Nine novel mutations in NR0B1 (DAX1) causing adrenal hypoplasia congenita

X‐linked adrenal hypoplasia congenita (AHC) is caused by mutations in the NR0B1 gene. This gene encodes an orphan member of the nuclear receptor superfamily, DAX1. Ongoing efforts in our laboratory have identified nine novel NR0B1 mutations in X‐linked AHC patients (Y81X, 343delG, 457delT, 629delG, L295P, 926‐927delTG, 1130delA, 1141‐1155del15, and E428X). Two additional families segregate previously identified NR0B1 mutations (501delA and R425T). Sequence analysis of the mitochondrial D‐loop indicates that the 501delA family is unrelated through matrilineal descent to our previously analyzed 501delA family. © 2001 Wiley‐Liss, Inc.     

Novel missense mutation (Leu466Arg) of the DAX1 gene in a patient with X-linked congenital adrenal hypoplasia

We identified a DAX1 missense mutation, a substitution of arginine for leucine at codon 466 (Leu466Arg), in an infant with X-linked congenital adrenal hypoplasia (AHC). A heterozygous substitution, Leu466Arg, was also identified in his mother and sister. Since leucine at position 466 is well conserved among other orphan nuclear hormone receptor superfamilies and Leu466Arg was not detected among 50 normal Japanese control individuals, the mutation is most likely responsible for X-linked AHC. It is interesting to note that Leu466Arg among all mutations ever reported is located at the most C-terminal region of the DAX-1 protein. Most mutations identified previously were located in the C-terminal presumptive ligand binding domain. Hence, the C-terminal end of the DAX-1 protein may play an important role in the biological function, such as in normal adrenal embryogenesis. Am. J. Med. Genet. 84:87–89, 1999. © 1999 Wiley-Liss, Inc.     

Molecular Xp deletion in a male: suggestion of a locus for hypogonadotropic hypogonadism distal to the glycerol kinase and adrenal hypoplasia loci

We have analyzed one patient with a syndrome of glycerol kinase deficiency (GKD), adrenal hypoplasia (AH), mental retardation (MR) and hypogonadotropic hypogonadism (HH). Although a cytogenetic analysis of the patient failed to reveal any detectable chromosomal abnormality, Southern blot analysis, using DNA probes from the Xp21-Xp22 region, revealed a molecular deletion localized between the DXS41 and the DXS268 loci. Our results together with those of others (van Ommen et al. 1986, 1987, Francke et al. 1987, Yates et al. 1987, Chelly et al. 1988) suggest that the GK gene is located between the DXS68 and DXS268 loci. In addition, we propose a locus for HH in Xp, distal to the genes for GK and AH.     

A novel stop-loss DAX1 variant affecting its protein-interaction with SF1 precedes the adrenal hypoplasia congenital with rare spontaneous precocious puberty and elevated hypothalamic-pituitary-gonadal/adrenal axis responses

The case study unveils the likely mechanism of a novel stop-loss DAX1 variant preceding the prolonged precocious puberty in the adrenal hypoplasia congenital (AHC) boy.A boy aged five years and nine months initially examined for the primary adrenal insufficiency symptoms. Next-generation sequencing confirmed the X-linked inheritance of a novel stop-loss DAX1 variant: c.1411T>C/p.Ter471Gln associated with AHC in the patient. The patient was subjected to a brief clinical follow-up from 11 to 15.1 years of age. The effect of the mutant-DAX1 variant (p.Ter471Gln) on DAX1-steroidogenic factor 1 (SF1) (protein-protein) interaction was studied by protein-protein docking using the ClusPro-online tool.At 5.9 yrs of age, the patient exhibited precocious puberty with the secondary sexual characteristics of Tanner 2 stage (of 9–14 yrs of age). The patient showed primary adrenal insufficiency with diminished cortisol concentrations at blood serum (25 ng/ml) and urine (3.55 μg/24 h) levels. Upon steroidal exposure, the patient showed normalized serum cortisol levels of 45–61 ng/ml. However, the precocious puberty got prolonged with the increased penis length of 8.5 cm and the bone age of 18 yrs old during the follow-up. The patient showed increased basal serum adrenocorticotropic hormone (110->2000 pg/ml) and follicle-stimulating hormone (18.4–22.3 mIU/ml) concentrations. Following an elevated hypothalamic-pituitary-gonadal axis activity witnessed upon gonarellin stimulation. Protein-protein docking confirmed a weaker interaction between the mutant-DAX1 (p.Ter471Gln) protein and the wild-SF1 protein.Overall, we hypothesize the weakened mutant-DAX1-SF1 (protein-protein) interaction could govern the prolonged precocious puberty augmented with the elevated hypothalamic-pituitary-gonadal/adrenal axis responses via SF1-induced neuronal nitric oxide synthetase activation in the patient.     

