Mutations in Either TUBB or MAPRE2 Cause Circumferential Skin Creases Kunze Type

Abstract

Circumferential skin creases Kunze type (CSC-KT) is a specific congenital entity with an unknown genetic cause. The disease phenotype comprises characteristic circumferential skin creases accompanied by intellectual disability, a cleft palate, short stature, and dysmorphic features. Here, we report that mutations in either MAPRE2 or TUBB underlie the genetic origin of this syndrome. MAPRE2 encodes a member of the microtubule end-binding family of proteins that bind to the guanosine triphosphate cap at growing microtubule plus ends, and TUBB encodes a β-tubulin isotype that is expressed abundantly in the developing brain. Functional analyses of the TUBB mutants show multiple defects in the chaperone-dependent tubulin heterodimer folding and assembly pathway that leads to a compromised yield of native heterodimers. The TUBB mutations also have an impact on microtubule dynamics. For MAPRE2, we show that the mutations result in enhanced MAPRE2 binding to microtubules, implying an increased dwell time at microtubule plus ends. Further, in vivo analysis of MAPRE2 mutations in a zebrafish model of craniofacial development shows that the variants most likely perturb the patterning of branchial arches, either through excessive activity (under a recessive paradigm) or through haploinsufficiency (dominant de novo paradigm). Taken together, our data add CSC-KT to the growing list of tubulinopathies and highlight how multiple inheritance paradigms can affect dosage-sensitive biological systems so as to result in the same clinical defect.

SMCHD1 mutations associated with a rare muscular dystrophy can also cause isolated arhinia and Bosma arhinia microphthalmia syndrome

“…Fluorescence imaging of GFP-positive cells on ventrally positioned larvae was conducted as described 82 . In parallel, we obtained lateral brightfield images of whole larvae using the VAST onboard camera.…”

De Novo Disruption of the Proteasome Regulatory Subunit PSMD12 Causes a Syndromic Neurodevelopmental Disorder

“…[51][52][53] Finally, to assess the role of psmd12 in craniofacial development, we therefore injected CRISPR sgRNA into the -1.4col1a1:egfp transgenic line embryos at the 1-cell stage. -1.4col1a1:egfp demonstrates GFP signal in cartilages.…”

“…54 For imaging, 3 dpf larvae were positioned and imaged live with the Vertebrate Automated Screening Technology platform (version 1.2.2.8, Union Biometrica) in a manner similar to previously described methods. 53,55 We assessed craniofacial patterning by either measuring the angle of the ceratohyal cartilage at 3 dpf or by counting the number of ceratobranchial arch pairs at 3 dpf. We were then able to quantify two types of craniofacial abnormalities from GFP-positive cells in -1.4col1a1:egfp CRISPR F0 mutants.…”

Mutations in TMEM260 Cause a Pediatric Neurodevelopmental, Cardiac, and Renal Syndrome

“…We and others have demonstrated previously the utility of zebrafish models in testing the candidacy of rare mutations in syndromic disorders; [14][15][16][17][18][19][20][21] this approach includes an experimental paradigm in which expression of mutations in the context of spliced isoforms can be used for testing the specific effect of such alleles. 14,22-24 For TMEM260, we utilized this approach to ask (1) whether the transient suppression or introduction of deletions at the locus can reproduce key aspects of the human pathology, (2) whether the two known isoforms of the human locus might have different abilities to rescue relevant phenotypes, and (3) whether the long TMEM260 isoform harboring individual 2-II-4's mutation (c.1698_1701del) has the ability to rescue relevant phenotypes.…”