DiagnosisClinical Diagnosis46,XX testicular disorder of sex development (46,XX testicular DSD) is diagnosed in individuals with:A 46,XX karyotype using conventional staining methodsMale external genitalia that range from normal to ambiguous (penoscrotal hypospadias with or without chordee)Two testiclesAzoospermiaNo evidence of Müllerian structuresTestingEndocrine testingEndocrine studies usually show hypergonadotropic hypogonadism secondary to testicular failure [Pérez-Palacios et al 1981].Basal serum concentration of LH and FSH are moderately elevated (normal range for LH: 1.5-9 mIU/mL in adult males; for FSH: 2.0-9.2 mIU/mL). Serum testosterone concentration is usually decreased, typically with serum testosterone concentration below 300 ng/dL in adults (normal range: 350-1030 ng/dL in adult males).Human chorionic gonadotrophin (hCG) stimulation test typically shows a low-to-subnormal testosterone response, with little or no elevation of serum testosterone concentration after IM injection of hCG.The hypothalamic-pituitary axis is preserved.GnRH stimulation testing shows a normal LH and FSH response.
Note: Such testing is not warranted for diagnosis.Cytogenetic studies. Routine cytogenetic studies demonstrate a 46,XX karyotype.Note: If Y chromosome material including SRY is located on the short arm of one X chromosome, it is usually too small to visualize without FISH (see Molecular Genetic Testing, Clinical testing).Histology. Testicular biopsy shows a decrease in size and number of seminiferous tubules, peritubular fibrosis, absence of germ cells, and hyperplasia of Leydig cells [de la Chapelle 1981].Note: Such testing is not warranted for diagnosis.Molecular Genetic TestingGene. SRY, the gene that encodes the sex-determining region Y protein, is the gene most commonly known to be associated with 46,XX testicular disorder of sex development (46,XX testicular DSD).Approximately 85% of individuals with XX testicular DSD are phenotypic males with unambiguous male genitalia at birth who are SRY positive and are not diagnosed until puberty fails to proceed normally [Queipo et al 2002, Zenteno-Ruiz et al 2001]. The remaining 15% of individuals with XX testicular DSD have genital ambiguity and are SRY positive in only a minority of cases [Zenteno-Ruiz et al 2001, Kusz et al 1999].Clinical testingFISH (fluorescence in situ hybridization). A commercially available FISH probe specific for SRY detects the presence of SRY in approximately 80% of individuals with 46,XX testicular DSD. The SRY-positive region is almost always on an X chromosome.PCR amplification of SRY may be used if FISH fails to detect the SRY region; PCR is more likely to detect a small amount of Y chromosome translocated on to the X chromosome and to detect the Y-chromosome material in an individual who is an XX-SRY positive/XX-SRY negative mosaic.Table 1. Summary of Molecular Genetic Testing Used in 46,XX Testicular Disorder of Sex DevelopmentView in own windowGene SymbolTest Method to Detect Presence of SRYSRY Detection Frequency by Test Method Test Availability Male GenitaliaNormalAmbiguousSRYFISH or PCR amplification80%RareClinical Testing StrategyTo confirm the diagnosis in a proband, the following algorithm is suggested:1.First, a conventional G-banded cytogenetic analysis should be performed to rule out other chromosome aberrations as well as to make the diagnosis of a normal female karyotype (46,XX).2.Next, FISH of an SRY probe to metaphase chromosomes should be performed to determine the nature of the rearrangement (SRY located on an X chromosome versus SRY located on an autosome). The inheritance patterns and genetic counseling issues are different for each one of these rearrangements.3.If SRY by FISH is not positive, PCR for SRY is the next step because PCR has greater sensitivity than FISH. Note, however, that cytogenetic analysis showing a 46,XX karyotype and a positive result by PCR for SRY sequence is not sufficient to determine the etiology and thus understand the inheritance pattern of this disorder.Prenatal diagnosis for pregnancies at risk for SRY-positive 46,XX testicular DSD requires conventional cytogenetic analysis and FISH of an SRY probe. If SRY by FISH is not positive, PCR for SRY may be performed. Genetically Related (Allelic) Disorders46,XX ovotesticular disorder of sex development (formerly known as “true hermaphrodism” and defined as presence of both testicular and ovarian tissue in an individual) is SRY positive in 10% of the cases, most commonly as a result of abnormal interchange between an X and Y chromosome resulting in translocation of SRY on to the X chromosome. Intrafamilial variability has been described, with SRY-negative 46,XX ovotesticular DSD and 46,XX testicular DSD within the same family [Ramos et al 1996].