Novel missense mutation (Leu466Arg) of the DAX1 gene in a patient with X-linked congenital adrenal hypoplasia.

We identified a DAX1 missense mutation, a substitution of arginine for leucine at codon 466 (Leu466Arg), in an infant with X-linked congenital adrenal hypoplasia (AHC). A heterozygous substitution, Leu466Arg, was also identified in his mother and sister. Since leucine at position 466 is well conserved among other orphan nuclear hormone receptor superfamilies and Leu466Arg was not detected among 50 normal Japanese control individuals, the mutation is most likely responsible for X-linked AHC. It is interesting to note that Leu466Arg among all mutations ever reported is located at the most C-terminal region of the DAX-1 protein. Most mutations identified previously were located in the C-terminal presumptive ligand binding domain. Hence, the C-terminal end of the DAX-1 protein may play an important role in the biological function, such as in normal adrenal embryogenesis.     

一种DAX-1基因移码突变(428delG)引起的X-连锁先天性肾上腺发育不良

目的 研究1个X-连锁先天性肾上腺发育不良家系的临床特征,检测患者及其家属中是否存在相关DAx-1基因的突变.方法 收集1个临床诊断X-连锁先天性肾上腺发育不良的家系中2例患者及亲属的临床资料和外周血标本;提取基因组DNA,设计4对引物扩增DAX-1基因的2个外显子,PCR扩增DAX-1的全部外显子,扩增产物经纯化后进行直接测序.测序结果 在核苷酸序列数据库进行比较分析.结果 两例患者(表兄弟)DAX-1基因第1外显子处均存在428delG半合子移码突变.而患者的基因型与其临床表型并不一致.家系中有3例女性(他们的母亲及外祖母)为此突变的杂合子,正常人及家族中其他成员无该位点突变.结论 在1个中国人先天性肾上腺发育不良家系中发现DAX-1新的移码突变428delG.各种基因型与表现型之间并无相关性.     

Genetics of congenital hypogonadotropic hypogonadism in Denmark

Congenital hypogonadotropic hypogonadism (CHH) is a rare disorder characterized by incomplete/absent puberty caused by deficiency or defective action of gonadotropin-releasing hormone (GnRH). The phenotypic features of patients with CHH vary from genital hypoplasia and absent puberty to reversal of HH later in life. We examined the genetics and clinical features of CHH in Denmark. Forty-one male patients were screened for mutations in KAL1, FGFR1, FGF8, PROK2, PROKR2, GNRHR, TAC3, TACR3, and KISS1R. CHD7 was screened in two patients with hearing loss. In 12 patients, a molecular genetic cause for CHH was found. Four patients had mutations in KAL1 (C105VfsX13, C53X, ex5-8del, R257X), and five in FGFR1 (G97S, R209C, A512V, R646W, and c.1614C>T, (p.I538I), predicted to affect splicing). All 9 had severe HH (cryptorchidism and/or micropenis), and 2 had cleft lip/palate. One patient with a previously reported homozygous R262Q mutation in GNRHR displayed fascinating temporal variation in his phenotype. Two patients with hearing loss had CHD7 mutations (c.7832_7841del (p.K2611MfsX25) and c.2443-2A>C), confirming that CHH patients with CHARGE syndrome-associated features should be screened for mutations in CHD7.     

Isolated hypogonadotropic hypogonadism with SOX2 mutation and anophthalmia/microphthalmia in offspring

Isolated hypogonadotropic hypogonadism (IHH) is a genetically heterogeneous condition in which patients frequently require assisted reproduction to achieve fertility. In patients with IHH who are otherwise well, no particular increased risk of congenital anomalies in the resultant offspring has been highlighted. Heterozygous mutations in SOX2 are the commonest single-gene cause of anophthalmia/microphthalmia (A/M) and sometimes result in pituitary abnormalities. We report a family with a novel frameshift mutation in the SOX2 transactivation domain, p.Gly280AlafsX91, resulting in bilateral anophthalmia and subtle endocrinological abnormalities in a male sibling, and unilateral microphthalmia in a female sibling. The mutation is present in their mother who has IHH, but has no eye disorders or other anomalies. She underwent assisted reproduction to achieve fertility. This report has important implications for the evaluation of patients with IHH, particularly in the setting of planned infertility treatment.     

