Sirenomelia with an angiomatous lumbosacral myelocystocele in a full-term infant.

Sirenomelia, also known as the mermaid syndrome, is a rare congenital malformation of uncertain etiology. It is characterized by fusion of the lower limbs and commonly associated with severe urogenital and gastrointestinal malformations. In this report, we describe the first case of an infant with sirenomelia and a massive angiomatous lumbosacral myelocystocele

Loss of the Cytoskeletal Protein Pdlim7 Predisposes Mice to Heart Defects and Hemostatic Dysfunction

<div><p>The actin-associated protein Pdlim7 is essential for heart and fin development in zebrafish; however, the expression and function of this PDZ-LIM family member in the mammal has remained unclear. Here, we show that Pdlim7 predominantly localizes to actin-rich structures in mice including the heart, vascular smooth muscle, and platelets. To test the requirement for Pdlim7 in mammalian development and function, we analyzed a mouse strain with global genetic inactivation of Pdlim7. We demonstrate that Pdlim7 loss-of-function leads to significant postnatal mortality. Inactivation of Pdlim7 does not disrupt cardiac development, but causes mild cardiac dysfunction in adult mice. Adult <i>Pdlim7</i>^<i>-/-</i> mice displayed increased mitral and tricuspid valve annulus to body weight ratios. These structural aberrations in <i>Pdlim7</i>^<i>-/-</i> mice were supported by three-dimensional reconstructions of adult cardiac valves, which revealed increased surface area to volume ratios for the mitral and tricuspid valve leaflets. Unexpectedly, we found that loss of Pdlim7 triggers systemic venous and arterial thrombosis, leading to significant mortality shortly after birth in <i>Pdlim7</i>^<i>+/-</i> (11/60) and <i>Pdlim7</i>^<i>-/-</i> (19/35) mice. In line with a prothrombotic phenotype, adult <i>Pdlim7</i>^<i>-/-</i> mice exhibit dramatically decreased tail bleed times compared to controls. These findings reveal a novel and unexpected function for Pdlim7 in maintaining proper hemostasis in neonatal and adult mice. </p> </div

Atrioventricular valves of adult Pdlim7^-/- mice display abnormal morphology.

<p>Histological sections from 3-month old WT and Pdlim7^-/- hearts stained with Masson’s Trichrome (A-D) and Alcian blue (E-F) exhibit normal distribution of collagens (blue, A-D) and glycosaminoglycans (blue, E-F), but elongated mitral valves in Pdlim7^-/- mice (arrows, B, F; n=5) compared to WT controls (A, E; n=3). Scale bar = 100 μm. Representative 3D reconstructions of serial sections of mitral (pink) and tricuspid (turquoise) valves from a WT (G) and Pdlim7^-/- (H) mouse in the same anterodorsolateral perspective. Table providing quantification of increased surface area to volume ratios of atrioventricular valves in Pdlim7^-/- (mitral, n=5; tricuspid, n=4) compared to WT (mitral, n=6; tricuspid, n=5) controls (I). *p<0.04. LV = left ventricle; MV = mitral valve; SA = surface area; TV = tricuspid valve; Vol = volume.</p

Adult Pdlim7^-/- mice exhibit mild cardiac dysfunction with increased valve annulus dimensions.

<p>Representative Doppler profile in the apical-4 chamber view of mitral valve inflow velocities (A-B) and mitral valve annulus measurement (E-F) from WT (n=8) and Pdlim7^-/- (n=9) mice. Box-and-whisker plots reveal normal fractional shortening (FS) and ejection fraction (EF) in Pdlim7^-/- mice (C), but an increased Tei index (D) and increased mitral and tricuspid annulus dimensions to body weight ratios (G) as compared to controls, *p<0.01. A = late filling; AV = atrioventricular; E = early filling; ET = ejection time; IVCT = isovolumetric contraction time; IVRT = isovolumetric relaxation time; LV = left ventricle; MV = mitral valve; RV = right ventricle.</p

Generation of <i>Pdlim7</i> mutant mice.

<p>Schematic representation of the retroviral integration site within intron two of the <i>Pdlim7</i> gene (A). Exons are depicted by yellow boxes with WT and viral-specific genotyping primers represented by arrows and an arrowhead, respectively. Genotyping reveals a 230bp PCR fragment representing the WT allele and a 190bp product for the viral integration (B). Semi-quantitative RT-PCR demonstrates absence of <i>Pdlim7</i> gene transcripts in adult uteri of Pdlim7^-/- mice using GAPDH as control (C). Western blot shows that Pdlim7^-/- and Pdlim7^+/- mice express only -1.18 ± 2.64% and 29.36 ± 14.92% Pdlim7 protein compared to WT controls, respectively (D). Sagittal section through the aorta demonstrates Pdlim7 antibodies (green) localize to filamentous actin (red) of smooth muscle in WT, but not Pdlim7^-/- embryos (E), further verifying loss of Pdlim7 protein in null mice (control DAPI nuclei, blue). LTR = long terminal repeat; SA and SD = splice acceptor and donor sites, respectively; IRES = internal ribosomal entry site; BGEO = lacZ gene; pA = polyadenylation signal; PGK = phosphoglycerate kinase gene; BTK = Bruton’s tyrosine kinase gene. </p

Pathological analysis of non-surviving <i>Pdlim7</i> mutant pups reveals pre-mortem thrombi.

<p><i>Pdlim7</i>^+/- (n=3) and <i>Pdlim7</i>^-/- (n=11) perinatal lethal pups exhibit extensive blood clots in the heart, arteries (arrowhead), and veins (arrows, B-C’) associated with atrial dilation and lung congestion compared to WT (n=7) controls (A-A’). Example of pre-mortem blood clots in the right ventricle (E-E’), umbilical vessel (G-G’), and lung alveoli (I-I’) of a Pdlim7^-/- perinatal lethal pup compared to WT control (D, F, H). Boxes depict location of high magnification image in E’, G’, and I’. Arrows point to attachment of the thrombus to the vessel wall (E’, I’) and arrowhead points to recanalization of the clot (G’). Scale bar = 1mm (A-C’), 50 µm (D-I), 20 µm (G’, I’), and 10µm (E’). </p