Female pseudohermaphroditism caused by a novel homozygous missense mutation of the GR gene

Familial glucocorticoid resistance is characterized by increased cortisol secretion without clinical evidence of hypercortisolism, but with manifestations of androgen and mineralocorticoid excess. This condition is mainly caused by mutations of the GR gene that cause inadequate transduction of the glucocorticoid signal in glucocorticoid target tissues. The clinical features of glucocorticoid resistance in females include hirsutism, acne, male pattern baldness, oligomenorrhea, and oligoanovulation. We describe here a new phenotype, female pseudohermaphroditism and severe hypokalemia, caused by a homozygous inactivating mutation of the GR gene. The proband was born with ambiguous genitalia from consanguineous parents and was mistreated as a 21-hydroxylase deficiency case since the age of 5 yr. She had very high levels of plasma ACTH (759 pg/ml or 167 pmol/liter) and high levels of cortisol (28-54 microg/dl or 772-1490 nmol/liter), androstenedione (5-14 ng/ml or 17-48 nmol/liter), T (174-235 ng/dl or 7-8 nmol/liter), and 17-hydroxyprogesterone (8-12 ng/ml or 24-36 nmol/liter). Her cortisol and 17-hydroxyprogesterone levels were not compatible with the diagnosis of classic congenital adrenal hyperplasia; furthermore, cortisol was not properly suppressed after dexamethasone administration (28 microg/d or 772 nmol/liter). Her laboratory evaluation indicated a diagnosis of glucocorticoid resistance. To investigate this puzzling clinical and biochemical picture, we analyzed both GR and CYP21 genes. Indeed, a homozygous T to C substitution at nucleotide 1844 in exon 5 of the GR gene was identified in the patient that caused a valine to alanine substitution at amino acid 571 in the ligand domain of the receptor. Her parents and an older sister were heterozygous for this mutation. A whole Epstein-Barr virus-transformed cell dexamethasone-binding assay revealed that this Ala(571) mutant had a 6-fold reduction in binding affinity compared with the wild-type receptor. In a functional assay using mouse mammary tumor virus promoter-driven luciferase reporter gene, the mutant receptor displayed 10- to 50-fold less trans-activation activity than the wild-type receptor. In addition, a large heterozygous CYP21 conversion was identified in the patient and her father. In conclusion, we described the first case of female pseudohermaphroditism caused by a novel homozygous GR gene mutation. This phenotype indicates that pre- and postnatal virilization can occur in females with the glucocorticoid resistance syndrome.     

FH-Freiburg: a novel missense mutation (C317Y) in growth factor repeat A of the low density lipoprotein receptor gene in a German patient with homozygous familial hypercholesterolemia

We describe the characterization of a novel mutation in the low density lipoprotein receptor (LDL-R) gene in a patient with true homozygous familial hypercholesterolemia (FH). The combined use of denaturing gradient gel electrophoresis (DGGE) and sequencing of genomic DNA revealed a guanine to adenine base substitution at nucleotide position 1013 of the LDL-R cDNA. This point mutation results in a change from cysteine to tyrosine at amino acid residue 317 of repeat A of the epidermal growth factor (EGF) precursor homology domain. Binding, uptake and degradation of iodinated LDL in skin fibroblasts from the homozygous patient were less than 10% of normal. In contrast, binding, uptake and degradation of iodinated VLDL was reduced by only 60, 30, and 38%, respectively. Incubation of the patient's fibroblasts in the presence of cholesterol diminished the residual binding of VLDL by 50%, suggesting that the loss of the highly conserved cysteine at position 317 results in a LDL-R that fails to bind LDL, but retains some ability to bind VLDL by interacting with the apolipoprotein E. Both parents were heterozygous for the C317Y mutation. Interestingly, however, the father presented with markedly elevated levels of triglycerides and VLDL cholesterol, whereas his LDL cholesterol was unexpectedly low. The mother of the index patient had only slightly elevated LDL cholesterol. These observations testify to the biological complexity of genotype-environment interactions in individuals carrying mutations at the LDL-R locus and indicate that genetic analysis importantly complements the clinical and biochemical diagnosis of patients with hyperlipidemia.     

