Atrial septal defect in cyanotic CL/Fr mice

Area of Science:

• Developmental Biology
• Craniofacial Anomalies
• Cardiology

Background:

• Newborn mice with cleft lip and palate (CLP) sometimes exhibit cyanosis, previously attributed to atrial septal defects (ASD).
• Previous research indicated a correlation between cyanotic symptoms and more severe CLP types.
• A hypothesis suggested mechanical airway obstruction due to palatal shelf and tongue development issues in CLP mice might cause cyanosis.

Purpose of the Study:

• To investigate the relationship between atrial septal defects (ASD) and cyanosis in newborn CLP mice.
• To determine if ASD or palatal shelf development is the primary cause of cyanosis in CL/Fr mice.

Main Methods:

• Histological examination of newborn hearts from CLP(-), noncyanotic CLP(+), cyanotic CLP(+), CL/Fr, and ICR mice.
• Determination of ASD incidence and size on neonatal day 0 and days 1-4 for CLP(-) newborns.
• Assessment of palatal shelf development in CLP(+) newborns.

Main Results:

• CL/Fr mice showed a high incidence of ASD (approx. 80%), unlike ICR mice (0%).
• Septum primum was shorter in cyanotic CLP(+) mice on neonatal day 0, but ASD incidence and septal development rates did not differ significantly between cyanotic and noncyanotic CLP(+) mice.
• Cyanotic newborns exhibited significantly less developed palatal shelves compared to noncyanotic newborns.

Conclusions:

• Cyanosis in CL/Fr mice appears unrelated to ASD or septal development rates.
• Cyanosis is likely associated with the occurrence of CLP itself in this mouse strain.
• A relationship between palatal shelf development and cyanosis in CLP mice was confirmed, supporting the airway obstruction hypothesis.