Natural HistoryApproximately 80% of individuals with 46,XX testicular disorder of sex development (46,XX testicular DSD) present after puberty with normal pubic hair and normal penile size, but small testes, gynecomastia, and sterility resulting from azoospermia. The small testes are usually soft but may become firmer with age. Among these individuals, a minority have cryptorchidism (undescended testes) and/or anterior hypospadias (atypical urethral opening) [Boucekkine et al 1994]. Gender role and gender identity are reported as male for the common, unambiguous presentation, but systematic psychosexual assessment has not been performed on a significant number of individuals with 46,XX testicular DSD.Approximately 20% of individuals with 46,XX testicular DSD present at birth with ambiguous genitalia, typically penoscrotal hypospadias with or without chordee.46,XX testicular DSD is not associated with learning disorders or behavioral issues.The natural history of the 46,XX testicular DSD, if untreated, is similar to the typical consequences of testosterone deficiency:Low libido and possible erectile dysfunctionDecrease in secondary sexual characteristics, such as sparse body hair, infrequent need to shave, and reduced muscle massIncrease in fat mass with lower muscle strengthIncreased risk of osteopeniaIncreased risk of depressionSRY-positive 46,XX testicular DSD. Individuals with SRY-positive 46,XX testicular DSD typically present after puberty with the following:Shorter-than-average stature (mean height: 168.2 cm, compared to normal mean height: 173.5 cm) [de la Chapelle 1972]GynecomastiaSmall testesAzoospermiaIndividuals with SRY-positive 46,XX testicular DSD rarely present with atypical genitalia and are less likely than individuals with SRY-negative 46,XX testicular DSD to have gynecomastia [Ferguson-Smith et al 1990, Boucekkine et al 1994, Ergun-Longmire et al 2005].SRY-negative 46,XX testicular DSD. Individuals with SRY-negative 46,XX testicular DSD tend to present with ambiguous genitalia at birth, such as penoscrotal hypospadias and cryptorchidism, and, if untreated, almost always develop gynecomastia around the time of puberty.

Genotype-Phenotype CorrelationsIn 46,XX testicular DSD, the presence of SRY is often associated with the presence of normal male external genitalia, whereas the absence of SRY is more often associated with ambiguous genitalia [Grigorescu-Sido et al 2005]. However, genotype-phenotype correlation is not entirely reliable, because a small number of individuals with SRY-negative 46,XX testicular DSD have normal external genitalia [Vilain et al 1994, Zenteno et al 1997, Kolon et al 1998, Vernole et al 2000, Abusheikha et al 2001].

Differential DiagnosisSyndromic XX testicular DSDSyndromic cases of XX testicular DSD – characterized by palmoplantar keratosis and predisposition to squamous cell carcinoma of the skin – have been shown to be associated with mutations in R-Spondin 1 (RSPO1) [Parma et al 2006, Tomaselli et al 2008].46,XX testicular DSD may be associated with microphthalmia and linear skin defects when the X/Y abnormal interchange involves microdeletion of Xp [Kobayashi et al 1998, Kono et al 1999, Anguiano et al 2003].Isolated XX testicular DSDThe most common disorders in the differential diagnosis of 46,XX testicular DSD can be distinguished by karyotype and by FISH testing.Sex chromosome abnormalitiesKlinefelter syndrome. Klinefelter syndrome (47,XXY) and its variants (48,XXXY, 49,XXXXY, and 46XY/47,XXY mosaicism) are suspected in males with hypogonadism, small testes, and gynecomastia, all of which are also present in individuals with 46,XX testicular DSD. In contrast to 46,XX testicular DSD, Klinefelter syndrome is often characterized by normal or tall stature, speech delay, learning disorders, and behavioral problems.46,XX/46,XY. Individuals with 46,XX/46,XY chimerism may present as true hermaphrodites depending on the relative ratio of XX and XY cells; phenotypes may vary from normal male to normal female. In addition, evidence suggests that some XX individuals (whether males or true hermaphrodites) who are masculinized show some low-level hidden mosaicism for Y-chromosome derived sequences [Queipo et al 2002].45,X/46,XY. Affected individuals often present as male and may have short stature depending on the percentage of 45,X cells. Clinically, this presentation is indistinguishable from 46,XX testicular DSD; however, the chromosome findings are diagnostic. If the percentage of 45,X cells is very high, the phenotype is likely to be female with classic Turner syndrome.A mosaic duplication of 17q23.1-q24.3, including SOX9, was reported in one individual with 46,XX testicular DSD who was SRY negative [Huang et al 1999]. Duplication of SOX9 is thought to be responsible for the 46,XX testicular DSD in this individual. 