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Trisomy 16 in the mouse fetus associated with generalized edema and cardiovascular and urinary tract anomalies
Abstract:
Murine trisomy (Ts) 16 occurs in the fetal and neonatal progeny of males doubly heterozygous for the Robertsonian metacentric chromosomes Rb(16.17)7Bnr/Rb(9.16)9Rma and "all acrocentric" females. The developmental aspects of this trisomy were studied between day 12 of gestation and birth. So far, postnatal survival longer than a few hours after birth has not been observed. The frequency of Ts 16 among all implants decreased from more than 20% on day 14 to values between 4% and 7% shortly before term. Main features of Ts 16 are moderate general hypoplasia, slight developmental retardation, and cardiovascular anomalies. These latter were found in 96% of the trisomies, the great majority belonging to the transposition type, i.e., riding aorta, double outlet right ventricle (DORV) and transposition of the great arteries (TGA). Association with common atrio ventricular (AV)-canal was frequent. Other anomalies as "open eyelid", hydronephrosis, and hydroureter seem to be attributable to the effects of retardation. Generalized transient edema was frequent in the later gestational stages of Ts 16. Severe cardiovascular malformation is possible one of the factors responsible for late fetal or neonatal death in some cases. Another factor probably contributing to Ts 16 fetal mortality is insufficiency of placental function due to hypoplasia of the fetal vasculature of this organ. The teratological study of Ts 16 demands interest since evidence has been forwarded to consider this trisomy as an animal model of human trisomy 21.
Insights
Murine trisomy 16 (Ts 16) in mice causes developmental issues, including severe cardiovascular anomalies and hypoplasia. This trisomy is a potential animal model for human Down syndrome (trisomy 21).
Area of Science:
- Developmental Biology
- Genetics
- Teratology
Background:
- Murine trisomy 16 (Ts 16) arises from specific Robertsonian translocations.
- Ts 16 is associated with significant developmental abnormalities and high prenatal mortality.
Purpose of the Study:
- To investigate the developmental aspects of Ts 16 from mid-gestation to birth.
- To characterize the phenotypic features and mortality factors of Ts 16.
- To evaluate Ts 16 as a potential model for human trisomy 21.
Main Methods:
- Analysis of Ts 16 development in mouse embryos and fetuses.
- Detailed examination of morphological anomalies, including cardiovascular defects.
- Assessment of placental function and fetal survival rates.
Main Results:
- Ts 16 fetuses exhibit moderate hypoplasia, developmental retardation, and frequent cardiovascular anomalies (96%), predominantly transpositions like DORV and TGA.
- Common atrioventricular canal, open eyelid, hydronephrosis, and edema were observed.
- Placental hypoplasia and cardiovascular malformations contribute to high fetal and neonatal mortality.
Conclusions:
- Ts 16 is characterized by severe cardiovascular malformations and developmental deficits.
- The murine Ts 16 model offers insights into the developmental consequences of trisomy.
- Ts 16 serves as a valuable animal model for studying human trisomy 21 and its associated pathologies.