SOX3 duplication in a boy with 46,XX ovotesticular disorder of sex development and his 46,XX sister with atypical genitalia: Probable germline mosaicism

Ovotesticular disorders of sex development (OT-DSD) are characterized by ovarian follicles and seminiferous tubules in the same individual, with a wide range of atypical genitalia. We report on two sibs with atypical genitalia and SRY-negative 46,XX DSD, OT-DSD was confirmed only in the boy, while the girl had bilateral ovaries. Chromosome microarray analysis (CMA) showed a 737-kb duplication at Xq27.1 including the entire SOX3 gene in both sibs, which was confirmed by quantitative real time PCR. Also, X chromosome inactivation assay showed random inactivation in both sibs. Whole exome sequencing revealed no pathogenic or likely pathogenic variant. CMA of the parents showed normal results for both, suggesting that germline mosaicism could be the reason of recurrence of this duplication in the siblings. Our results support a pathogenic role of SOX3 overexpression in 46,XX subjects leading to variable DSD phenotypes.

The 46, XX Ovotesticular Disorder of Sex Development With Xq27.1q27.2 Duplication Involving the SOX3 Gene: A Rare Case Report and Literature Review

Background: Very few reports are available on human XX ovotesticular disorder of sex development involving SOX3 gene duplication. Here we aim to present a rare case of SOX3 gene duplication in a person from the Chinese population who exhibits XX ovotesticular disorder of sex development. Case Presentation: A 7-year-old Chinese individual from Fujian province in Southeast China was recruited. The patient presented 46, XX karyotype, absence of sex-determining region Y, and was diagnosed with XX ovotesticular disorder of sex development. Furthermore, SNP array analysis demonstrated that the patient had a 2.2-Mb duplication in the Xq27.1q27.2 region (arr[hg19]Xq27.1q27.2:139,499,778-141,777,782) involving the SOX3 gene. Additionally, no SOX3 duplication was observed in the parents or the sibling, who displayed none of the clinical features. Conclusion: We identified the first case of SOX3 duplication in a Chinese individual who exhibits ovotesticular disorder of sex development. Our study strengthens the link between the SOX3 duplication and XX ovotesticular disorder of sex development and indicates that SOX3 is the evolutionary antecedent of sex-determining region Y.

Xq27.1 Duplication Encompassing SOX3: Variable Phenotype and Smallest Duplication Associated with Hypopituitarism to Date - A Large Case Series of Unrelated Patients and a Literature Review

BACKGROUND

Xq27.1 duplication encompassing SOX3 has been implicated in the aetiology of X-linked hypopituitarism associated with intellectual disability and neural tube defects. We describe the largest case series to date of 5 unrelated patients with SOX3 duplication with a variable clinical phenotype, including the smallest reported SOX3 duplication.

CASE REPORTS

Five male patients who presented with congenital hypopituitarism (CH) were identified to have Xq27.1 duplication encompassing SOX3. The size of the duplication ranged from 323.8 kb to 11 Mb. The duplication was maternally inherited or de novo in 2 patients each (and of unknown inheritance in 1 patient). The age at presentation was variable. Three patients had multiple pituitary hormone deficiencies, whereas 2 patients had isolated growth hormone deficiency. All patients had micropenis and/or small undescended testes. Structural pituitary and/or other midline cranial abnormalities (callosal hypogenesis/absence of the septum pellucidum) were present in all patients. Two patients had a neural tube defect in addition to CH.

CONCLUSIONS

This is the largest series reported to date of unrelated patients with CH in association with Xq27.1 duplication encompassing SOX3. The clinical phenotype is variable, which may be due to genetic redundancy or other unknown aetiological factors. We have expanded the phenotypic spectrum through description of the smallest Xq27.1 duplication (323.8 kb) with CH reported to date, as well as a second family with CH and a neural tube defect.

Marked phenotypic variable expression among brothers with duplication of Xq27.1 involving the SOX3 gene

We describe four phenotypically different brothers who share the same microduplication of Xq27.1, which contains the SOX3 gene. SOX3 mutations have been associated with growth hormone deficiency, variable degrees of additional pituitary hormone deficiencies, and mental retardation. SOX3 also appears to play an important role in pharyngeal arch segmentation that gives rise to craniofacial structures. While these four brothers have inherited the same mutation, they manifest a spectrum of phenotypes, ranging from complete, multiple pituitary hormone deficiencies to no apparent pituitary hormone deficiency with or without craniopharyngeal/facial dysmorphisms. We look to the literature to provide putative explanations for the variable expression of the brothers' shared SOX3 mutation.