HORMONES 2011, 10(3):230-235
DOI: 
Case Report
Late diagnosis of 5alpha steroid-reductase deficiency due to IVS12A>G mutation of the SRD5a2 gene in an adolescent girl presented with primary amenorrhea
Nicos Skordis,1,2 Christos Shammas,2 Elisavet Efstathiou,1 Amalia Sertedaki,3 Vassos Neocleous,2 Leonidas Phylactou2

1Pediatric Endocrine Unit, Makarios Hospital, Nicosia, Cyprus, 2Department of Molecular Genetics Function & Therapy, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus, 3Unit of Endocrinology, Diabetes and Metabolism, First Department of Pediatrics, Athens University, Medical School, Athens, Greece

Abstract

BACKGROUND: The clinical spectrum of 5α-reductase deficiency, caused by mutations in the SRD5A2 gene, ranges from complete female appearance of the external genitalia at birth to nearly complete male phenotype. CASE REPORT: A 14-year-old girl presented with primary amenorrhea (PA) and lack of breast development. She was 173 cm in height, had an increased amount of pubic hair and clitoromegaly (3 cm), with a 4 cm blind vaginal pouch. Gonads were palpable in the inguinal canal bilaterally and no uterus was identified on ultrasound. Chromosomal analysis showed a 46,XY karyotype. The Testosterone/DHT ratio was high (16.5) and further increased to 29.4 after stimulation with hCG, thus favouring the diagnosis of 5α-reductase deficiency. Since the issue of gender change was not considered, gonadectomy was performed followed by successful feminisation with hormonal replacement therapy. GENETIC STUDIES: Molecular analysis of the SRD5A2 gene by DNA sequencing of all 5 exons revealed the presence of the splice mutation A>G at position -2 of the acceptor site of intron 1/exon 2 (IVS1-2A>G) in homozygosity. Both non-consanguineous parents were found to be heterozygotes for this mutation. CONCLUSIONS: Although rare, SRD5A2 gene defect should be suspected in any girl presenting with PA and virilisation at puberty. The IVS1-2A>G mutation of the SRD5A2 gene predominates in Greek-Cypriot patients with 5α-reductase deficiency and very likely reflects a founder effect.

Keywords

46,XY disorder of sex development (DSD), 5α-reductase, Male pseudohermaphroditism, SRD5A2 gene


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INTRODUCTION

Dihydrotestosterone (DHT) is essential for the normal development of male external genitalia. DHT is derived from testosterone (T) by a process catalysed by the membrane-bound steroid 5a-reductase enzyme. Impaired DHT synthesis caused by 5alpha steroid reductase deficiency (5α-reductase deficiency) can lead to incomplete masculinisation of the external genitalia in subjects with a 46,XY karyotype.1 The clinical spectrum of a 46,XY individual with 5α-reductase deficiency at birth can range from complete female appearance of the external genitalia to nearly complete male phenotype. Most patients, however, present with genital ambiguity and are diagnosed in infancy. At puberty 46,XY patients show virilisation without breast development, often accompanied by gender identity change, from female to male in individuals in whom gonads had not been removed.2-5

The enzyme steroid 5α-reductase exists as two isoforms, 5α-R type 1 and 5α-R type 2, which have a different expression pattern. Type 1 isoenzyme is encoded by the SRD5A1 gene located on chromosome 5 and expressed at low levels in the prostate, whereas type 2 isoenzyme is encoded by the SRD5A2 gene that maps on chromosome 2 and is expressed at high levels in the prostate and in many other androgen-sensitive tissues.6

5α-reductase deficiency is caused by mutations in the SRD5A2 gene, whereas the SRD5A1 gene has not been found to be mutated in this disease. To date, 54 different mutations of the SRD5A2 gene have been reported 42 of which are missense/nonsense mutations (http://www.hgmd.cf.ac.uk/ac/gene.php?gene=SRD5A2). Several SRD5A2 mutations have been identified in various populations, while others have only been described in specific ethnic groups. Given the significant advances in understanding the molecular basis of abnormal sexual development, it is important to integrate current knowledge to establish the exact diagnosis in any subject with defects in sexual differentiation.

