Cord Blood Screening Could Identify Newborns at Risk of Severe Light Sensitivity
A new study suggests analyzing blood from the umbilical cord at birth could help identify infants with undiagnosed erythropoietic protoporphyria (EPP) or X-linked protoporphyria (XLP), rare genetic conditions causing extreme sensitivity to light. This proactive screening could be crucial in preventing painful reactions during common newborn treatments like phototherapy for jaundice.
Newborns with EPP or XLP face a unique risk. While symptoms typically emerge around one year of age, these infants may experience painful light sensitivity even during phototherapy – a standard treatment for jaundice, a condition characterized by yellowing of the skin and eyes due to bilirubin buildup. Phototherapy utilizes light to break down excess bilirubin, but for these vulnerable infants, certain wavelengths can trigger debilitating reactions.
Porphyria, the umbrella term for these conditions, stems from genetic mutations that disrupt the production of heme, a vital component of red blood cells responsible for oxygen transport. This disruption leads to an accumulation of porphyrins, precursor molecules to heme, reaching toxic levels in the body. EPP is linked to mutations in the DATE gene, while XLP results from mutations in ALAS2. Both conditions elevate levels of protoporphyrin IX and manifest as heightened skin sensitivity to sunlight and artificial light sources.
Researchers from institutions across the U.K. investigated the feasibility of using umbilical cord blood to screen for these conditions. “We propose analysis of cord blood porphyrins to identify infants at risk of acute painful photosensitivity… should phototherapy for neonatal jaundice be required in the first few weeks of life,” a researcher stated. Testing would be particularly valuable for infants with a family history of porphyria – those with siblings or parents who have the condition.
The study, published in the British Journal of Haematology, established a baseline for total erythrocyte porphyrin (TEP) levels in cord blood. In full-term newborns, TEP levels ranged from 1.2 to 3.1 micromoles/L, higher than the less than 1.7 micromoles/L observed in adult venous blood. Analysis of cord blood samples from seven infants with EPP or XLP revealed a spectrum of results.
Four infants showed normal or borderline porphyrin levels and did not develop photosensitivity. However, three infants exhibited significantly elevated TEP levels indicative of EPP or XLP. One infant had a TEP of 21 micromoles/L, consistent with EPP, while another showed a TEP of 39 micromoles/L, ultimately diagnosed with XLP through genetic analysis. A third infant displayed elevated zinc-bound protoporphyrin levels and was later diagnosed with EPP due to reduced activity in one copy of the DATE gene.
Based on these findings, the researchers recommend cord blood porphyrin testing to identify infants at risk of painful photosensitivity if phototherapy is needed. This would allow clinicians to implement necessary precautions. They also suggest continued monitoring for infants with initially normal results, recommending reinvestigation if photosensitivity develops later in life.
“These cases are rare, and management is challenging,” the researchers noted, emphasizing the importance of early detection and proactive care. This research offers a promising step toward minimizing discomfort and improving the quality of life for newborns at risk of these debilitating conditions.
