46, XY gonadal dysgenesis: new SRY point mutation in two siblings with paternal germ line mosaicism

Stoppa‐Vaucher S, Ayabe T, Paquette J, Patey N, Francoeur D, Vuissoz J‐M, Deladoëy J, Samuels ME, Ogata T, Deal CL. 46, XY gonadal dysgenesis: new SRY point mutation in two siblings with paternal germ line mosaicism. Familial recurrence risks are poorly understood in cases of de novo mutations. In the event of parental germ line mosaicism, recurrence risks can be higher than generally appreciated, with implications for genetic counseling and clinical practice. In the course of treating a female with pubertal delay and hypergonadotropic hypogonadism, we identified a new missense mutation in the SRY gene, leading to somatic feminization of this karyotypically normal XY individual. We tested a younger sister despite a normal onset of puberty, who also possessed an XY karyotype and the same SRY mutation. Imaging studies in the sister revealed an ovarian tumor, which was removed. DNA from the father's blood possessed the wild type SRY sequence, and paternity testing was consistent with the given family structure. A brother was 46, XY with a wild type SRY sequence strongly suggesting paternal Y‐chromosome germline mosaicism for the mutation. In disorders of sexual development (DSDs), early diagnosis is critical for optimal psychological development of the affected patients. In this case, preventive karyotypic screening allowed early diagnosis of a gonadal tumor in the sibling prior to the age of normal puberty. Our results suggest that cytological or molecular diagnosis should be applied for siblings of an affected DSD individual.     

Novel candidate genes for 46,XY gonadal dysgenesis identified by a customized 1 M array-CGH platform

Half of all patients with a disorder of sex development (DSD) do not receive a specific molecular diagnosis. Comparative genomic hybridization (CGH) can detect copy number changes causing gene haploinsufficiency or over-expression that can lead to impaired gonadal development and gonadal DSD. The purpose of this study was to identify novel candidate genes for 46,XY gonadal dysgenesis (GD) using a customized 1 M array-CGH platform with whole-genome coverage and probe enrichment targeting 78 genes involved in sex development. Fourteen patients with 46,XY gonadal DSD were enrolled in the study. Nine individuals were analyzed by array CGH. All patients were included in a follow up sequencing study of candidate genes. Three novel candidate regions for 46,XY GD were identified in two patients. An interstitial duplication of the SUPT3H gene and a deletion of C2ORF80 were detected in a pair of affected siblings. Sequence analysis of these genes in all patients revealed no additional mutations. A large duplication highlighting PIP5K1B, PRKACG and FAM189A2 as candidates for 46,XY GD, were also detected. All five genes are expressed in testicular tissues, and one is shown to cause gonadal DSD in mice. However detailed functional information is lacking for these genes.     

46,XY disorder of sex development and developmental delay associated with a novel 9q33.3 microdeletion encompassing NR5A1

Steroidogenic factor 1 (SF1) is a nuclear receptor encoded by the NR5A1 gene. SF1 affects both sexual and adrenal development through the regulation of target gene expression. Genotypic male and female SF1 knockout mice have adrenal and gonadal agenesis with persistent Müllerian structures and early lethality. There have been several reports of NR5A1 mutations in individuals with 46,XY complete gonadal dysgenesis (CGD) or other disorders of sex development (DSD) with or without an adrenal phenotype. To date microdeletions involving NR5A1 have been reported in only two patients with DSDs.     

