A human laterality disorder caused by a homozygous deleterious mutation inMMP21

Abstract

Background Laterality in the vertebrate embryo is determined by left–right asymmetric gene expression driven by the flow of extraembryonic fluid across the embryonic node. Defects in these processes cause heterotaxy, the abnormal formation and arrangement of visceral organs that can range from complete inversion of symmetry to the selective misarrangement of organs. However, our understanding of the genetic causality for laterality defects in human beings remains relatively limited. Methods We performed whole exome sequencing in a consanguineous family with heterotaxia. To interrogate the pathogenic potential of the discovered variant, we used an in vivo system in which the potential of the candidate gene to induce L-R asymmetry was tested by transient suppression and CRISPR/Cas9-induced deletions. We also used in vitro assays to test a possible link between our exome-derived candidate and Notch signaling. Results We identified a homozygous 2 bp deletion in MMP21, encoding matrix metalloproteinase-21, as the sole coding mutation that segregated with the phenotype. Transient suppression or CRISPR/Cas9-mediated deletion of mmp21 in zebrafish embryos induced cardiac looping defects, with concomitant disruption of laterality markers in the lateral plate mesoderm and disrupted notch signalling in vitro and in vivo. Conclusions Our data implicate loss of MMP21 as a cause of heterotaxy in humans with concomitant defects in Notch signaling. In support of this finding, a homozygous missense mutation in MMP21 was identified previously in mice with N-Ethyl-N-Nitrosourea (ENU)-induced heterotaxy. Taken together, these observations suggest a role of matrix metalloproteinases in the establishment of asymmetric organ development, likely through the regulation of morphogenetic signals.

RAC1 Missense Mutations in Developmental Disorders with Diverse Phenotypes

“…Guide RNAs targeting the Danio rerio coding region of rac1 were generated as previously described. 34,35 We observed sequence aberrations in 30% of the evaluated rac1 clones ( Figure S2A). Assessment of mosaic F0 embryos injected with a guide against exon 2 did not result in statistically different head size counts between F0 CRISPR and control embryos ( Figure S2B).…”

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

“…We generated capture libraries by using the SureSelect Human All Exon 50 Mb Kit (V4, Agilent Technologies) and obtained 100 bp paired-end reads on a HiSeq 2000 instrument (Illumina) with a mean of 573 coverage across the two samples (Table S1) as previously described. 5 We (Table S4). We confirmed that both parents were heterozygous, the affected siblings were each homozygous at this site, and five unaffected siblings were either wild-type (WT) or heterozygous carriers ( Figure 1A).…”

Un gène codant une métalloprotéase impliqué dans l’hétérotaxie

“…ne souffraient d'autres signes que ceux liés à l'hétérotaxie, suggérant que les mutations du gène MMP21 n'altéraient pas d'autres mécanismes cellulaires que celui lié à la latéralisation. En plus de ces huit familles, un cas familial supplémentaire hispano-américain est rapporté dans l'article de Guimier et al [5], ainsi que trois autres cas, dont deux familiaux, dans d'autres études indépendantes [6,7]. MMP21 code une protéine probablement sécrétée car elle présente une région amino-terminale contenant un peptide signal 1 .…”

“…L'expression de cette métalloprotéase est observée dans de multiples tissus embryonnaires et adultes, ainsi que dans des tumeurs cancéreuses [8]. Les mutations rapportées ont été trouvées dans tous les domaines de la protéine (Figure 2) [5][6][7], démontrant que celleci doit être intègre pour fonctionner normalement.…”

“…Pour ces huit familles identifiées, aucun des malades . L'emplacement des mutations est symbolisé en-dessous de la protéine, avec en noir les mutations de l'article de Guimier et al [5], et en bleu les mutations rapportées dans deux autres articles [6,7]. nécessaires à l'arrimage et à la fusion des granules à la membrane plasmique [3,4] (➜).…”