Although most individuals with 5α-reductase deficiency are identified in the neonatal period because of ambiguous genitalia, some are misdiagnosed as androgen insensitivity syndrome, as they often present with the same clinical phenotype, while others escape recognition completely. The current report describes the identification of the IVS1-2A>G mutation of the SRD5A2 gene in homozygosity in an adolescent girl presented with primary amenorrhea (PA) and virilisation.

CASE PRESENTATION


A 14-year-old girl of non-consanguineous parents presented with PA and lack of breast development. She was 173 cm in height, obviously virilised with an increased amount of pubic hair extended to the inner thigh area and clitoromegaly (3 cm). She also had a deep voice and prominent Adam’s apple. Gonads were palpable in the inguinal canal bilaterally. She underwent a gynaecological examination which showed a 4 cm blind vaginal pouch. No uterus was identified on pelvic ultrasound.

LABORATORY INVESTIGATION AND RESULTS

Chromosomal analysis showed a normal male 46,XY karyotype. The diagnosis of 5α-reductase deficiency was suspected based on biochemical findings at base line and following hCG stimulation test (hCG 3000 Units daily for 3 consecutive days). As shown in Table 1 , the patient’s Testosterone to DHT ratio (T/DHT) was elevated before (16.6) and further increased after hCG stimulation (29.5). The diagnosis of 17β-HSD-3, which may have similar clinical presentation, seemed unlikely because of the normal response of androstenedione.

Molecular studies

The screening for the IVS1-2A>G mutation in our population previously reported showed a carrier rate of 0.98%, or 2 in 204 [95% Poisson confidence interval (CI), 0.12-3.54% and/or using the binomial CI, 0.12-3.5%].7

DNA sequencing of all five exons of the SRD5A2 gene was carried out in the patient and her parents, as previously described.8 Briefly, genomic DNA was subjected to PCR amplification with the forward primer 5’ gttaaggcgaaatggcagag 3’ and the reverse primer 5’acgaggtcattgcagtaggg 3’, which selectively amplify part of intron 1 and exon 2 of the SRD5A2 gene producing a fragment of 382 bp. For the detection of the IVS1-2A>G mutation at the splice junction intron 1/exon 2, BstNI restriction enzyme digest was performed. For confirmation of the identified IVS1-2A>G mutation, direct sequencing was also employed on an automated Beckman Coulter CEQ 2000 sequencer. The IVS1-2A>G mutation of SRD5A2 gene was identified in a homozygous state in our patient (Figure 1).




Figure 1. Partial sequence of the intron1/exon2 junction showing the A to G mutation at position -2 of the acceptor splice site. The mutation is homozygous in the patient. A normal control is added.

The diagnosis of SRD5A2 was confirmed by molecular studies as indicated above. The subsequent and difficult decision to be made was the possible gender change and consequent maintenance or removal of the gonads. Based on an extensive discussion, genetic counselling and psychological support of the parents, the issue of gender change at this critical age of the patient was not considered appropriate or acceptable. Therefore, gonadectomy was performed with no plastic surgery of the external genitalia at this stage. The patient was subsequently placed on hormonal replacement therapy and she was successfully feminised.

DISCUSSION

The present report describes the clinical and molecular characteristics of a 14-year-old virilised girl, who presented with PA and was finally diagnosed as a 46,XY individual with 5α-reductase deficiency. The typical clinical features in 46,XY males with 5α-reductase deficiency are generally those initially reported.4 Currently, the diagnosis of 5α-reductase deficiency is usually made in the newborn period because most affected individuals present with ambiguous genitalia.9 Some children, however, either escape diagnosis or they are misdiagnosed as having partial or complete androgen insensitivity syndrome. The application of molecular testing is a mandatory diagnostic tool for identifying the underlying cause, since biochemical findings in such cases can be misleading.7,10 The molecular diagnostic approach using genetic screening of the SRD5A2 gene permits diagnosis without the need of dynamic testing even in patients who had their testes removed.4 If the diagnosis is not made at an early age, the child begins to virilise rather than feminise at puberty if the gonads have not been removed. The clinical signs in the present case are those seen in affected individuals at puberty, namely enlargement of the phallus, virilisation, deepening of the voice, prominent Adam’s apple and absence of breast development.

