Alagille syndrome (ALGS; MIM: 118450) is caused by monoallelic pathogenic variants in JAG1 or NOTCH2. ALGS is characterized by paucity of interlobular bile ducts, congenital heart defects (commonly pulmonary artery stenosis), butterfly-shaped vertebrae, posterior embryotoxon, and characteristic facies1. Mild intellectual disability, renal structural abnormalities, and vascular anomalies may also occur1.

We present an infant with mild pulmonary artery stenosis (PAS) and a rare lymphatic anomaly, with evidence supporting a heterozygous likely pathogenic variant in JAG1 as the cause. The pregnancy was complicated by moderate fetal abdominal ascites. Fetal echocardiogram was normal. The infant was delivered by Cesarean section at 34 weeks 1 day due to maternal preeclampsia, polyhydramnios, and non-immune fetal hydrops. Shortly after birth, the ascites was drained and the infant was placed on high flow oscillatory ventilation for respiratory failure. A peritoneal drain was placed for recurring ascites. Octreotide was ineffective. Lymphatic evaluation demonstrated a tortuous thoracic duct and large volume ascites (Figure 1A, E). Intramesenteric, intrahepatic and intranodal magnetic resonance lymphangiography (MRL) demonstrated a peritoneal leak and backflow into the mesentery (Figure 1B–D), consistent with a diagnosis of central conducting lymphatic anomaly (CCLA). No embolization was performed. An initial physical examination demonstrated flat forehead; low posterior hairline; maxillary hypoplasia with prominent eyes bilaterally; hypertelorism; depressed nasal bridge; bulbous nasal tip; and widelyspaced nipples. There was no evidence of renal tubular acidosis on laboratory studies. Immunological studies showed low T cells and hypogammaglobulinema. Echocardiogram showed small atrial septal defect not requiring intervention. Cardiac catheterization demonstrated mild PAS. Gamma glutamyl transferase was elevated (193-462 Units/Liter). There was no biliary ductal dilatation on MRL. Review of chest, abdomen and pelvic computed tomography showed no vertebral or renal anomalies. Ophthalmology evaluation revealed nystagmus with good fixation and age-appropriate hyperopic astigmatism without evidence of posterior embryotoxon. An eye ultrasound was not performed. At 14 months, the chylous ascites is improved. The patient is tolerating a regular pediatric diet and is growing well.