Familial 46,XY sex reversal without campomelic dysplasia caused by a deletion upstream of the SOX9 gene

Abstract

Background: 46,XY sex reversal is a rare disorder and familial cases are even more rare. The purpose of the present study was to determine the molecular basis for a family with three affected siblings who had 46,XY sex reversal.

Methods: DNA was extracted from three females with 46,XY sex reversal, two normal sisters, and both unaffected parents. All protein coding exons of the SRY and NR5A1 genes were subjected to PCR-based DNA sequencing. In addition, array comparative genomic hybridization was performed on DNA from all seven family members. A deletion was confirmed using quantitative polymerase chain reaction. Expression of SOX9 gene was quantified using reverse transcriptase polymerase chain reaction.

Results: A 349kb heterozygous deletion located 353kb upstream of the SOX9 gene on the long arm of chromosome 17 was discovered in the father and three affected siblings, but not in the mother. The expression of SOX9 was significantly decreased in the affected siblings. Two of three affected sisters had gonadoblastomas.

Conclusion: This is the first report of 46,XY sex reversal in three siblings who have a paternally inherited deletion upstream of SOX9 associated with reduced SOX9 mRNA expression.

Keywords: Gonadal dysgenesis; NR5A1; SOX9; SRY; XY sex reversal.

Figure 1

Family pedigree and the associated deletions and duplications identified by array CGH. 46,XY sex reversal patients are indicated by shaded squares. The arrow indicates the index case. Roman numerals indicate the different generations. The numbers within the square and circle in generation II indicate the number of brothers and sisters of the index case’s father.

Figure 2

(A) Gross Pathology of left gonad of III3 with 46,XY sex reversal. (B) Medium power view of the left dysgerminoma from III3 with the lymphocytic infiltrate characteristic of dysgerminoma/seminoma. (C) High power view, representative image of the 9 × 7 × 4 cm, almost completely necrotic left ovarian mass from III3. The cells are undergoing coagulative necrosis. Note the nucleolar prominence. (D) Right gonad from III3 with 0.4 cm focus of gonadoblastoma (White Arrow). Note nests of tumor cells composed of large germ cells with clear cytoplasm and smaller sex-cord type cells that surround the germ cells. Deposits of eosinophilic basement membrane material can be seen. Within this gonad, a 3 mm area of dygerminoma was also found (not shown).

Figure 2

(A) Gross Pathology of left gonad of III3 with 46,XY sex reversal. (B) Medium power view of the left dysgerminoma from III3 with the lymphocytic infiltrate characteristic of dysgerminoma/seminoma. (C) High power view, representative image of the 9 × 7 × 4 cm, almost completely necrotic left ovarian mass from III3. The cells are undergoing coagulative necrosis. Note the nucleolar prominence. (D) Right gonad from III3 with 0.4 cm focus of gonadoblastoma (White Arrow). Note nests of tumor cells composed of large germ cells with clear cytoplasm and smaller sex-cord type cells that surround the germ cells. Deposits of eosinophilic basement membrane material can be seen. Within this gonad, a 3 mm area of dygerminoma was also found (not shown).

Figure 3

A 349 kb deletion at 17q24.3 involving the father (II3) and three affected siblings (III1, III3, III5), but not the mother (II4) or the two 46,XX siblings (not shown).

Figure 4

Quantitative PCR performed on genomic DNA to confirm del17q24.3 in the father (II3) and the three affected siblings (III1, III3, III5) compared with a control male and 46,XX members of the family. See Materials and Methods for details.

Figure 5

RT-qPCR of SOX9 expression in the family and a control male. See Materials and Methods for details.

Figure 6

Schematic representation of chromosome 17 with the position of SOX9 indicated relative to the centromere and telomere. The position of the original ‘RevSex’ region described by Benko et al is indicated within the chromosome. The numbers indicate the distance (in kb) upstream from SOX9. The position and size of the deletion described by Fonseca et al is shown outside the chromosome, above the schematic. The position and size of the deletion described in the current study is indicated below and outside the representation of the chromosome. Finally, the position and size of the ‘revised RevSex’ region based on the new deletions is shown within the representation of the chromosome above the box indicating the original ‘RevSex’ region.