A novel intronic homozygous mutation in the AMT gene of a patient with nonketotic hyperglycinemia and hyperammonemia

Metabolic Brain Disease - Nonketotic Hyperglycinemia is an autosomal recessive disorder characterized by defects in the mitochondrial glycine cleavage system. Most patients present soon after birth...     

A novel missense mutation in the human plasmin inhibitor (alpha2-antiplasmin) gene associated with a bleeding tendency

Heterozygosity for a G --> A mutation converting Val384(GTG) to Met(ATG) associated with plasmin inhibitor (alpha2-antiplasmin) deficiency was identified in three family members with bleeding tendency. The proband had traumatic breast haematoma and per-/postoperative bleeds. An affected daughter required a blood transfusion after a normal delivery and a son had prolonged bleeding after tooth extraction. The plasma plasmin inhibitor activities of the affected family members were reduced to 49-66% of normal. The antigenic concentrations determined by electroimmunoassay were reduced to 57-68% of normal. Crossed immunoelectrophoresis of plasma from the proband showed a normal pattern. The amino acid Val384 is located eight residues C-terminal (P8') of the P1 residue (Arg376) in the reactive site. The P8' residues of bovine and mouse plasmin inhibitor are both Val. Among other serpins the P8' residue is unconserved. The mutation was not present in the non-affected family member or 30 blood donors. In addition to the Val384Met mutation two new polymorphisms Ala-26(GCG)/Val(GTG) and Arg407(AGG)/Lys(AAG) and one previously reported polymorphism Arg6(CGG)/Trp(TGG) were identified in the plasmin inhibitor gene of the family. The allelic frequencies among 30 blood donors with normal values of plasma plasmin inhibitor (functional) were 0.84/0.16 for C/T in codon -26, 0.81/0.19 for C/T in codon 6 and 0.83/0.17 for G/A in codon 407.     

1例先天性脊柱骨骺发育不良患者COL2A1基因新突变

目的检测1例先天性脊柱骨骺发育不良(SEDC)患者基因的突变情况。方法根据临床表现和骨骼影像学诊断先证者为SEDC。收集患者血液标本,提取基因组DNA,采用PCR扩增COL2A1外显子,对所有外显子进行测序分析。结果患者短颈,椎体扁平,股骨颈结构不规则,髋臼顶扁平,脊柱侧弯。基因检测表明COL2A1基因42号外显子2735位核苷酸发生一个新的错义突变,由G变成A(c.2735GA),使912号氨基酸由甘氨酸变成了天门冬氨酸(p.G912D)。结论在1例中国SEDC患者中发现了一个COL2A1基因新的错义突变p.G912D。     

A homozygous kinase-defective mutation in the insulin receptor gene in a patient with leprechaunism

Summary We report a homozygous missense mutation at position 1092 (substitution of glutamine for arginine) in the tyrosine kinase domain of the insulin receptor in a patient with leprechaunism associated with severe insulin resistance and intrauterine growth retardation. Site-directed mutagenesis as well as analyses of the patient's lymphocytes revealed that this mutation causes a marked decrease in tyrosine kinase activity of the insulin receptor without any defect in insulin binding, which causes severe defects in insulin-stimulated glucose transport, glycogen synthesis and DNA synthesis. Thus, this is the first homozygous mutation resulting in a selective-kinase defect of the insulin receptor. Interestingly, the parents who are cousins and are heterozygous for the mutation have type A insulin resistance syndrome. This correlation between genotype and phenotype in a single pedigree suggests that the severity of the mutation will determine the phenotype. Based upon this assumption, we have been successful in prenatal diagnosis of the fifth child. Furthermore, we have demonstrated the effectiveness of clinical administration of insulin-like growth factor-I (IGF-I) in this patient and in vitro analysis of the patient's skin fibroblasts, suggesting that IGF-I can compensate for insulin action via the IGF-I receptor in a patient almost lacking functional insulin receptors. [Diabetologia (1997) 40: 412–420] Received: 25 September 1996 and in revised form: 10 December 1996     

A novel missense mutation in the PHOX2B gene is associated with late onset central hypoventilation syndrome

We report the case of a 15-month-old male suffering from Late Onset Congenital Central Hypoventilation Syndrome and recto-sigmoid Hirschsprung's disease, an association that has not been reported thus far. Nevertheless, our patient showed a missense mutation of the PHOX2B gene already known in isolated late onset central hypoventilation, resulting in a substitution of the Ala140 residue with a Glu residue (p.A140E). The present association of LO-CHS and HSCR in a patient harboring a rare and atypical PHOX2B mutation allows to refine the mutational spectrum of this disease and suggests individualized ventilatory care along with specific surgical and oncological approaches.     

