Small Indels in the Androgen Receptor Gene: Phenotype Implications and Mechanisms of Mutagenesis.

CONTEXT: Despite high abundance of small indels in human genomes, their precise roles and underlying mechanisms of mutagenesis in Mendelian disorders require further investigation. OBJECTIVE: To profile the distribution, functional implications, and mechanisms of small indels in the androgen receptor (AR) gene in individuals with androgen insensitivity syndrome (AIS). METHODS: We conducted a systematic review of previously reported indels within the coding region of the AR gene, including 3 novel indels. Distribution throughout the AR coding region was examined and compared with genomic population data. Additionally, we assessed their impact on the AIS phenotype and investigated potential mechanisms driving their occurrence. RESULTS: A total of 82 indels in AIS were included. Notably, all frameshift indels exhibited complete AIS. The distribution of indels across the AR gene showed a predominance in the N-terminal domain, most leading to frameshift mutations. Small deletions accounted for 59.7%. Most indels occurred in nonrepetitive sequences, with 15.8% situated within triplet regions. Gene burden analysis demonstrated significant enrichment of frameshift indels in AIS compared with controls (P < .00001), and deletions were overrepresented in AIS (P < .00001). CONCLUSION: Our findings underscore a robust genotype-phenotype relationship regarding small indels in the AR gene in AIS, with a vast majority presenting complete AIS. Triplet regions and homopolymeric runs emerged as prone loci for small indels within the AR. Most were frameshift indels, with polymerase slippage potentially explaining half of AR indel occurrences. Complex frameshift indels exhibited association with palindromic runs. These discoveries advance understanding of the genetic basis of AIS and shed light on potential mechanisms underlying pathogenic small indel events.

So, and if it is not congenital adrenal hyperplasia? Addressing an undiagnosed case of genital ambiguity.

BACKGROUND: The Congenital Adrenal Hyperplasia due to 21 hydroxylase deficiency is the most common cause of genital ambiguity in persons with XX sexual chromosomes. Genital ambiguity among persons with XY sexual chromosomes comprises diverse and rare etiologies. The deficiency of 17-beta-hydroxysteroid dehydrogenase type 3 enzyme (HSD17B3) is a rare autosomal recessive disorder due to functionally altered variants of the HSD17B3 gene. In this disorder/difference of sex development, the conversion of androstenedione into testosterone is impaired. The appearance of external genitalia of 46,XY individuals varies from typically male to almost female. CASE PRESENTATION: We report on a child presenting severe ambiguous genitalia. Due to access constraints, specialized care did not start until the child was 10 months old. Parents are consanguineous and were born in an area of high isonymy that is a cluster for rare recessive diseases. A new homozygous missense variant c.785G > T was found in exon 10 of the HSD17B3 gene. CONCLUSIONS: Researchers-clinicians and researchers-researchers collaborative efforts to elucidate the genetic basis of this disease were critical since this etiologic investigation is not available through the public health system. This case exemplifies the families' pilgrimage in cases of genital ambiguity due to a rare genetic condition. Recognizing the etiology was the baseline to provide information on prognosis and treatment options, and to shelter family and child doubts and hopes in order to better support their decisions.

Profile of patients with genitourinary anomalies treated in a clinical genetics service in the Brazilian unified health system / Perfil de pacientes com anormalidades geniturinárias atendidos em serviço de genética clínica no sistema único de saúde

To describe the profile of patients with genitourinary abnormalities treated at a tertiary hospital genetics service. Methods: Cross-sectional study of 1068 medical records of patients treated between April/2008 and August/2014. A total of 115 cases suggestive of genitourinary anomalies were selected, regardless of age. A standardized clinical protocol was used, as well as karyotype, hormone levels and genitourinary ultrasound for basic evaluation. Laparoscopy, gonadal biopsy and molecular studies were performed in specific cases. Patients with genitourinary malformations were classified as genitourinary anomalies (GUA), whereas the others, as Disorders of Sex Differentiation (DSD). Chi-square, Fisher and Kruskal–Wallis tests were used for statistical analysis and comparison between groups. Results: 80 subjects met the inclusion criteria, 91% with DSD and 9% with isolated/syndromic GUA. The age was younger in the GUA group (p<0.02), but these groups did not differ regarding external and internal genitalia, as well as karyotype. Karyotype 46,XY was verified in 55% and chromosomal aberrations in 17.5% of cases. Ambiguous genitalia occurred in 45%, predominantly in 46,XX patients (p<0.006). Disorders of Gonadal Differentiation accounted for 25% and congenital adrenal hyperplasia, for 17.5% of the sample. Consanguinity occurred in 16%, recurrence in 12%, lack of birth certificate in 20% and interrupted follow-up in 31% of cases. Conclusions: Patients with DSD predominated. Ambiguous genitalia and abnormal sexual differentiation were more frequent among infants and prepubertal individuals. Congenital adrenal hyperplasia was the most prevalent nosology. Younger patients were more common in the GUA group. Abandonment and lower frequency of birth certificate occurred in patients with ambiguous or malformed genitalia. These characteristics corroborate the literature and show the biopsychosocial impact of genitourinary anomalies.

