Fig. 2

Zebrafish modelling of the chromosome 4 CNV showing disruption in eye and midbrain development.

A Comparative images of the eye in wild-type (mab21l2^wt/wt), lrba homozygous knockout fish (lrba^mw716/mw716), fish with a homozygous deletion of the CNV identified in Individual III.5 (Family 2) (mab21l2^mw715/mw715) and fish compound heterozygous for the deletion and a p.Gln48Serfs*5 frameshift allele in mab21l2 (mab21l2^mw715/mw702). Red arrows: misshapen eyecups with a visible gap between the neuroectodermal layers of the optic vesicle (ventral coloboma); white arrows: optic tectum; blue arrows: gap resulting from the reduced size of optic tectum; asterisks: small lens; R: retina; L: lens; OT: optic tectum. B, C Histogram of the lens diameter (B) and eye width (proximal to distal) (C) of wild-type and homozygous mab21l2^mw715 fish at 24hpf (n = 17 and 18, correspondingly), 48hpf (n = 22 and 30) and 72hpf (n = 29 and 30). Lens diameter was significantly reduced in mutant fish at 24hpf (p < 0.000001) and 48hpf (p = 0.001282), but not at 72hpf (p = 0.121573). Eye width was subtly decreased in mutant fish at 72hpf (p = 0.028665), but not at 24hpf (p = 0.520299) or 48hpf (p = 0.300519). Statistical analyses: two-tailed t test for two independent samples with Welch correction for unequal variances. Dmab21l2 (yellow) and foxe3 (green) mRNA expression in whole mount wild-type and homozygous mab21l2^mw715 fish. White arrows indicate the position of the midbrain (M), eye (E), and lens (L): the mutants exhibited a visibly reduced mab21l2 expression in the midbrain region, and a slightly reduced mab21l2 staining in the eyes at 20- and 24hpf; foxe3 expression (green) in the developing lens was detected at all stages, showing a smaller lens in 20- and 24hpf mutant embryos. Panels (B and C): Black bars: wild-type; greyscale bars: homozygous mab21l2^mw715 embryos (24hpf: medium grey; 48hpf: grey; 72hpf: dark grey); * p ≤ 0.05, ** p ≤ 0.01, ***p ≤ 0.001, ****p ≤ 0.0001. Source data is provided in the Source Data file.