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99mTechnetium pyridoxylidene glutamate imaging in visceral heterotaxy (Ivemark's syndrome).

A two and one-half year old boy with complex congenital heart disease had Howell-Jolly bodies in his blood raising the possibility of the asplenia syndrome. A 99mTc-sulfur colloid liver-spleen scan was reported normal, but the right lobe of the abnormally reversed liver was mistaken for the spleen. The diagnosis of visceral heterotaxy (Ivemark's syndrome) was established after scanning the patient with a new radiopharmaceutical, 99mTechnetium pyridoxylidene glutamate. The agent clearly demonstrated a left-sided gall bladder, and on comparison with the sulfur colloid scan it was established that asplenia was present. Radionuclide imaging with the new generation of hepatobiliary agents is a reliable method to document asplenia and is useful in studying patients with visceral heterotaxy.

Child, Preschool

Further Support for Association of DAND5 with Autosomal Recessive Laterality Disorders.

BACKGROUND: Laterality defects are rare congenital malformations that encompass congenital heart defects (CHDs) together with abnormalities of visceral organ arrangement (situs inversus or situs ambiguous). These defects may be isolated or part of a syndromic presentation with multisystem involvement. While over 50 genes have been implicated in laterality disorders, across multiple modes of inheritance, many cases remain molecularly undiagnosed. We sought to elucidate the molecular basis of dextrocardia, CHDs and visceral heterotaxy in two unrelated individuals of Arab-Muslim descent. METHODS: Detailed clinical phenotyping and exome sequencing (ES) were performed for each of the probands, followed by familial segregation analysis. RESULTS: ES revealed a shared homozygous variant in the Dan Domain Family Member 5 (DAND5) gene (NM_152654.3): c.396_397dup, p.(Tyr133SerfsTer11). DAND5 encodes a member of the Cerberus-related DAN protein family, which is involved in the establishment of left body asymmetry. This frameshift variant introduces a premature stop codon within the final exon, which is predicted to escape nonsense-mediated decay (NMD), resulting in a truncated protein lacking the functional DAN domain. CONCLUSIONS: DAND5 has recently been suggested as a candidate gene in heterotaxy and CHDs. Our findings further support biallelic loss of function variants in DAND5 autosomal recessive laterality defects.

Female

Mapping Shroom3 expression across the adult mouse.

Shroom3 is an actin binding protein integral to apical constriction and apical-basal elongation during mammalian morphogenesis. Shroom3 function has been demonstrated in the development of the heart, neural tube, gut tube, eye, thyroid bud, and kidneys, with mutations linked to human congenital defects including anencephaly, spina bifida, cleft lip and palate, and ventricular septal defects. Genome-wide association studies implicate Shroom3 in human conditions such as chronic kidney disease and heterotaxy. While this suggests that Shroom3 expression continues postnatally, the extent of adult expression patterns remain unexplored. To address this, we first harvested organs from adult mice heterozygous for a LacZ reporter inserted into the Shroom3 allele (Shroom3+/Gt). Organs were stained in wholemount with X-gal and cleared in glycerol to identify which tissues expressed Shroom3 and to localize the expression within the tissue. Wildtype organs were then harvested and fluorescently stained to localize Shroom3 protein in tissue sub-structures. From this, we have characterized previously unknown Shroom3 expression in many adult organs including the bladder and reproductive systems, as well as established postnatal Shroom3 expression in organs thought to only have developmental expression including the eye and whisker pad. Our results also demonstrate organs which did not show Shroom3 expression, including the liver and pancreas. This data suggests that Shroom3 has roles in a wider number of tissues than previously thought and provides a foundation for future hypotheses regarding the biological and pathological significance of Shroom3.

Animals

Atypical Prenatal Phenotypic Spectrum: A Case Series of Four Unique Presentations With Genetic and Diagnostic Insights.

Prenatal diagnosis of genetic syndromes often relies on structural anomalies; however, many monogenic disorders show atypical or evolving prenatal phenotypes, limiting imaging-based diagnosis. We report four fetuses with atypical presentations diagnosed by exome/genome sequencing. Pathogenic variants were identified in BBS1, SLC26A2, POMT2, and COL25A1. Prenatal findings included heterotaxy with complex heart disease, isolated long bone shortening, subtle CNS anomalies, and recurrent contractures. These cases highlight the variability in the prenatal phenotypic spectrum of genetic disorders and the value of genomic sequencing for accurate genetic counseling and reproductive decision-making.

Humans

[Right aortic arch associated with congenital heart defects].

The author's experience in the association of right aortic arch and congenital cardiac malformations is reported. We found 56 cases out of 1200 congenital cardiac malformations which constitutes 4.6%. In the classification of Knight and Edwards, type I right aortic arch was the most frequent (96%) and it was associated principally with Tetralogy of Fallot (46%), transposition of the great vessels (14.3%), truncus arteriosus (12%), tricuspid atresia (10.7%) and complex cardiac malformations associated with the syndrome of visceral heterotaxy (10.7%). In type II and type III we found only one case of each and these were associated with pulmonary valvular stenosis, atrial septal defect and ventricular septal defect. It is noted that the right aortic arch has never been associated with total anomalous pulmonary venous return nor with mitral or aortic valvular malformations.

Aorta, Thoracic