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CASE SERIES
Year : 2018  |  Volume : 3  |  Issue : 2  |  Page : 68-72

Androgen insensitivity syndrome: An experience of genetic analysis of a family from a tertiary center – Saudi Arabia


1 Department of Pediatrics, Security Forces Hospital, Riyadh, Saudi Arabia
2 King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
3 Department of Pediatrics, College of Medicine, Al-Imam Muhammad Ibn Saud Islamic University, Riyadh, Saudi Arabia

Date of Submission09-Nov-2018
Date of Acceptance11-Nov-2018
Date of Web Publication12-Dec-2018

Correspondence Address:
Dr. Abdullah Y Al-Faifi
Department of Pediatrics, Security Forces Hospital, Riyadh
Saudi Arabia
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijas.ijas_14_18

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  Abstract 


Androgen insensitivity syndrome (AIS) is a disorder of sex development caused by mutations in the gene encoding the androgen receptor (AR). It is characterized by 46 XY karyotype, bilateral testes, absent mullerian duct structure, and female appearing external genitalia. This is a hospital-based case series study which comprised three cases who were seen at the Security Forces Hospital, Riyadh, Saudi Arabia. Case notes, imaging, and laboratory investigations indicated AIS among the three cases, with no variable degrees of insensitivity ranging. All three cases were within the same family, and there were two cases who were carriers for the mutation. One of these cases had an affected daughter (case #3) mentioned above. The present study identified a certain mutation (p.Arg775Cys) in a Saudi family. The mutation provides insights into the molecular mechanism underlying complete AIS and expands on a number of mutational hot spots in the international AR mutation database, especially in our community. The extent of androgen insensitivity in 46 XY individuals is not rare in a community with a high prevalence of consanguineous marriages. A multidisciplinary team approach is essential for successful management. Furthermore, it will be useful in the future for prenatal diagnosis and genetic counseling.

Keywords: Clinical characteristic, complete androgen insensitivity syndrome, imaging, mutational analysis, structural analysis


How to cite this article:
Al-Faifi AY, Al Anazi1 MI, Jabari M, Al-Faris A, Al Sahabi I, Al-sayed M, Al-Shehri H. Androgen insensitivity syndrome: An experience of genetic analysis of a family from a tertiary center – Saudi Arabia. Imam J Appl Sci 2018;3:68-72

How to cite this URL:
Al-Faifi AY, Al Anazi1 MI, Jabari M, Al-Faris A, Al Sahabi I, Al-sayed M, Al-Shehri H. Androgen insensitivity syndrome: An experience of genetic analysis of a family from a tertiary center – Saudi Arabia. Imam J Appl Sci [serial online] 2018 [cited 2019 Jan 21];3:68-72. Available from: http://www.e-ijas.org/text.asp?2018/3/2/68/247318




  Introduction Top


Androgen insensitivity syndrome (AIS), previously known as testicular feminization, is an X-linked recessive condition that results in failure of normal masculinization of the external genitalia in chromosomally male individuals. Failure of virilization can be either complete or partial, depending on the amount of receptor function.[1],[2],[3],[4],[5],[6],[7],[8]

The main phenotypic characteristics of individuals with complete AIS (CAIS) are female external genitalia, a short, blind-ending vagina, absence of Wolffian duct-derived structures, absence of a prostate, development of gynecomastia, and the absence of public and axillary hair. Testosterone levels are usually elevated at the time of puberty, while elevated luteinizing hormone (LH) levels are also found. In the partial AIS (PAIS), several different phenotypes are evident, ranging from individuals with predominantly a female appearance to persons with ambiguous genitalia, or individuals with a predominantly male phenotype. At puberty, elevated LH, testosterone, and estradiol levels are observed. Phenotypic variation between individuals in different families has been described for several mutations.[9],[10],[11],[12]

The androgen receptor (AR) gene is located on the X-chromosome at Xq11--12 and codes for a protein with a molecular mass of approximately 110 kDa. In the AR gene, four different types of mutations have been detected in DNA from individuals with AIS-(I) single point mutations resulting in amino acid substitutions or premature stop codons; (II) nucleotide insertions or deletions most often leading to a frameshift and premature termination; (III) complete or partial gene deletions; and (IV) intronic mutations in either splice donor or acceptor sites, which affect the splicing of AR RNA. The basic etioleogy is a loss-of-function mutation in the AR gene. Over 1,000 mutations have been described. Internationally, the incidence of the disease is appropriately one case per 20,400 live born males.[13],[14]

In this report, we describe our 3-year experience (2015–2017) at Security Forces Hospital (SFH), which is a major tertiary center, in Riyadh City, Saudi Arabia.


  Case Series Top


This study included a family which presented to the Endocrine and Clinical Genetic Service, at the SFH, Riyadh, Saudi Arabia over a 3 years' period (2015–2017). The SFH is one of the main referral hospitals in the central Saudi Arabia. The hospital provides primary, secondary, and tertiary health-care services for the local population and also receives patients' referrals from all over the country. Reviewing the clinical notes of patients, the diagnosis of androgen insensitivity was done retrospectively. The medical history and clinical examination were also reviewed. The appropriate diagnosis was based on the radiological and genetic evaluation. Genetic studies were carried out in this family by karyotype and targeted exome sequencing of the AR gene.