Novel homozygous mutations in Desert hedgehog gene in patients with 46,XY complete gonadal dysgenesis and prediction of its structural and functional implications by computational methods

Male to female sex reversal in patients with 46,XY karyotype results from the failure of development of testis which may be due to mutations in the SRY gene. Only 10–15% of cases of 46,XY gonadal dysgenesis are accounted for by different types of mutations in the SRY gene. Hence, majority of such patients may have mutations in other genes involved in the testicular differentiation pathway. Besides SRY, other autosomal and X-linked genes are also involved in sexual development during embryogenesis. We describe here the first report from India wherein, two cases of 46,XY complete gonadal dysgenesis that could be attributable to mutations in the Desert hedgehog (DHH) gene. The mutations found in these two patients were a homozygous deletion (c.271_273delGAG) that resulted in deletion of one amino acid (p.D90del) and a homozygous duplication (c.57–60dupAGCC) that resulted in premature termination resulting in non-functional DHH protein. The structure–function implications of the p.D90del mutation were predicted using computational tools. Structural studies on the p.D90del mutant revealed that the mutation could seriously perturb the interaction of DHH with its binding partners. This is the second report in literature showing homozygous mutation in cases with 46,XY complete gonadal dysgenesis.     

Embryonic testicular regression sequence: A part of the clinical spectrum of 46, XY gonadal dysgenesis

With the identification of the cystic fibrosis (CF) gene and its major mutations in 1989, there has been considerable debate among health professionals as to whether population-based carrier testing should be instituted. This paper presents the results of a survey to determine the attitudes of physicians and genetics professionals towards CF carrier testing. Factors associated with differences in attitudes also were examined. A questionnaire was mailed to primary care physicians and psychiatrists in 10 states who graduated from medical school between 1950 and 1985. For comparison, medical geneticists and genetic counselors in the same states also received the questionnaire. A total of 1,140 primary care physicians and psychiatrists (64.8%) and 280 medical geneticists and genetic counselors (79.1%) responded. Although 92% of respondents believed that a couple should be tested after asking about a test that detected 80% of carriers, only 43.9% of respondents believed such a test should be offered routinely. Those specialists most likely to have been involved in genetic services were most opposed to routine screening. The most important reason reported for opposition to routine screening was the consequences of an 80% detection rate. When presented with a hypothetical “error-free” test, 75.9% of respondents favored routine testing. Our findings suggest that there was little support for routinely offering the CF carrier test available at the time of this study among the physicians and professionals most involved in the provision of genetic services. © 1994 Wiley-Liss, Inc.     

No evidence of mutations in the follicle‐stimulating hormone receptor gene in Mexican women with 46,XX pure gonadal dysgenesis

In the ovary FSH is necessary for normal follicular development, binding to its receptor (FSHR) that pertains to the superfamily of G‐protein coupled receptors. In the FSHR gene, which consists of 10 exons, an homozygous mutation was reported in six Finnish families with gonadal dysgenesis; whereas two isolated French patients exhibited compound heterozygous mutations. Several groups, however, have searched for FSHR mutations, although in most cases the gene has been studied partially, not finding any genetic abnormalities in German, English, North American or Brazilian women. We performed direct sequencing of all 10 exons of the FSHR gene in seven sporadic patients and two sisters with 46,XX pure gonadal dysgenesis, to investigate the cause of their disorder. No heterozygous or homozygous mutant alleles were present in any of the patients. Although the number of patients evaluated was small, considering all the other previous reports, it seems that except in the Finnish population, the proportion of women with mutations in the encoding region of this gene is very low. Other possibilities for the presence of 46,XX gonadal dysgenesis, such as defects in the regulatory regions of the FSHR gene promoter, in the untranslated regions of exons 1 and 10, and within introns, or the existence of other genes likely to be important for normal ovarian function on the X chromosome or on autosomes, should be considered. In contrast with other studies, we did not find polymorphisms of the FSHR gene, indicating that apparently in Mexicans this gene is not highly polymorphic. © 2001 Wiley‐Liss, Inc.     