Descrever o perfil de pacientes com anormalidades geniturinárias atendidos em serviço de genética de hospital terciário. Métodos: Estudo transversal de 1.068 prontuários de pacientes atendidos entre abril/2008 e agosto/2014. Foram selecionados 115 casos sugestivos de anomalias geniturinárias, independentemente da idade. Usaram-se protocolo clínico padronizado, cariótipo, hormônios e ultrassonografia geniturinária para avaliação básica. Laparoscopia, biopsia gonadal e estudos moleculares foram feitos em casos específicos. Pacientes com malformações geniturinárias foram classificados como defeitos geniturinários (DGU), os demais, como distúrbios da diferenciação do sexo (DDS). Usaram-se qui-quadrado, Fisher e Kruskal-Wallis para análise estatística e comparação entre os grupos. Resultados: Preencheram os critérios de inclusão 80 sujeitos, 91% com DDS e 9% com DGU isolados/sindrômicos. A idade foi menor no grupo DGU (p<0,02), mas esses grupos não diferiram quanto a genitália externa, interna e cariótipo. Verificou-se cariótipo 46,XY em 55% e aberrações cromossômicas em 17,5% dos casos. Ambiguidade genital ocorreu em 45%, predominou em pacientes 46,XX (p<0,006). Distúrbios da diferenciação gonadal representaram 25% e hiperplasia adrenal congênita; 17,5% da amostra. Consanguinidade ocorreu em 16%, recorrência em 12%, ausência de registro civil em 20% e interrupção do seguimento em 31% dos casos. Conclusões: Predominaram pacientes com DDS. Ambiguidade genital e diferenciação sexual anômala foram mais frequentes entre recém-nascidos e pré-púberes. Hiperplasia adrenal congênita foi a nosologia mais prevalente. Pacientes mais jovens pertenciam ao grupo DGU. Menor frequência de registro civil e abandono ocorreram em pacientes com genitália ambígua ou malformada. Essas características corroboram a literatura e evidenciam o impacto biopsicossocial das anormalidades geniturinárias.

[Profile of patients with genitourinary anomalies treated in a clinical genetics service in the Brazilian unified health system]. / Perfil de pacientes com anormalidades geniturinárias atendidos em serviço de genética clínica no sistema único de saúde.

OBJECTIVE: To describe the profile of patients with genitourinary abnormalities treated at a tertiary hospital genetics service. METHODS: Cross-sectional study of 1,068 medical records of patients treated between April/2008 and August/2014. A total of 115 cases suggestive of genitourinary anomalies were selected, regardless of age. A standardized clinical protocol was used, as well as karyotype, hormone levels and genitourinary ultrasound for basic evaluation. Laparoscopy, gonadal biopsy and molecular studies were performed in specific cases. Patients with genitourinary malformations were classified as genitourinary anomalies (GUA), whereas the others, as sex differentiation disorders (SDD). Chi-square, Fisher and Kruskal-Wallis tests were used for statistical analysis and comparison between groups. RESULTS: 80 subjects met the inclusion criteria, 91% with SDD and 9% with isolated/ syndromic GUA. The age was younger in the GUA group (p<0.02), but these groups did not differ regarding external and internal genitalia, as well as karyotype. Karyotype 46,XY was verified in 55% and chromosomal aberrations in 17.5% of cases. Ambiguous genitalia occurred in 45%, predominantly in 46,XX patients (p<0.006). Gonadal differentiation disorders accounted for 25% and congenital adrenal hyperplasia, for 17.5% of the sample. Consanguinity occurred in 16%, recurrence in 12%, lack of birth certificate in 20% and interrupted follow-up in 31% of cases. CONCLUSIONS: Patients with SDD predominated. Ambiguous genitalia and abnormal sexual differentiation were more frequent among infants and prepubertal individuals. Congenital adrenal hyperplasia was the most prevalent nosology. Younger patients were more common in the GUA group. Abandonment and lower frequency of birth certificate occurred in patients with ambiguous or malformed genitalia. These characteristics corroborate the literature and show the biopsychosocial impact of genitourinary anomalies.

