TITLE:
Partial Trisomy 12p in a Preterm Infant with Dysmorphic Features, Recurrent Apnea, Feeding Dysfunction, Neuroimaging Abnormalities, and a Large Left Diaphragmatic Hernia: A Case Report
AUTHORS:
Yasser Mohamed El Gohary, Nuha Al Zaabi, Ahmed Adnan, Luay Abdalwahab, Olfat Al Zaabi, Reem Mahmoud, Ashraf Abboud Elabatal, Mohamed Ali Kasem, Aly Rashwan, Anshad Ummerkhan, Nawal Nawabjan, Wasimah Amanullah, Mays Alrim, Somar Alhourany
KEYWORDS:
Partial Trisomy 12p, Chromosome 12 Duplication, Prematurity, Neonatal Dysmorphism, Apnea, Feeding Dysfunction, Hypotonia, Diaphragmatic Hernia, Chromosomal Microarray
JOURNAL NAME:
Open Access Library Journal,
Vol.13 No.9,
September
30,
2026
ABSTRACT: Partial trisomy 12p is a rare chromosomal disorder caused by duplication of the short arm of chromosome 12. Its clinical manifestations are variable and may include craniofacial dysmorphism, developmental delay, hypotonia, feeding difficulties, and congenital anomalies. Neonatal presentations, particularly in preterm infants, remain infrequently reported. We report a preterm female infant born at 31 weeks and 5 days of gestation, with a birth weight of 1.6 kg, to a mother with diabetes mellitus. The infant required positive-pressure ventilation at birth, continuous positive airway pressure, subsequent intubation, and one dose of surfactant for respiratory distress syndrome. During a prolonged neonatal intensive care unit stay, she developed hypotonia, recurrent apnea with oxygen desaturation and bradycardia, excessive airway secretions, impaired sucking and swallowing, and prolonged dependence on respiratory support. Chromosomal microarray analysis demonstrated a pathogenic copy-number gain involving 12p13.33-p11.1, consistent with partial trisomy 12p. Neuroimaging revealed mild ventriculomegaly, germinal matrix cystic changes interpreted as sequelae of prior intraventricular hemorrhage, and later CT abnormalities concerning for hypoxic-ischemic injury. At 4 months of age, persistent respiratory and feeding difficulties prompted further diagnostic evaluation, which identified a large left diaphragmatic hernia containing the stomach and spleen within the left hemithorax, associated with compressive atelectatic changes in the left lower lobe and adjacent consolidation. Following multidisciplinary assessment and family counseling, pediatric surgical repair was recommended. This case expands the documented neonatal phenotype of partial trisomy 12p and highlights the importance of continued diagnostic reassessment when respiratory and feeding abnormalities persist despite an established genetic diagnosis. The diaphragmatic hernia may have contributed substantially to respiratory morbidity; however, the recurrent apnea was likely multifactorial, and a causal relationship between the 12p duplication and the diaphragmatic hernia cannot be established from a single case.