Test methods

Using genomic DNA obtained from a venous blood sample in ethylenediaminetetraacetic acid (buccal kits are not accepted for this test), the coding sequence of the AR gene (exons 1–8) and flanking splice sites were polymerase chain reaction (PCR) amplified and bi-directional sequence analysis was performed.

Approach

Using patient genomic DNA, we sequenced the indicated gene region(s). We then aligned and compared the patient's sequences with the reference sequences. All differences from the reference sequences (sequence variants) were assigned to one of five interpretation categories per ACMG Guidelines.[15] All sequence variants are reported below.

PCR was used to amplify the indicated exons plus additional flanking noncoding sequence. After cleaning of the PCR products, cycle sequencing was carried out using the ABI Big Dye Terminator version 3.1 kit (Thermo Fisher Scientific, Waltham, MA, USA). Products were resolved by electrophoresis on an ABI 3 730 × 1 capillary sequencer. In most cases, sequencing was performed in both forward and reverse directions; in some cases, sequencing was performed twice in either the forward or reverse directions. In nearly all cases, the full coding region of each exon as well as 20 bases of noncoding DNA flanking the exon is sequenced.

All patients were managed by an experienced multidisciplinary team constituting of a pediatric endocrinologist, neonatologist, geneticist, psychologist, and a pediatric surgeon or urologist. Ethical approval for this study was obtained from the Institutional Review Board at the SFH.


  Results Top


Case #1

A 13-year-old single virgin female was referred to our hospital with inguinal hernia bilaterally. On examination, her vitals were stable, her height was 175 cm, and her weight was 75 kg. Her breasts were well developed, and axillary and pubic hair were sparse.

The patient was referred to our hospital for further evaluation during her preoperative preparation for hernia operation.

Laboratory investigations revealed the following: serum follicle stimulating hormone = 62 IU/L, LH = 36 IU/L, estradiol = 15 pg/ml, and testosterone = 3.6 ng/dl. Ultrasound examination revealed the absence of female internal genitalia. Magnetic resonance imaging (MRI) exam confirmed the absence of feminine internal genitalia with oval cystic structures distal to the external inguinal ring about 2.6 and 2.8 cm in maximum dimensions which are features of ovaries with both normal kidneys.

Detailed magnetic resonance imaging findings

Atrophic vagina was noted, no uterus, with only rudimentary cervix that can be seen. There was elongated soft-tissue structure in the right side of the pelvis medial to the external iliac vessels, measuring 5.5 cm × 2.6 cm × 2.0 cm, with a small cyst at the superior portion, consistent with the deformed ovary. There was an elongated structure with multiple internal small cysts in the right side of pelvis medial to the external iliac vessels, measuring 4.8 cm × 1.7 cm × 1.5 cm, consistent with the right ovary. Normal rectum and urinary bladder outline. No pelvic mass lesion or lymphadenopathy seen.

This patient was referred to the Endocrine and Genetic Service. She had a male karyotype (XY), but normal female external genitalia and a blind-pouch vagina. Genetic analysis was done for this patient by doing full AR gene analysis. The patient was hemizygous in the AR gene for a variant designated c.2323C>T, which is predicted to result in the amino acid substitution p. Arg775Cys. This variant has been reported to be pathogenic for CAIS.

The patient was referred to the Urology Department for bilateral gonadectomy. Then, the patient was planned for hormonal substitution with estrogens.

Case #2

A 17-year-old female visited our clinic after the mutation found in her young sister (case #1). This case was complaining of primary amenorrhea. She was found to be a male karyotype, but with normal female external genitalia and a vagina of normal size and depth. The patient had a normal height, weight, and breast development, with very subtle axillary and pubic hair.

She was followed up at our department after finding the pathogenic mutation in her sister (case #1). MRI examination confirmed a testicle in the deep inguinal ring on both sides and cysts adjacent to them. The uterus, cervix, and  Fallopian tube More Detailss were absent, while the external genitalia and vagina had a normal appearance.

The patient was planned for gonadectomy. Then, she was planned for hormonal substitution with estrogens. We did for her target mutation analysis which showed positive results, similar to her sister having, hemizygous in the AR gene for a variant designated c.2323C>T, which is predicted to result in the amino acid substitution p. Arg775Cys. This variant has been reported to be pathogenic for CAIS.

Case #3

This patient was 3-year-old. She was born at full term by spontaneous vaginal delivery weighing 2.67 Kg. Both antenatal and postnatal courses were uneventful. She was the first child born to her parents. There was consanguinity with significant family history, in particular on the maternal side. Physical examination during the neonatal period revealed a normal female external genitalia.

Ultrasonography showed the presence of an infantile vagina with absent uterus, a structure suspected to be an ovary over the left side and the absence of fallopian tubes. The diagnosis of CAIS was suspected because of the significant family history and her mother was found to be a carrier for the mutation running on her family.