The novel p.Cys65Tyr mutation in NR5A1 gene in three 46,XY siblings with normal testosterone levels and their mother with primary ovarian insufficiency.

BACKGROUND: Disorders of sex development (DSD) is the term used for congenital conditions in which development of chromosomal, gonadal, or phenotypic sex is atypical. Nuclear receptor subfamily 5, group A, member 1 gene (NR5A1) encodes steroidogenic factor 1 (SF1), a transcription factor that is involved in gonadal development and regulates adrenal steroidogenesis. Mutations in the NR5A1 gene may lead to different 46,XX or 46,XY DSD phenotypes with or without adrenal failure. We report a Brazilian family with a novel NR5A1 mutation causing ambiguous genitalia in 46,XY affected individuals without Müllerian derivatives and apparently normal Leydig function after birth and at puberty, respectively. Their mother, who is also heterozygous for the mutation, presents evidence of primary ovarian insufficiency. CASE PRESENTATION: Three siblings with 46,XY DSD, ambiguous genitalia and normal testosterone production were included in the study. Molecular analyses for AR, SRD5A2 genes did not reveal any mutation. However, NR5A2 sequence analysis indicated that all three siblings were heterozygous for the p.Cys65Tyr mutation which was inherited from their mother. In silico analysis was carried out to elucidate the role of the amino acid change on the protein function. After the mutation was identified, all sibs and the mother had been reevaluated. Basal hormone concentrations were normal except that ACTH levels were slightly elevated. After 1 mcg ACTH stimulation test, only the older sib showed subnormal cortisol response. CONCLUSION: The p.Cys65Tyr mutation located within the second zinc finger of DNA binding domain was considered deleterious upon analysis with predictive algorithms. The identification of heterozygous individuals with this novel mutation may bring additional knowledge on structural modifications that may influence NR5A1 DNA-binding ability, and may also contribute to genotype-phenotype correlations in DSD. The slightly elevated ACTH basal levels in all three patients with 46,XY DSD and the subnormal cortisol response after 1 mcg ACTH stimulation in the older sib indicate that a long-term follow-up for adrenal function is important for these patients. Our data reinforce that NR5A1 analysis must also be performed in 46,XY DSD patients with normal testosterone levels without AR mutations.

46,XX DSD and Antley-Bixler syndrome due to novel mutations in the cytochrome P450 oxidoreductase gene / DDS 46,XX e síndrome de Antley-Bixler causada por novas mutações no gene da enzima P450 oxidorredutase

Deficiency of the enzyme P450 oxidoreductase is a rare form of congenital adrenal hyperplasia with characteristics of combined and partial impairments in steroidogenic enzyme activities, as P450 oxidoreductase transfers electrons to CYP21A2, CYP17A1, and CYP19A1. It results in disorders of sex development and skeletal malformations similar to Antley-Bixley syndrome. We report the case of a 9-year-old girl who was born with virilized genitalia (Prader stage V), absence of palpable gonads, 46,XX karyotype, and hypergonadotropic hypogonadism. During the first year of life, ovarian cyst, partial adrenal insufficiency, and osteoarticular changes, such as mild craniosynostosis, carpal and tarsal synostosis, and limited forearm pronosupination were observed. Her mother presented severe virilization during pregnancy. The molecular analysis of P450 oxidoreductase gene revealed compound heterozygosis for the nonsense p.Arg223*, and the novel missense p.Met408Lys, inherited from the father and the mother, respectively. Arq Bras Endocrinol Metab. 2012;56(8):578-85.