A novel missense mutation of the MEN1 gene in a multiple endocrine neoplasia type 1 patient associated with carcinoid syndrome

We report a multiple endocrine neoplasia type 1 (MEN1) patient associated with carcinoid syndrome. A 50-year-old woman had parathyroid hyperplasia with primary hyperparathyroidism, a pancreatic tumor and carcinoid tumors in the liver and duodenum. The primary lesion of the carcinoid was probably the bronchus. Direct sequencing analysis revealed a novel missense mutation at codon 342 in exon 7 causing an amino acid change from alanine to proline (A342P) of the MEN1 gene. Loss of heterozygosity (LOH) was also detected in the resected parathyroid tissue. This mutation appeared to play an important role in the tumorigenesis of the endocrine tissues in the present case.     

Congenital generalized lipodystrophy in an Indian patient with a novel mutation in BSCL2 gene

Congenital generalized lipodystrophy (CGL) is an autosomal recessive metabolic syndrome with involvement of multiple organs. Mutations in BSCL2 are known to be associated with a severe form of CGL and mental retardation (MR). The genetic heterogeneity in CGL patients is accompanied by phenotypic heterogeneity in different ethnic groups. Studies in the Indian context are very few in this regard. We report here a detailed clinical analysis of a CGL case from infancy to adult hood. Interestingly, the patient was found to be homozygous for a novel BSCL2 mutation, but with normal intellectual development contrasting with the MR associated with BSCL2 mutation in CGL patients. The biochemical investigations at the time of diagnosis (9 months) included total cholesterol, total lipids, triglycerides, phospholipids, β-lipoprotein and free fatty acids, which were above normal limits. The clinical phenotype, viz. lack of subcutaneous fat, hepatosplenomegaly, cardiomegaly, and advanced bone age was also documented. The patient was found to be insulin resistant and diabetes mellitus was diagnosed by age 13 years. Ultrasonography of the ovaries at age 22 showed polycystic features with elevated levels of gonadotropins and negligible levels of serum leptin. For genetic analysis, direct DNA sequencing of BSCL2 was carried out and disclosed an 11-base-pair deletion in exon 6 (H217fsX272) resulting in a truncated protein. This is a novel mutation that contributes to CGL formation in a family of Indian origin and adds to the array of variants reported in this disorder. Moreover, the novel mutation is found to be associated with normal intellectual ability.     

Identification of a truncated dual oxidase 2 (DUOX2) messenger ribonucleic acid (mRNA) in two rat thyroid cell lines. Insulin and forskolin regulation of DUOX2 mRNA levels in FRTL-5 cells and porcine thyrocytes

The Duox2 flavoprotein is strongly expressed in the thyroid gland, where it plays a critical role in the synthesis of thyroid hormones likely by providing thyroperoxidase with H(2)O(2). A truncated DUOX2 mRNA was isolated from the rat thyroid cell line FRTL-5. The cDNA sequence predicted an open reading frame of 1458 bp, encoding a polypeptide of 486 amino acids corresponding to the carboxyl fragment of the Duox2 flavoprotein. The truncated form of DUOX2 mRNA, expressed in another rat thyroid cell line, the PC Cl3 cell line, was absent from Fischer rat thyroid glands. Although it was expressed in both cell lines to a greater extent than normal mRNA, it failed to support protein synthesis in an in vitro translation system. Insulin increased the levels of both normal and truncated DUOX2 mRNA in FRTL-5 cells grown in TSH-free medium containing a low concentration of serum. The stimulating effect of insulin on DUOX2 mRNA expression was reproduced in pig thyroid follicles in primary culture. The presence of insulin in the culture medium converted forskolin from a stimulator to an inhibitor in FRTL-5 cells maintained in low serum conditions, but not in porcine thyrocytes in primary culture.