46,XX ovotesticular DSD. Individuals with ovotesticular DSD are true hermaphrodites (i.e., they have both testicular and ovarian tissue either as an ovotestis or as an ovary and a testis), whereas individuals with 46,XX testicular DSD have only testicular tissue. The type of gonadal tissue in a true hermaphrodite can be established by gonadal biopsy. Possible bias of sampling of a gonadal biopsy that may miss the ovarian portion of the gonads needs to be considered. True hermaphrodites may have a uterus, or a hemi-uterus; individuals with 46,XX testicular DSD have no Müllerian structures. Endocrine investigations may reveal estrogen production in true hermaphrodites.21-hydroxylase deficiency causing congenital adrenal hyperplasia. This is the most common cause of congenital adrenal hyperplasia (CAH), a family of autosomal recessive disorders involving impaired synthesis of cortisol from cholesterol by the adrenal cortex. In 21-hydroxylase deficiency (21-OHD), excessive adrenal androgen biosynthesis results in virilization of all 46,XX females and salt wasting in some. Virilized females have ambiguous external genitalia and a normal uterus and ovaries. The diagnosis of 21-OHD is established by comparison of baseline and stimulated serum concentrations of the steroid precursor 17-hydroxy progesterone (17-OHP) by molecular genetic testing of the causative gene, CYP21A2. Inheritance is autosomal recessive.Prenatal exposure of a pregnancy with an XX karyotype to externally administered androgens such as danazol or endogenously produced androgens by the mother can cause virilization resulting in an infant with ambiguous genitalia that may look similar to those of a male with 46,XX testicular DSD and genital ambiguity.

ManagementEvaluations Following Initial DiagnosisTo establish the extent of disease in an individual diagnosed 46,XX testicular disorder of sex development (46,XX testicular DSD), the following evaluations are recommended:Assessment of mood, libido, energy, erectile function, acne, and breast tenderness and size by history and/or physical examinationDexascan to evaluate for osteopeniaTreatment of ManifestationsTestosterone replacement therapy. Management of individuals with 46,XX testicular DSD with testosterone deficiency is similar to that for other causes of testosterone deficiency. Physicians should check for the most current preparations and dosage recommendations before initiating testosterone replacement therapy.After age 14 years, low-dose testosterone therapy can be initiated. Note: If an individual has short stature and is eligible for growth hormone therapy, testosterone therapy should be either delayed or given at lower doses initially in order to maximize the growth potential.Testosterone enanthate is given IM every three to four weeks, starting at 100 mg and increasing by 50 mg every six months to 200-400 mg. Initial high doses of testosterone should be avoided to prevent priapism. The treatment should plateau, in adulthood, at the best possible dosage, typically between 50 and 400 mg every two to four weeks. Injection of testosterone enanthate is the preferred method of replacement therapy because of low cost and easy, at-home regulation of dosage; however, side effects include pain associated with injection and large variations of serum testosterone concentration between injections, resulting in a higher risk of mood swings. Alternative delivery systems that result in a more stable dosing include transdermal patches (scrotal and non-scrotal) and transdermal gels. Testosterone-containing gels, however, are associated with the risk of interpersonal transfer, which can be reduced by the use of new hydroalcoholic gels [Kuhnert et al 2005].Gynecomastia. Regression of gynecomastia may occur with testosterone replacement therapy. If it does not, and if it causes psychological distress to the individual, reduction mammoplasty can be offered.Osteopenia. Depending on the degree of osteopenia, treatment may include: calcium, exercise, vitamin D, biphosphonates, or calcitonin. Referral to an internist, pediatrician, or endocrinologist is recommended. Psychological support. Sensitivity is necessary when conveying information to individuals with 46,XX testicular DSD about the genetic cause and associated sterility of the disorder. This information must be presented in a manner that helps minimize