Rothmund-Thomson Syndrome Type 2 in an African American/Puerto Rican Child Demonstrates Diagnostic Challenges in Diverse Population.

Rothumnd-Thomson syndrome (RTS) is a rare genetic condition characterized by poikiloderma, sparse hair, short stature, skeletal abnormalities, cataracts, and increased risk for malignancies. The presenting symptom is often a classic rash with erythema on the cheeks and face with spread to extensor surfaces of extremities. Gradually over months to years, this rash develops into poikiloderma (reticulated hyper- and hypopigmentation, telangiectasias, and areas of punctate atrophy). Identification of this characteristic rash may facilitate early diagnosis and management in patients with RTS; however, this may be more challenging in patients from diverse populations, especially with darker skin. Herein, we report an African-American/Puerto Rican 4-year, 11-month-old male who presented with feeding difficulties, scaly patches of skin, sparse hair, short stature, hypertelorism, and developmental delay. Initially, poikiloderma on his extremities was considered to be psoriasiform dermatitis. Exome sequencing revealed compound heterozygous pathogenic variants in the RECQL4 gene, c.1568_1573delGCCCCTinsCCCCC (p.Ser523fs) and c.2412_2420delGGCCGGGCG (p.Ala805_Arg807del) confirming a diagnosis of RTS type 2. This report underscores the risk of misdiagnosis or delayed diagnoses of RTS in diverse populations and highlights the importance of comprehensive molecular evaluation in diagnosing and managing rare conditions.