Wednesday, November 21, 2018

... and another! Fly study helps point to possible genetic cause of an ARID

Kazeminasab S, Taskiran II, Fattahi Z, Bazazzadegan N, Hosseini M, Rahimi M, Oladnabi M, Haddadi M, Celik A, Ropers HH, Najmabadi H, Kahrizi K. CNKSR1 gene defect can cause syndromic autosomal recessive intellectual disability. Am J Med Genet B Neuropsychiatr Genet. 2018 Nov 18. doi: 10.1002/ajmg.b.32648. PMID: 30450701.

From the abstract: "... A novel frameshift mutation in CNKSR1 gene was detected by Next-Generation Sequencing (NGS) in an Iranian family with syndromic autosomal recessive intellectual disability (ARID). CNKSR1 encodes a connector enhancer of kinase suppressor of Ras 1 ... CNKSR1 interacts with proteins which have already been shown to be associated with intellectual disability (ID) in the MAPK signaling pathway and promotes cell migration through RhoA-mediated c-Jun N-terminal kinase (JNK) activation. Lack of CNKSR1 transcripts and protein was observed in lymphoblastoid cells derived from affected patients using qRT-PCR and western blot analysis ...  RNAi-mediated knockdown of cnk, the CNKSR1 orthologue in Drosophila melanogaster brain, led to defects in eye and mushroom body (MB) structures. In conclusion, our findings support the possible role of CNKSR1 in brain development which can lead to cognitive impairment."

Tuesday, November 20, 2018

Drosophila studies contributed to -- another -- study that identifies a human disease gene

Ansar M, Chung HL, Taylor RL, Nazir A, Imtiaz S, Sarwar MT, Manousopoulou A, Makrythanasis P, Saeed S, Falconnet E, Guipponi M, Pournaras CJ, Ansari MA, Ranza E, Santoni FA, Ahmed J, Shah I, Gul K, Black GC, Bellen HJ, Antonarakis SE. Bi-allelic Loss-of-Function Variants in DNMBP Cause Infantile Cataracts. Am J Hum Genet. 2018 Oct 4;103(4):568-578. PMID: 30290152; PMCID: PMC6174361.

From the abstract: "Infantile and childhood-onset cataracts form a heterogeneous group of disorders; among the many genetic causes, numerous pathogenic variants in additional genes associated with autosomal-recessive infantile cataracts remain to be discovered. We identified three consanguineous families affected by bilateral infantile cataracts. Using exome sequencing, we found homozygous loss-of-function variants in DNMBP ... The phenotypes of all affected individuals include infantile-onset cataracts. RNAi-mediated knockdown of the Drosophila ortholog still life (sif), enriched in lens-secreting cells, affects the development of these cells as well as the localization of E-cadherin, alters the distribution of septate junctions in adjacent cone cells, and leads to a ∼50% reduction in electroretinography amplitudes in young flies. ... We therefore conclude that DNMBP loss-of-function variants cause infantile-onset cataracts in humans."

Big thank you to the US NIH Office of Research Infrastructure Programs (ORIP) for support of projects that generated fly stocks and other resources used in this study.