psychological distress and to anticipate the need for further psychological assistance.SurveillanceMonitoring during testosterone replacement therapy should include:Evaluation of mood, libido, energy, erectile function, acne, and breast tenderness and sizeMeasurement of serum testosterone concentration at three-month intervals (prior to the next injection) to evaluate nadir testosterone concentrations. Concentrations lower than 200 ng/dL or higher than 500 ng/dL may require adjustment of total dose or frequency.In adults, digital rectal examination and measurement of prostate-specific antigen (PSA) prior to treatment and three, six, and 12 months after initiation of therapy to evaluate for the presence of an overt prostate cancer, which would be a contraindication to the treatment. Such testing should then be performed annually.For individuals on testosterone replacement therapy, evaluation of hematocrit at three, six, and 12 months, then annually because of risk of increased hematocrit with subsequent risk of hypoxia and sleep apneaLipid profile and liver function tests, as testosterone may alter lipid profile and liver functionBone mineral determination by bone densitometry (DEXA) once a year, if osteopenia has been diagnosedAgents/Circumstances to AvoidContraindications to testosterone replacement therapy include prostate cancer (known or suspected) and breast cancer.Oral androgens such as methyltestosterone and fluoxymesterone should not be given (especially for long-term therapy) because of liver toxicity.Evaluation of Relatives at RiskSee Genetic Counseling for issues related to testing of at-risk relatives for genetic counseling purposes.Therapies Under InvestigationSearch ClinicalTrials.gov for access to information on clinical studies for a wide range of diseases and conditions. Note: There may not be clinical trials for this disorder.

Molecular GeneticsInformation in the Molecular Genetics and OMIM tables may differ from that elsewhere in the GeneReview: tables may contain more recent information. —ED.Table A. 46,XX Testicular Disorder of Sex Development: Genes and DatabasesView in own windowGene SymbolChromosomal LocusProtein NameLocus SpecificHGMDSRYYp11​.31Sex-determining region Y proteinSRY homepage - Mendelian genesSRYData are compiled from the following standard references: gene symbol from HGNC; chromosomal locus, locus name, critical region, complementation group from OMIM; protein name from UniProt. For a description of databases (Locus Specific, HGMD) to which links are provided, click here.Table B. OMIM Entries for 46,XX Testicular Disorder of Sex Development (View All in OMIM) View in own window 40004546,XX SEX REVERSAL 1; SRXX1 480000SEX-DETERMINING REGION Y; SRYMolecular Genetic Pathogenesis46,XX testicular disorder of sex development (46,XX testicular DSD) can be explained in approximately 80% of individuals by the presence of a small Y-chromosome fragment, including SRY, in the genome. This is the result of an abnormal terminal X-Y exchange during paternal meiosis [Evans et al 1979, Andersson et al 1986]. This abnormal recombination involves highly homologous loci (recombination hotspots) on the sex-specific part of the X and Y chromosomes [Weil et al 1994]. One particular hotspot of recombination is located between PRKY, a protein kinase gene, and its X-linked homologue PRKX, and accounts for one third of all SRY-positive individuals with 46,XX testicular DSD [Schiebel et al 1997]. PRKY and PRKX are localized far from the pseudo-autosomal region where XY exchange normally occurs. The high homology between PRKY and PRKX explains the high frequency of abnormal recombination responsible for individuals with 46,XX testicular DSD.Normal allelic variants. SRY is an intronless gene encoding a 204-amino acid protein [Sinclair et al 1990]. The SRY promoter contains two GC-rich regions with several Sp1 sites.Pathologic allelic variants. 46,XX testicular DSD is caused by the translocation of a normal SRY allele onto an X chromosome. Note: Many abnormal allelic variants of SRY are observed in individuals with 46,XY disorder of sexual development (46,XY DSD) and 46,XY complete gonadal dysgenesis (46,XY CGD) but not in individuals with 46,XX testicular DSD.Normal gene product. SRY encodes a transcription factor that is a member of the HMG (high mobility group) box family. The HMG box confers the ability to bind and bend DNA. Two nuclear localization sequences, located on each side of the HMG box, are required for the nuclear translocation of SRY.Abnormal gene product. No abnormal product is observed in this disorder.