Waardenburg syndrome type 2 with a de novo variant of the SOX10 gene: a case report

BACKGROUND

Waardenburg syndrome type 2 (WS2) has been reported to be a rare hereditary disorder, which is distinguished by vivid blue eyes, varying degrees of hearing impairment, and abnormal pigment deposition in the skin and hair. Variants in the sex-determining region Y-box containing gene 10 (SOXl0) gene may cause congenital deafness and have been demonstrated to be important during the development of WS2.

METHODS

Complete clinical data of the proband and her family members (her parents and 2 sisters) was collected and physical examinations were performed in the hospital. The laboratory examination including hemoglobin, Coomb's test, urine protein, ENA, autoimmune hepatitis-related autoantibodies and ultrasonography were all conducted. We obtained the peripheral blood samples from all the participants and performed whole exome sequencing and sanger sequencing validation.

RESULTS

The present study identified a family of 5 members, and only the proband exhibited typical WS2. Beyond the characteristics of WS2, the proband also manifested absence of puberty. The proband and her younger sister manifested systemic lupus erythematosus (SLE). Whole exome sequencing revealed a de novo variant in the SOX10 gene. The variant c.175 C > T was located in exon 2 of the SOX10 gene, which is anticipated to result in early termination of protein translation.

CONCLUSION

The present study is the first to report a case of both WS2 and SLE, and the present findings may provide a new insight into WS2.

Association of autism spectrum disorder with Waardenburg syndrome in a toddler

Waardenburg syndrome is a rare genetic condition with an incidence of 1 in 212 000. The condition is classically associated with distinctive facial features, congenital hearing loss and pigmentary changes of the hair, iris and skin. There is a paucity of literature about the association of neurodevelopmental conditions with this syndrome. We present a toddler with Waardenburg syndrome type 1 who was referred to our service for developmental delay concerns. The child was diagnosed with the condition at birth, had distinctive facial features, but the hearing was normal. The child's father also shares a similar mutation. Following a multidisciplinary assessment, the child was diagnosed to have autism spectrum disorder with possible regression. We acknowledge that there may not be a causal relationship between autism spectrum and Waardenburg syndrome. However, this highlights the need for developmental surveillance among children diagnosed with Waardenburg syndrome and to consider its association with neurodevelopmental conditions.

Clinical manifestations and novel pathogenic variants in SOX10 in eight Danish probands with Waardenburg syndrome

The SRY-related HMG box gene 10 (SOX10), located on 22q13.1, encodes a member of the SOX family of transcription factors involved in the regulation of embryonic development and in the determination of cell fate and differentiation. SOX10 is one of the six causal genes for Waardenburg syndrome, which is a dominantly inherited auditory-pigmentary disorder characterized by sensorineural hearing impairment and abnormal pigmentation of the hair, skin and iris. Waardenburg syndrome is categorized into four subtypes based on clinical features (WS1-WS4). Here we present eight families (eleven patients) harboring pathogenic variants in SOX10. The patients displayed both allelic and clinical variability: bilateral profound hearing impairment (11/11), malformations of the semicircular canals (5/11), motor skill developmental delay (5/11), pigmentary defects (3/11) and Hirschsprung's disease (3/11) were some of the clinical manifestations observed. The patients demonstrate a spectrum of pathogenic SOX10 variants, of which six were novel (c.267del, c.299_300insA, c.335T >C, c.366_376del, c.1160_1179dup, and exon 3-4 deletion), and two were previously reported (c.336G>A and c.422T>C). Six of the variants occurred de novo whereas two were dominantly inherited. The pathogenic SOX10 variants presented here add novel information to the allelic variability of Waardenburg syndrome and illustrate the considerable clinical heterogeneity.

Clinical manifestations of Waardenburg syndrome in a male adolescent in Mali, West Africa

Waardenburg syndrome (WS) is a genetic disorder of which there are four distinct types. These four types are differentiated by the physical defects which they produce. Presented here is the case of a 13-year-old boy with WS Type I who was observed and physically assessed in Mali, West Africa in 1969. His physical findings included a bright blue coloring to the irises of the eyes, profound sensorineural deafness, mutism, dystopia canthorum (lateral displacement of the inner canthi of the eyes), broad nasal root, bushy eyebrows, and scaphoid deformities of the supraorbital portions of the frontal bone. Because family members were not available for interviews or physical examinations, it was not possible to determine if this patient was suffering from a congenital form of the disorder or from a spontaneous mutation. Given the patient's then location in a remote rural area of Mali where electricity was absent, it was not possible to perform additional diagnostic tests. The patient described here is the first with WS in Mali, West Africa to have been medically observed and evaluated and later documented in the medical literature. A second case of the syndrome in Mali was described in the medical literature in 2011 in an 18-month-old infant who did not have sensorineural hearing loss, but who did have a bilateral cleft lip. An historical overview of WS is presented along with details concerning the characteristics of the four types of the disorder.