Prevalence and associated phenotypes of PLXNA1 variants in normosmic and anosmic idiopathic hypogonadotropic hypogonadism

Idiopathic hypogonadotropic hypogonadism (IHH) can be divided into two major forms, normosmic IHH and Kallmann syndrome (KS). Genetic mutations are responsible for the majority of IHH. PLXNA1 has recently been implicated in the GnRH neuron migration and the etiology of KS. We aimed to investigate the prevalence and associated phenotypes of PLXNA1 variants in a large cohort of IHH patients. We screened the whole exome data of 215 IHH patients in a single center for causative PLXNA1 variants. Our studies showed eight novel (p.Arg836His, p.Lys1451Arg, p.Val287Met, p.Val536Ile, p.Ser1850Arg, p.Ile1701Val, p.Arg319Trp, and p.Pro485Leu) and two previously described (p.Arg528Trp and p.Gly720Glu) heterozygous PLXNA1 variants in nine affected individuals from seven unrelated families. Only three of nine patients were anosmic (KS) while the remaining patients showed normal olfactory function (nIHH). Seven of nine patients (77.7%) harbored additional one or two variants in other nIHH/KS-associated genes, including PROKR2, IGSF10, HS6ST1, SEMA3E, CCDC141, FGFR1, NRP1, POLR3A, and SRA1. Our findings indicate that PLXNA1 variants cause not only anosmic but also normosmic IHH with a relatively high prevalence (3.9%). Heterozygous missense PLXNA1 variants appear to be involved together with other IHH gene variants in bringing about the IHH disease phenotype.     

Genetic testing facilitates prepubertal diagnosis of congenital hypogonadotropic hypogonadism

Neonatal micropenis and cryptorchidism raise the suspicion of congenital hypogonadotropic hypogonadism (CHH), a rare genetic disorder caused by gonadotropin‐releasing hormone deficiency. Low plasma testosterone levels and low gonadotropins during minipuberty provide a clinical diagnostic clue, yet these tests are seldomly performed in general practice. We report a male neonate with no family history of reproductive disorders who was born with micropenis and cryptorchidism. Hormonal testing at age 2.5 months showed low testosterone (0.3 nmol/L) and undetectable gonadotropins (luteinizing hormone and follicle‐stimulating hormone both <0.5 U/L), suggestive of CHH. Genetic testing identified a de novo, heterozygous mutation in fibroblast growth factor receptor 1 (FGFR1 p.L630P). L630 resides on the ATP binding cleft of the FGFR1 tyrosine kinase domain, and L630P is predicted to cause a complete loss of receptor function. Cell‐based assays confirmed that L630P abolishes FGF8 signaling activity. Identification of a loss‐of‐function de novo FGFR1 mutation in this patient confirms the diagnosis of CHH, allowing for a timely hormonal treatment to induce pubertal development. Therefore, genetic testing can complement clinical and hormonal assessment for a timely diagnosis of CHH in childhood.     

Functional analysis of SEMA3A variants identified in Chinese patients with isolated hypogonadotropic hypogonadism

Isolated hypogonadotropic hypogonadism (IHH) is a rare disorder characterized by impaired sexual development and infertility, caused by the deficiency of hypothalamic gonadotropin-releasing hormone neurons. IHH is named Kallmann's syndrome (KS) or normosmic IHH (nIHH) when associated with a defective or normal sense of smell. Variants in SEMA3A have been recently identified in patients with KS. In this study, we screened SEMA3A variants in a cohort of Chinese patients with IHH by whole exome sequencing. Three novel heterozygous SEMA3A variants (R197Q, R617Q and V458I) were identified in two nIHH and one KS patients, respectively. Functional studies indicated that R197Q and R617Q variants were ineffective in activating the phosphorylation of FAK (focal adhesion kinase) in GN11 cells, despite normal production and secretion in HEK293T cells. The V458I SEMA3A had defect in secretion as it was not detected in the conditioned medium from HEK293T cells. Compared with wild type SEMA3A protein, all three SEMA3A mutant proteins were ineffective in inducing the migration of GN11 cells. Our study further showed the contribution of SEMA3A loss-of-function variants to the pathogenesis of IHH.     

