM, Vossen R, Liem M, Buermans HP, Dauwerse H, van Heusden D, Gansevoort RT, den Dunnen JT, Janssen B, Peters DJ, Losekoot M, Anvar SY

Abstract
A genetic diagnosis of autosomal dominant polycystic kidney disease (ADPKD) is challenging due to allelic heterogeneity, high GC-content, and homology of the PKD1 gene with six pseudogenes. Short-read next-generation sequencing (NGS) approaches, such as whole genome (WGS) and whole exome sequencing (WES), often fail at reliably characterizing complex regions such as PKD1. However, long-read single-molecule sequencing has been shown to be an alternative strategy that could overcome PKD1 complexities and discriminate between homologous regions of PKD1 and its pseudogenes. In this study, we present the increased power of resolution for complex regions using long-read sequencing to characterize a cohort of 19 patients with ADPKD. Our approach provided high sensitivity in identifying PKD1 pathogenic variants, diagnosing 94.7% of the patients. We show that reliable screening of ADPKD patients in a single test without interference of PKD1 homologous sequences, commonly introduced by residual amplification of PKD1 pseudogenes, by direct long-read sequencing is now possible. This strategy can be implemented in diagnostics and is highly suitable to sequence and resolve complex genomic regions that are of clinical relevance. This article is protected by copyright. All rights reserved.

PMID: 28378423 [PubMed - as supplied by publisher]

[Genetic methods for analysis of autoinflammatory diseases].

Z Rheumatol. 2017 Apr 04;:

Authors: Bienias M, König N, Wolf C, Kretschmer S, Rösen-Wolff A, Berner R, Tüngler V, Lee-Kirsch MA

Abstract
Over the past years the phenotypic and genetic spectrum of autoinflammatory diseases has continuously increased. Moreover, several monogenic autoinflammatory disorders have now been identified where febrile episodes are not among the leading symptoms and which can be accompanied by autoimmune phenomena and susceptibility to infections. Autoinflammatory conditions that are characterized by uncontrolled activity of cytokines, such as interleukin-1 beta (IL1β), tumor necrosis factor alpha (TNF-α) and type 1 interferons (1-IFN), are amenable to specific therapeutic interventions. Thus, identification of the underlying genetic cause is important. During diagnostic work-up, genetic testing of a patient with autoinflammation should be carried out depending on the clinical presentation. If a distinct disorder is suspected, sequencing of the causative gene should be performed. Genetic tests using next generation sequencing (NGS), such as panel sequencing, exome sequencing and array comparative genomic hybridization (CGH) can be carried out if symptoms cannot be assigned to a specific disease entity.

PMID: 28378116 [PubMed - as supplied by publisher]

A novel WDR62 mutation causes primary microcephaly in a large consanguineous Saudi family.

Ann Saudi Med. 2017 Mar-Apr;37(2):148-153

Authors: Naseer MI, Rasool M, Sogaty S, Chaudhary RA, Mansour HM, Chaudhary AG, Abuzenadah AM, Al-Qahtani MH

Abstract
BACKGROUND: Primary microcephaly (MCPH) is a rare developmental defect characterized by impaired cognitive functions, retarded neurodevelopment and reduced brain size. It is genetically heterogeneous and more than 17 genes so far have been identified that are associated with this disease.
OBJECTIVE: To study the genetic defect in a consanguineous Saudi family with primary microcephaly.
DESIGN: Cross-sectional clinical genetics study of a Saudi family.
SETTING: Medical genomics research center.
PATIENTS AND METHODS: Blood samples collected from six members of a family of healthy consanguineous parents were analyzed by whole exome sequencing to identify the underlying pathogenic mutations in two members of the family (23-year-old female and 7-year-old male) who presented with primary microcephaly, intellectual disability, delayed psychomotor development and walking difficulty, speech impedi-ments and seizures.
MAIN OUTCOME MEASURE(S): Detection of mutation in the WD repeat domain 62 (WDR62) gene in a family segregating autosomal recessive primary microcephaly.
RESULTS: The exome variant analysis identified a novel missense mutation (c.3878C > A) in WDR62 gene in exon 30 resulting in amino acid change from alanine to aspartate (p.Ala1293Asp). Further validation in the affected patients and healthy members of family and 100 unrelated healthy persons as controls confirmed it to be pathogenic.
CONCLUSIONS: Functional impairment of the WDR62 gene can lead to severe neurodevelopmental de-fects, brain malformations and reduced head size. A missense mutation of exon 30 changed alanine to aspartate in the WDR62 protein leading to the typical MCPH phenotype.
LIMITATIONS: Mutation was identified in a single family.

PMID: 28377545 [PubMed - in process]

Caution in interpretation of disease causality for heterozygous loss-of-function variants in the MYH8 gene associated with autosomal dominant disorder.