Blood for karyotype was taken. Results showed that she was XY. Then target mutation was done for her, as her mother was a carrier for androgen receptor mutation and the result came with hemizygous in the AR gene for a variant designated c.2323C>T, which is predicted to result in the amino acid substitution p. Arg775Cys. This variant has been reported to be pathogenic for CAIS.

Carrier testing was done for other siblings, which started by karyotyping and doing target mutation analysis. They were all found to be with normal karyotype, and none of them were carrying p. Arg775Cys mutation.


  Discussion Top


AIS is a genetic condition. In an individual with complete AIS and karyotype 46 XY, testes develop during gestation, with the production of Mullerian inhibiting hormone (MIH) and testosterone. MIH causes the regression of fetal Mullerian ducts. However, due to the failure to respond to testosterone, genitals differentiate in the female rather than the male pattern. Thus, the newborn infant has genital of normal female appearance, undescended, or partially descended testes. While in the partial form, the variable ambiguity of the genitalia is encountered. The condition is not that rare in communities with a high prevalence of consanguineous mating,[16] including Saudi Arabia.

The diseases have variable presentations from a normal female genitalia with 46 XY karyotype, through variable genital ambiguity, to delayed puberty in a normal looking female individuals, or an infertile male syndrome. Patients with the syndrome frequently have no pubic or axillary hair. A multidisciplinary team approach is needed to ensure better prognosis.[17]

An experienced pediatric surgeon or urologist is needed, either for genital penile reconstruction or vaginoplasty. The pediatric radiologist plays an important role in delineating the various internal structures and testes. At the time of diagnosis AIS, whether complete or partial, imaging should be ordered to evaluate the internal genitalia and location of the gonads. Ultrasound remains the best choice. However, MRI is the study of choice for evaluation as it provides more tissue characterization and detection of intra-abdominal gonads, but it most costly and least accessible.[18]

Patients with complete androgen insensitivity lack response to testosterone and therefore should be raised as females. It is advisable to remove the gonads at the time of diagnosis rather than wait until puberty, to avoid the adverse effects of testosterone on the neurons and to minimize the risk of the development of gonadoblastoma. The availability of estrogen replacement therapy allows gender re-assignment in these cases. However, the use of estrogen replacement therapy was debated recently. It has been suggested that the removal of gonads should be deferred until puberty to allow for estrogen formation. On the other hand, in cases where genetic male demonstrates any appreciable response to exogenous stimulation, a testosterone treatment of short duration might indicate the degree of masculinization achievable at puberty and facilitate the decision to raise such an individual as a male.[19],[20]

A pedigree analysis and a molecular study using PCR and DNA sequencing clarified each female family member's AR status and revealed a mutation consisting of the deletion of exon 2 and surrounding introns of the AR gene. Based on the relative nucleotide positions, these results were interpreted in the context of clinical findings, family history, and other laboratory data, and genetic analysis done for all members of this family to find out carrying status among them [Figure 1].
Figure 1: Family pedigree for the affected family

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This family having pathogenic mutation running, three cases hemizygous and two cases were carriers for that mutation. This patient was hemizygous in the AR gene for a variant designated c.2323C>T, which is predicted to result in the amino acid substitution p. Arg775Cys. This variant has been reported to be pathogenic for CAIS.

Pathogenic variants in the AR gene are the most common cause of AIS. To date, over 1,000 pathogenic variants have been described throughout the AR gene.[21] Nonsense and frameshift pathogenic variants cause CAIS, while weaker pathogenic variants, such as missense and regulatory (i.e., those in the promoter, introns, and 3' untranslated region) variants, cause more variable symptoms and PAIS. Importantly, all documented AR pathogenic variants, and their respective phenotype can be found in the AR Gene Mutations Database (ARDB, http://androgendb.mcgill.ca/), making it possible for physicians and genetic counselors to offer a statistically relevant phenotype prognosis for most identified pathogenic variants.

The AR gene is located on the X chromosome. Therefore, in most cases (60%), the pattern of inheritance is X-linked recessive. However, an apparently high mutation rate within the AR gene also results in relatively frequent occurrence (40%) of de novo pathogenic variants and somatic mosaicism.[22] Identifying patients with de novo pathogenic variants and somatic mosaicism has important consequences for sex assignment and genetic counseling. Pathogenic variants in AR have been detected in 46, XY females. However, 46, XX carrier females are often unaffected.[23]

Reviewing relevant literature, it was realized that there are only two published studies in Saudi Arabia that were conducted on patients with AIS.[17],[24] However, genetic analysis was not performed in any. Therefore, to the best of our knowledge, this study is the first report that discussed genetic and mutation analysis in detail.


  Conclusions Top


AR gene mutations cause a wide spectrum of disorders. The extent of androgen insensitivity in 46 XY individuals is not rare in a community with a high prevalence of consanguineous marriages. Early diagnosis is essential for gender assignment and further management, family counseling, and prenatal diagnosis. A multidisciplinary team approach is essential for successful management.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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