46,XX pure gonadal dysgenesis with growth hormone deficiency and impaired 3β-hydroxysteroid dehydrogenase activity

Patients with 46,XX pure gonadal dysgenesis generally are of normal stature and have less than usual amounts of pubic and axillary hair. We report on a patient who presented at age 11.9 years with short stature, absence of breast development, and excessive pubic hair. Her karyotype in leukocytes, fibroblasts, and streak gonad was 46,XX. The patient was diagnosed as having growth hormone deficiency. Elevated ACTH stimulated levels of 17-hydroxypregnenolone and dehydroepiandrosterone and elevated ACTH stimulated ratio of 17-hydroxypregnenolone to 17-hydroxyprogesterone suggested inadequate adrenal 3β-hydroxysteroid dehydrogenase activity. Treatment with growth hormone resulted in improvement in growth velocity and replacement with estrogen in feminization. We suggest that the finding of short stature in patients with 46, XX pure gonadal dysgenesis should not be attributed to the syndrome, but rather requires investigation for possible growth hormone deficiency. The poor growth of our patient prior to growth hormone replacement implies that dehydroepiandrosterone, unlike testosterone and estrogen, is ineffective in promoting linear growth in the absence of adequate growth hormone.     

Clinical and genetic analysis of MAPT, GRN, and C9orf72 genes in Korean patients with frontotemporal dementia

The hexanucleotide repeat expansion (GGGGCC) in chromosome 9 open-reading frame 72 (C9orf72) and mutations in the microtubule-associated protein tau (MAPT) and progranulin (GRN) genes are known to be associated with the main causes of familial or sporadic amyotrophic lateral sclerosis and frontotemporal dementia (FTD) in Western populations. These genetic abnormalities have rarely been studied in Asian FTD populations. We investigated the frequencies of mutations in MAPT and GRN and the C9orf72 abnormal expansion in 75 Korean FTD patients. Two novel missense variants of unknown significance in the MAPT and GRN were detected in each gene. However, neither abnormal C9orf72 expansion nor pathogenic MAPT or GRN mutation was found. Our findings indicate that MAPT, GRN, and C9orf72 mutations are rare causes of FTD in Korean patients.     

A rare case of 46, XX SRY-negative male with a ∼74-kb duplication in a region upstream of SOX9

The 46, XX male disorder of sex development (DSD) is a rare genetic condition. Here, we report the case of a 46, XX SRY-negative male with complete masculinization. The coding region and exon/intron boundaries of the DAX1, SOX9 and RSPO1 genes were sequenced, and no mutations were detected. Using whole genome array analysis and real-time PCR, we identified a ∼74-kb duplication in a region ∼510–584 kb upstream of SOX9 (chr17:69,533,305–69,606,825, hg19). Combined with the results of previous studies, the minimum critical region associated with gonadal development is a 67-kb region located 584–517 kb upstream of SOX9. The amplification of this region might lead to SOX9 overexpression, causing female-to-male sex reversal. Gonadal-specific enhancers in the region upstream of SOX9 may activate the SOX9 expression through long-range regulation, thus triggering testicular differentiation.     

Functional characterization of five NR5A1 gene mutations found in patients with 46,XY disorders of sex development

Steroidogenic factor‐1 (SF1), encoded by the NR5A1 gene, is a key regulator of steroidogenesis and reproductive development. NR5A1 mutations described in 46,XY patients with disorders of sex development (DSD) can be associated with a range of conditions of phenotypes; however, the genotype–phenotype correlation remains elusive in many cases. In the present study, we describe the impact of five NR5A1 variants (three novel: p.Arg39Cys, p.Ser32Asn, and p.Lys396Argfs*34; and two previously described: p.Cys65Tyr and p.Cys247*) on protein function, identified in seven patients with 46,XY DSD. In vitro functional analyses demonstrate that NR5A1 mutations impair protein functions and result in the DSD phenotype observed in our patients. Missense mutations in the DNA binding domain and the frameshift mutation p.Lys396Argfs*34 lead to both, markedly affected transactivation assays, and loss of DNA binding, whereas the mutation p.Cys247* retained partial transactivation capacity and the ability to bind a consensus SF1 responsive element. SF1 acts in a dose‐dependent manner and regulates a cascade of genes involved in the sex determination and steroidogenesis, but in most cases reported so far, still lead to a sufficient adrenal steroidogenesis and function, just like in our cases, in which heterozygous mutations are associated to 46,XY DSD with intact adrenal steroid biosynthesis.     