Eur J Med Genet. 2017 Apr 01;:

Authors: Dai Z, Whitt Z, Mighion LC, Pontoglio A, Bean LJ, Colombo R, Hegde M

Abstract
To date, the NM_002472.2(MYH8):c.2021G>A (p.Arg674Gln) missense variant in the MYH8 gene is the only known genetic change in individuals with autosomal dominant trismus-pseudocamptodactyly syndrome with unknown molecular mechanism. Next-generation sequencing (NGS), including targeted gene panels and whole-exome sequencing, is routinely performed in many clinical diagnostic laboratories as standard-of-care testing aimed at identifying disease-causing genomic variants. Whole-exome sequencing has revealed loss-of-function variants in the MYH8 gene. To properly classify the MYH8 loss-of-function variants, we either retrieved them from public databases or retrospectively collected them from individuals genetically tested by custom NGS panels or by whole-exome sequencing and confirmed using Sanger sequencing. We further evaluated the respective clinical presentations of these individuals with the MYH8 loss-of-function variants. Heterozygous loss-of-function variants in the MYH8 gene were detected in 16 individuals without trismus-pseudocamptodactyly syndrome. Four of these 16 individuals had a pathogenic or likely pathogenic variant detected in another gene that could explain their clinical presentation. Moreover, there are ∼100 MYH8 heterozygous protein-truncating and splice site variants in the ExAC database in different populations. Our results, combined with the population data, indicate that loss-of-function variants in the MYH8 gene do not cause autosomal dominant trismus-pseudocamptodactyly syndrome, and the clinical significance of these variants remains unknown at present. This result highlights the importance of considering the molecular mechanism of disease, variants published in the medical literature, and population genomic data for the correct interpretation of loss-of-function variants in genes associated with autosomal dominant diseases.

PMID: 28377322 [PubMed - as supplied by publisher]

Novel Presentation of Rosai-Dorfman Histiocytosis With a Prolonged Course of Cranial and Peripheral Neuropathies.

Pediatr Neurol. 2017 Mar 08;:

Authors: Tripathi R, Serajee F, Jiang H, Huq AH

Abstract
BACKGROUND: Rosai-Dorfman disease is a form of histiocytosis affecting the systemic lymph nodes. Intracranial Rosai-Dorfman disease is rare and presents with extra-parenchymal or intraparenchymal proliferative mass lesions. Cranial neuropathy has not been reported in Rosai-Dorfman disease except when caused by mass effect by an adjacent lesion.
PATIENT DESCRIPTION: We describe a girl with Rosai-Dorfman disease who presented with peripheral and multiple cranial neuropathies. Detailed clinical, immunologic, neurophysiology, imaging, and genetic studies were performed. She had a prolonged course but recovered fully after immune therapies. She had increased titers of striated muscle and smooth muscle antibodies. Imaging studies revealed contrast enhancement of cranial nerves and striated muscles. Demyelination was evident in the nerve twigs from muscle biopsy. Exome sequencing did not reveal a genetic mutation.
CONCLUSIONS: Most patients with Rosai-Dorfman disease have a benign course, but severe neurological dysfunction due to bulbar involvement and cranial and peripheral neuropathies may occur. Treatment with immunoglobulin and steroids may be of benefit.

PMID: 28377039 [PubMed - as supplied by publisher]

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Cousins not twins: intra and inter-tumoral heterogeneity in syndromic neuroendocrine tumours.

J Pathol. 2017 Mar 31;:

Authors: Flynn A, Dwight T, Benn D, Deb S, Colebatch AJ, Fox S, Harris J, Duncan EL, Robinson B, Hogg A, Ellul J, To H, Duong C, Miller JA, Yates C, James P, Trainer A, Gill AJ, Clifton-Bligh R, Hicks RJ, Tothill RW

Abstract
Hereditary endocrine neoplasias, including phaeochromocytoma/paraganglioma and medullary thyroid cancer, are caused by autosomal dominant mutations in several familial cancer genes. A common feature of these diseases is the presentation of multiple primary tumours, or multifocal disease representing independent tumour clones that have arisen from the same initiating genetic lesion, but have undergone independent clonal evolution. Such tumours provide an opportunity to discover common co-operative changes required for tumorigenesis, while controlling for the genetic background of the individual. We performed genomic analysis of synchronous and metachronous tumours from five patients bearing germline mutations in the genes SDHB, RET and MAX. Using whole exome sequencing and high-density SNP arrays, we analyzed two to four primary tumours from each patient. We also applied multi-regional sampling, to assess intra-tumoral heterogeneity and clonal evolution, in two cases involving phaeochromocytoma/paraganglioma and medullary thyroid cancer, respectively. Heterogeneous patterns of genomic change existed between synchronous or metachronous tumours, with evidence of branching evolution. We observed striking examples of evolutionary convergence involving the same rare somatic copy-number events in synchronous primary phaeochromocytoma/paraganglioma. Convergent events also occurred during clonal evolution of metastatic medullary thyroid cancer. These observations suggest that genetic or epigenetic changes acquired early within precursor cells, or pre-existing within the genetic background of the individual, create contingencies that determine the evolutionary trajectory of the tumour.

PMID: 28369925 [PubMed - as supplied by publisher]