A two-month-old infant is brought to emergency depament with marked respiratory distress. On examination, the infant has cyanosis and bilateral crepitations. Hea rate is 180/min, respiratory rate 56/min and the liver span 7.5 cm. The child had repeated episodes of fever, cough and respiratory distress since the time of bih. Cardiovascular examination reveals a grade III ejection systolic murmur in left para-sternal area and the chest X-ray reveals cardiomegaly with a narrow base and plethoric lung fields. What is the most likely diagnosis?

- In the given case scenario, infant has features of hea failure, cyanosis with repeated episodes of pneumonia suggesting increased pulmonary blood flow. - These clinical features along with the chest X ray findings are suggestive of Transposition of great aeries. - ON X-RAY : 'Egg on side' or 'Egg on string' appearance is characteristic of transposition of great aeries Other options: Congenital methemoglobinemia: Inherited in autosomal recessive pattern Diagnosed by genetic testing/ blood tests CYSTIC FIBROSIS: Mutation in gene encoding for CFTR - Located on long arm of chromosome 7 Presents with recurrent bronchiolitis in infancy, recurrent lower resp tract infections, bronchiectasis, steatorrhea, pancreatitis & azoospermia Diagnosed by presence of typical phenotype/ family history & confirmed by high sweat chloride on atleast 2 occasions/ by identifying mutation in both copies of CFTR TOF: Doesn't present with cyanosis at bih. X-ray shows Boot shaped hea.