Surgically treated ovarian endometriosis association with BRCA1 and BRCA2 mutations

Endometriosis is associated with an increased risk of ovarian cancer. Few studies have also shown increased risk of breast cancer. BRCA1/2 mutations are linked to an increased risk of breast and ovarian cancers but their relation to endometriosis is unknown.     

Mutations in UBQLN2 and SIGMAR1 genes are rare in Korean patients with amyotrophic lateral sclerosis

Mutations in the UBQLN2 and SIGMAR1 genes were recently identified in X-linked dominant amyotrophic lateral sclerosis and/or frontotemporal dementia (ALS and/or FTD) and FTD and/or motor neuron disease, respectively. Subsequent studies, however, found that UBQLN2 mutations were rare, and the pathogenicity of SIGMAR1 mutation in FTD and/or motor neuron disease was controversial. In the present study, we analyzed mutations in the UBQLN2 and SIGMAR1 genes in a Korean cohort of 258 patients with familial ALS (n = 9) or sporadic (sALS; n = 258) ALS. One novel UBQLN2 variant (p.D314E) was observed in 2 patients with sALS and 5 of 727 controls indicating that this variant might be a rare polymorphism rather than a disease-causing mutation. A novel SIGMAR1 gene variant in the 3′-untranslated region (c.*58T>C) was found in 1 sALS and was absent in 727 control samples. Taken together, our data suggest that causative mutations in the UBQLN2 and SIGMAR1 genes are rare in Korean patients with either familial or sporadic ALS.     

Mutational analysis of GIGYF2, ATP13A2 and GBA genes in Brazilian patients with early-onset Parkinson's disease

In the last decade, several genes have been linked to Parkinson's disease (PD), including GIGYF2, ATP13A2 and GBA. To explore whether mutations in these genes contribute to development of PD in the Brazilian population, we screened 110 patients with early-onset PD. No clearly pathogenic mutations were identified in ATP13A2 and GIGYF2. In contrast, we identified a significantly higher frequency of known pathogenic mutations in GBA gene among the PD cases (6/110 = 5.4%) when compared to the control group (0/155) (P = 0.0047). Our results strongly support an association between GBA gene mutations and an increased risk of PD. Mutations in GIGYF2 and ATP13A2 do not seem to represent a risk factor to the development of PD in the Brazilian population. Considering the scarcity of studies on GIGYF2, ATP13A2 and GBA mutation frequency in Latin American countries, we present significant data about the contribution of these genes to PD susceptibility.     

Mutation analysis of parkin and PINK1 genes in early-onset Parkinson's disease in China

A series of 69 Han Chinese PD patients (including 66 index cases and 3 relatives) with early-onset Parkinson's disease (EOPD) were studied to assess the frequency of parkin and PINK1 gene mutations. Mutation analysis of the parkin gene was performed by real-time quantitative polymerase chain reaction (QPCR), denaturing high-performance liquid chromatography (DHPLC) and DNA sequencing. For the PINK1 gene, DHPLC and DNA sequencing were used. Nineteen patients (including one relative) had mutation in the parkin gene, and the c.2T > C (p.M1T) was not reported previously. No mutation of the PINK1 gene was found. The onset age of the patients with mutations in the parkin was earlier than that of those without mutation (p < 0.05). We concluded that mutations in parkin gene are common in Chinese EOPD patients, and mainly are exon rearrangements, while mutation in PINK1 might be not common in Chinese EOPD patients.     