Adrenal hypoplasia congenita with multiple pituitary hormone deficiency without documented mutation in DAX1 or SF1 gene

A boy with adrenal hypoplasia congenita (AHC) and multiple pituitary hormone deficiency (MPHD), without mutations in the DAX1 or SF1 genes, is described. The association of AHC and MPHD has not been previously reported.     

A new family with chorioretinal dystrophy, spinocerebellar ataxia and hypogonadotropic hypogonadism (Boucher-Neuhäuser syndrome)

A family is described in which two brothers have spinocerebellar ataxia, hypogonadotropic hypogonadism and chorioretinal dystrophy. This report provides further evidence to support the previous suggestion that this triad of manifestations represents a specific single-gene disorder, designated Boucher-Neuhäuser syndrome. Analysis of affected individuals shows that neurological signs usually develop during adolescence or young adulthood (range: early childhood-fourth decade) and are slowly progressive or non-progressive, whereas ophthalmologic manifestations have an age of onset which varies from the first to the sixth decade of life and a pronounced variability in progression.     

局灶性真皮发育不全患者PORCN基因突变研究

目的 检测局灶性真皮发育不全(focal dermal hypoplasia,FDH)患者PORCN基因突变情况,探讨基因型与表型的相关性.方法 收集1例局灶性真皮发育不全患者及其家系3名正常成员及50名无血缘关系的健康对照者的外周血,采用PCR扩增PORCN基因所有外显子及其邻近的剪切位点进行直接测序.结果 患者PORCN基因核苷酸序列第2外显子上第149位碱基由G变为C,导致第38位氨基酸丙氨酸被脯氨酸代替(A38P),该患者家属及健康对照无此突变.患者临床表现中度.结论 该患者存在PORCN基因A38P突变,为一新的错义突变,可能是导致FDH发病机制之一.G149C基因型与中度的表型之间的关系与A38P错义突变对蛋白的影响有关,与以往结论不同.     

Thirteen novel mutations in the NR0B1 (DAX1) gene as cause of adrenal hypoplasia congenita

X-linked adrenal hypoplasia congenita (AHC) is a rare developmental disorder associated with primary adrenal insufficiency and combined primary and secondary male hypogonadism. It is caused by deletions or mutations of the NR0B1 (DAX1) gene encoding DAX1, an atypical orphan member of the nuclear receptor superfamily. The continuous molecular genetic analysis of male patients with primary adrenal insufficiency revealed 13 novel mutations within the coding region of the NR0B1 gene which are predicted to inactivate the DAX1 function. These were three nonsense mutations (c.312C>A, p.Cys104X, c.670C>T, p.Gln224X; and c.873G>A, p.Trp291X), five duplications (c.269_270dup, c.421_422dup, c.895_896dup, c.989dup, c.999_1000dup), and five deletions (c.483del, c.745_746del, c.734_740del, c.1092del, and c.1346del). All of the mutations resulted in a premature stop codon destroying the ligand binding domain of the predictive DAX1 protein.     

A de novo frameshift FGFR1 mutation extending the protein in an individual with multiple epiphyseal dysplasia and hypogonadotropic hypogonadism without anosmia

Multiple epiphyseal dysplasia (MED) is a genetically and clinically heterogeneous disease with both dominant and recessive inheritance. Eight different genes are known to cause the disease but in 15% of cases of MED, no mutation is found. Fibroblast growth factor receptor 1 (FGFR1) is a crucial regulator of bone formation and when mutated, can cause diseases with skeletal manifestations; nevertheless, MED has not been described in individuals with FGFR1 mutations. In this report, we describe a proband with MED and congenital normosmic hypogonadotropic hypogonadism (HH). DNA analysis showed a de novo frameshift variant in FGFR1 likely explaining the HH (p.Arg852Thrfs*165). No other mutation was found after a large gene sequencing panel, exome sequencing and an array CGH, except for a variant of unknown significance in FBN1 (rs755375255), but there were no features of a disease associated with FBN1 mutations and this variant is found a few times in population databases. We thus discuss the possibility that MED might be a new skeletal feature associated with FGFR1 mutations.