The late diagnosis of affected males with 5α-reductase deficiency has been less commonly reported in recent studies compared to earlier publications, in which the majority of the 168 reported cases were diagnosed in infancy or childhood.4,5,8-36 Most affected subjects with 5α-reductase deficiency presented striking ambiguity of the genitalia with a clitoral-like phallus, severely bifid scrotum, pseudovaginal perineoscrotal hypospadias and a rudimentary prostate. More masculinised individuals lacked a separate vaginal opening or had a blind vaginal pouch which opened into the urethra. Others presented penile hypospadias or even penile urethra. When the genital ambiguity is not very obvious at birth, affected children are raised as females. With the onset of puberty the affected males have increased muscle mass and deepening of the voice.37

Following discussions and psychological support, the family did not wish a change to a male gender nor did they wish to address this delicate and frustrating issue. Most individuals raised as girls develop a male gender identity and male gender role in adolescence and early adulthood, possibly as a result of pre- and postnatal brain exposure to androgens.36,38 The virilisation at puberty is commonly associated with a change in gender role in affected individuals who are not diagnosed in infancy and are raised as girls. A significant number of affected individuals still live as females, although most patients develop a male gender identity in adolescence. The degree of virilisation of the external genitalia at birth does not seem to influence the prevalence of gender role changing. Several factors may determine whether these individuals who were raised as girls will make a switch after puberty. A possible biological factor is the severity of the mutation in terms of the in vivo enzyme deficiency, causing more or less (prenatal) exposure of the brain to androgens. Cultural or other environmental pressures have also been mentioned as potential determinants.

The dilemma of sex reassignment in the present case, where the issue of sexual orientation was purposely not raised, is similar to a previously reported case of an adolescent with 17β-HSD-3 deficiency raised as girl.39 In that particular case, despite the degree of virilisation of the girl, her manly dressing and behaviour and disturbed emotional status, the final decision following extensive and longtime psychological evaluation was not to proceed to gender change but perform gonadectomy and hormonal replacement therapy, which was obviously successful. Gender role changes are estimated to occur in more than 50% of cases with 5α-reductase deficiency and 17β-HSD-3.40 In these two entities the degree of external genital musculinisation at birth does not determine psychosexual outcome. Instead, a masculine appearance in childhood in association with masculine behaviour make a gender role change likely after the pubertal changes reinforce an already existing gender discomfort.

The mutation IVS1-2A>G of the present patient has also been identified in other Cypriot patients, most likely indicating a founder effect.41 Our study in the general population indicates that this is a common mutation in the Cyprus population with an estimated carrier frequency of 0.98%.7 This is further supported by the fact that this mutation has so far been reported at high frequency only in this geographic area. It is therefore speculated that this genetic defect is characteristic in the Eastern Mediterranean area. A study of eight patients from unrelated Turkish families with 5α-reductase deficiency revealed the presence of the p.L55Q mutation in six, a finding indicating the increased prevalence of this mutation (hot spot) in the Turkish population.17 In a large Lebanese pedigree, where all eight patients were born with unambiguous female genitalia, the same p.L55Q mutation in homozygosity was described.35 Other mutations found in Greek-Cypriot patients include p.P181L and p.R171S in compound heterozygosity with the IVS1-2A>G mutation.7

In conclusion, 5α-reductase deficiency, although rare, should be suspected in any girl presenting with PA and pubertal virilisation and established by molecular analysis of the SRD5A2 gene. In patients with 5α-reductase deficiency diagnosed so late, as is also the case with 17β-HSD-3, the management is highly problematic and requires extensive psychological evaluation and support of the patient and his family for the final decision of gender assignment as well a later on. To avoid these complications every effort must be made to establish the underlying molecular defect in every newborn with Disorder in Sexual Development.

Declaration of interest

The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.

Funding
This work was supported by the A.G. Leventis Foundation, Cyprus.

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Address for correspondence:
Nicos Skordis, MD, Pediatric Endocrine Unit, Dept of Paediatrics,
Nicosia 1474, Cyprus, Tel.: +357 22405000,
Fax: +357 22305072, e-mail: nskordis@cytanet.com.cy

Received 02-01-11, Revised 02-03-11, Accepted 22-04-11


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