A deficiência da enzima P450 oxidorredutase é uma forma rara de hiperplasia congênita da adrenal com características de inibição combinada e parcial de enzimas esteroidogênicas, pois a enzima P450 oxidorredutase participa da transferência de elétrons para as enzimas CYP21A2, CYP17A1 e CYP19A1. Essa deficiência causa um distúrbio do desenvolvimento do sexo e alterações esqueléticas semelhantes às da síndrome de Antley-Bixley. Relatamos o caso de uma menina, atualmente com 9 anos de idade, que apresentava ao nascimento genitais virilizados (Prader 5) sem gônadas palpáveis, com cariótipo 46,XX e hipogonadismo hipergonadotrófico. No primeiro ano de vida, foram observados cisto ovariano, insuficiência adrenal parcial e alterações osteoarticulares como leve craniossinostose, sinostose carpal e tarsal e limitação de pronossupinação dos membros superiores. Sua mãe apresentou intensa virilização durante a gestação. O estudo molecular do gene P450 oxidorredutase revelou a heterozigose composta das mutações nonsense p.Arg223* e da missense nova p.Met408Lys, herdadas do pai e da mãe, respectivamente. Arq Bras Endocrinol Metab. 2012;56(8):578-85.

46,XX DSD and Antley-Bixler syndrome due to novel mutations in the cytochrome P450 oxidoreductase gene.

Deficiency of the enzyme P450 oxidoreductase is a rare form of congenital adrenal hyperplasia with characteristics of combined and partial impairments in steroidogenic enzyme activities, as P450 oxidoreductase transfers electrons to CYP21A2, CYP17A1, and CYP19A1. It results in disorders of sex development and skeletal malformations similar to Antley-Bixley syndrome. We report the case of a 9-year-old girl who was born with virilized genitalia (Prader stage V), absence of palpable gonads, 46,XX karyotype, and hypergonadotropic hypogonadism. During the first year of life, ovarian cyst, partial adrenal insufficiency, and osteoarticular changes, such as mild craniosynostosis, carpal and tarsal synostosis, and limited forearm pronosupination were observed. Her mother presented severe virilization during pregnancy. The molecular analysis of P450 oxidoreductase gene revealed compound heterozygosis for the nonsense p.Arg223*, and the novel missense p.Met408Lys, inherited from the father and the mother, respectively.

Clinical and Laboratorial Features That May Differentiate 46,XY DSD due to Partial Androgen Insensitivity and 5α-Reductase Type 2 Deficiency.

The aim of this study was to search for clinical and laboratorial data in 46,XY patients with ambiguous genitalia (AG) and normal testosterone (T) synthesis that could help to distinguish partial androgen insensitivity syndrome (PAIS) from 5α-reductase type 2 deficiency (5α-RD2) and from cases without molecular defects in the AR and SRD5A2 genes. Fifty-eight patients (51 families) were included. Age at first evaluation, weight and height at birth, consanguinity, familial recurrence, severity of AG, penile length, LH, FSH, T, dihydrotestosterone (DHT), Δ4-androstenedione (Δ4), and T/DHT and T/Δ4 ratios were evaluated. The AR and SRD5A2 genes were sequenced in all cases. There were 9 cases (7 families) of 5α-RD2, 10 cases (5 families) of PAIS, and 39 patients had normal molecular analysis of SRD5A2 and AR genes. Age at first evaluation, birth weight and height, and T/DHT ratio were lower in the undetermined group, while penile length was higher in this group. Consanguinity was more frequent and severity of AG was higher in 5α-RD2 patients. Familial recurrence was more frequent in PAIS patients. Birth weight and height, consanguinity, familial recurrence, severity of AG, penile length, and T/DHT ratio may help the investigation of 46,XY patients with AG and normal T synthesis.

Molecular diagnosis of 5α-reductase type II deficiency in Brazilian siblings with 46,XY disorder of sex development.

The steroid 5α-reductase type II enzyme catalyzes the conversion of testosterone (T) to dihydrotestosterone (DHT), and its deficiency leads to undervirilization in 46,XY individuals, due to an impairment of this conversion in genital tissues. Molecular analysis in the steroid 5α-reductase type II gene (SRD5A2) was performed in two 46,XY female siblings. SRD5A2 gene sequencing revealed that the patients were homozygous for p.Gln126Arg missense mutation, which results from the CGA > CAA nucleotide substitution. The molecular result confirmed clinical diagnosis of 46,XY disorder of sex development (DSD) for the older sister and directed the investigation to other family members. Studies on SRD5A2 protein structure showed severe changes at NADPH binding region indicating that structural modeling analysis can be useful to evaluate the deleterious role of a mutation as causing 5α-reductase type II enzyme deficiency.