A comprehensive genotype-phenotype evaluation of eight Chinese probands with Waardenburg syndrome

Concurrent Cardiac and Renal Anomalies in Waardenburg Syndrome Type 1: A Report of a Rare Case

Waardenburg syndrome (WS) is an autosomal dominant genetic disorder characterized by the absence of melanocytes, leading to distinctive pigmentary abnormalities and sensorineural hearing loss. This case report describes extremely rare concurrent anomalies in a preterm male infant diagnosed with WS type 1. The newborn, delivered prematurely at 35 weeks due to maternal complications, presented with multiple congenital anomalies and required immediate resuscitation. He exhibited hallmark features of WS, including a white forelock, dystopia canthorum, and bilateral sensorineural hearing loss. Genetic testing confirmed a PAX3 gene mutation. The infant experienced significant respiratory and feeding challenges, necessitating intensive care. Management included mechanical ventilation, surfactant therapy, phototherapy for hyperbilirubinemia, and broad-spectrum antibiotics for suspected sepsis. The cardiac assessment revealed multiple anomalies, such as a patent foramen ovale and left ventricular hypertrophy, while renal ultrasound identified multicystic dysplastic kidney and bilateral hydronephrosis. Multidisciplinary care facilitated the infant's stabilization, transition to oral feeding, and ongoing specialized care. WS type 1 is associated with mutations in the PAX3 gene and presents with diverse clinical manifestations. Although renal and cardiac anomalies are uncommon in WS, their presence in this case underscores the complexity of the syndrome. Early intervention for hearing impairment and genetic counseling are critical for optimal outcomes. This report highlights the importance of a comprehensive and interdisciplinary approach to managing infants with WS, addressing both typical and atypical manifestations. It is worth noting that effective management of WS in neonates requires prompt identification and treatment of associated complications.

PAX3 mutation suppress otic progenitors proliferation and induce apoptosis by inhibiting WNT1/β-catenin signaling pathway in WS1 patient iPSC-derived inner ear organoids

Waardenburg syndrome type 1 (WS1) is a hereditary disease mainly characterized by sensorineural hearing loss, dystopia canthorum, and pigmentary defects. To elucidate molecular mechanisms underlying PAX3-associated hearing loss, we developed inner ear organoids model using induced pluripotent stem cells (iPSCs) derived from WS1 patient and healthy individual. Our results revealed a significant reduction in the size of inner ear organoids, accompanied by an increased level of apoptosis in organoids derived from WS1 patient-iPSCs carrying PAX3 c.214A > G. Transcriptome profiling analysis by RNA-seq indicated that inner ear organoids from WS1 patients were associated with suppression of inner ear development and WNT signaling pathway. Furthermore, the upregulation of the WNT1/β-catenin pathway which was achieved through the correction of PAX3 isogenic mutant iPSCs using CRISPR/Cas9, contributed to an increased size of inner ear organoids and a reduction in apoptosis. Together, our results provide insight into the underlying mechanisms of hearing loss in WS.

Identification of two variants in PAX3 and FBN1 in a Chinese family with Waardenburg and Marfan syndrome via whole exome sequencing

Both Warrensburg (WS) and Marfan syndrome (MFS) can impair the vision. Here, we recruited a Chinese family consisting of two WS affected individuals (II:1 and III:3) and five MFS affected individuals( I:1, II:2, III:1, III:2, and III:5) as well as one suspected MFS individual (II:4). Using whole exome sequencing (WES) and subsequent PCR-Sanger sequencing, we identified one novel heterozygous variant NM_000438 (PAX3) c.208 T > C, (p.Cys70Arg) from individuals with WS and one previous reported variant NM_000138 (FBN1) c.2740 T > A, (p.Cys914Ser) from individuals with MFS and co-segregated with the diseases. Real-time PCR and Western blot assay showed that, compared to their wild-type, both mRNAs and proteins of  PAX3 and FBN1 mutants reduced in HKE293T cells. Together, our study identified two disease-causing variants in a same Chinese family with WS and MFS, and confirmed their damaged effects on their genes' expression. Therefore, those findings expand the mutation spectrum of PAX3 and provide a new perspective for the potential therapy.