The localization of proteins encoded by CRYM, KIAA1199, UBA52, COL9A3, and COL9A1, genes highly expressed in the cochlea

Genes that are highly expressed in the inner ear, as revealed by cDNA microarray analysis, may have a crucial functional role there. Those that are expressed specifically in auditory tissues are likely to be good candidates to screen for genetic alterations in patients with deafness, and several genes have been successfully identified as responsible for hereditary hearing loss. To understand the detailed mechanisms of the hearing loss caused by the mutations in these genes, the present study examined the immunocytochemical localization of the proteins encoded by Crym, KIAA1199 homolog, Uba52, Col9a3, and Col9a1 in the cochlea of rats and mice. Confocal microscopic immunocytochemistry was performed on cryostat sections. Ultrastructurally, postembedding immunogold cytochemistry was applied using Lowicryl sections. Crym protein was predominantly distributed in the fibrocytes in the spiral ligament, as well as the stria vascularis in rats. KIAA1199 protein homolog was localized in various supporting cells, including inner phalangeal, border, inner and outer pillar, and Deiters' cells. Uba52 protein was restrictedly localized within the surface of the marginal cells of the stria vascularis. Collagen type IX was found within the tectorial membrane as well as fibrocytes in the spiral ligament. The present results showed cell-specific localization of the encoded proteins of these highly expressed genes, indicating that the coordinated actions of various molecules distributed in different parts of the cochlea are essential for maintenance of auditory processing in the cochlea.     

Unilateral gonadal dysgenesis with both testis and fallopian tube on the same side in a 45,X/46,X INV (Y) mosaic male

A 5-year-old male with ambiguous external genitalia, hypospadias and microphallus without an urethral orifice was referred for cytogenetic studies. Exploratory laparotomy revealed presence of an infantile uterus and unilateral gonadal dysgenesis with both testes and fallopian tube on the right side. The metaphase cells from peripheral blood culture showed both 45,X/46,X inverted Y (p11.2q11.23) cell-lines (982). The inverted Y was found to be of paternal origin. Maternal chromosomal pattern was normal 46,XX. The presence of a fallopian tube next to testis suggest absence of secretion of anti-Mullerian hormone by Sertoli cells. The absence of Wolffian duct derivatives suggest insufficient secretion of testosterone by Leydig cells.     

The C9ORF72 expansion does not affect the phenotype in Nasu-Hakola disease with the DAP12 mutation

Nasu-Hakola disease (NHD) is a rare autosomal recessive disease that is characterized by cyst-like bone lesions and pathologic fractures combined with an early-onset frontal type of dementia. Mutations in DNAX-activation protein 12 (DAP12) and triggering receptor expressed on myeloid cells 2 (TREM2) are the known genetic causes of NHD. However, the role of both these genes in the neurodegenerative process is still partly unclear, and the input of other modifying factors has been postulated. Frontotemporal lobar degeneration (FTLD) is a neuropathologically and genetically heterogeneous neurodegenerative disease. A hexanucleotide repeat expansion in the chromosome 9–associated open reading frame 72 (C9ORF72) gene is the most common cause of familial FTLD in Finland. Here, we describe a family with 3 siblings with a clinical diagnosis of NHD. All patients had an equivalent age of onset of the behavioral/cognitive symptoms, and brain imaging revealed a similar pattern of brain atrophy and calcification in putamen and caudate nucleus. Case II-3 had the most severe phenotype with epilepsy and a rapid cognitive decline. Genetic analyses were performed in 2 patients (cases II-2 and II-3), and both had a homozygous DAP12 deletion. Because the role of DAP12 and TREM2 in neurodegeneration in NHD is partly unclear, our aim was to evaluate the role of other genetic variations as modifiers. The C9ORF72 expansion was found in case II-2. Exome sequencing did not reveal any other mutations that could be involved in FTLD. Case II-3 had a novel predictably deleterious mutation in the progressive myoclonic epilepsy type 2 (EPM2), which may have influenced his epilepsy as the EPM2 has been implicated in Lafora progressive myoclonic epilepsy. We conclude that the C9ORF72 expansion is probably an incidental finding because it did not have any apparent influence on the phenotype. Exome sequencing identified several rare missense variants and indels. Additional analyses in other NHD patients will be needed to elucidate their clinical relevance.