Anti-Müllerian hormone Bruxelles: a nonsense mutation associated with the persistent Müllerian duct syndrome.

The persistent Müllerian duct syndrome (PMDS) is characterized by the persistence of Müllerian derivatives, uterus and tubes, in otherwise normally virilized males. In a previous study, we showed that this syndrome is heterogeneous, with lack of production of anti-Müllerian hormone (AMH) by testicular tissue accounting for only some, AMH-negative, cases of this disorder. We have characterized the point mutation responsible for an AMH-negative PMDS in three siblings: a guanine to thymine transversion at position 2096 in the fifth exon changes a GAA triplet, coding for glutamic acid, to a TAA stop codon. The mutation could also be recognized, using the polymerase chain reaction, on RNA produced in trace amounts by a lymphoblastic cell line. The translation product, although undetectable in testicular tissue, could be visualized in culture medium of cells transfected with the mutant gene.     

Anorchia and persistent Müllerian duct: a variant of the embryonic testicular regression syndrome.

A 20-yr-old phenotypical male with a 46, XY chromosome complement, a hernia uteri inguinale, and bilateral anorchia was studied. Eunochoidal body proportions, infantile type of male external genitalia with empty scrotum, underdeveloped sexual characteristics, and delayed bone age suggested the existence of inadequate testicular function. Extremely low levels of circulating testosterone and a lack of response to hCG stimulation was found. Persistently elevated blood levels of LH and FSH with an adequate pituitary response to an iv bolus of synthetic LRH was demonstrated, thus indicating inadequate endocrine gonadal function as well as functional integrity of the hypothalamic-pituitary unit. At the time of an inguinal hernioplasty, a small but well developed uterus was removed. No gonads were found within the true pelvis, inguinal canals, or along the anatomical pathways of testicular descent. A cord-like structure found in the left inguinal canal contained only fibrous tissue without gonadal elements. It is proposed that the occurrence of two altered events during embryogenesis, failure of Müllerian duct regression and late testicular regression, may explain the underlying defect in this unusual abnormality of sexual differentiation.     

Clinical and molecular genetics of the short QT syndrome

PURPOSE OF REVIEW: Sudden cardiac death in patients without structural heart disease remains a challenge in diagnostics and risk stratification. Genetically determined arrhythmias are a potential cause for a primary electrical disease. A recently discovered primary electrical disease is discussed. RECENT FINDINGS: The inherited short QT syndrome is a recently recognized genetic condition, which is associated with atrial fibrillation, syncope and/or sudden cardiac death. Attention has been focused on diagnostic ECG features, the identification of underlying mutations and mechanisms of arrhythmogenesis. SUMMARY: The short QT syndrome is clinically associated with atrial fibrillation, syncope and sudden cardiac death. A shortened QT interval (QTc <360 ms) and reduced ventricular refractory period together with an increased dispersion of repolarization constitute the potential substrate for reentry and life-threatening ventricular tachyarrhythmia. To date, gain-of-function mutations in KCNH2, KCNQ1, KCNJ2, encoding potassium channels and loss-of-function mutations in CACNA1C and CACNB2b, encoding L-type calcium channel subunits have been identified. The therapy of choice is the implantable cardioverter defibrillator in symptomatic patients. Quinidine has been shown to prolong the QT interval and to normalize the effective refractory periods of the atrium and ventricle in patients with short QT-1 syndrome.     

Clinical aspects and molecular genetics of the Jervell- and Lange-Nielsen Syndrome

In contrast to the Romano-Ward (R-W) syndrome, the Jervell and Lange-Nielsen (J-LN) syndrome is an autosomal recessive inherited disease characterized by QT-prolongation in the electrocardiogram (ECG) and recurrent syncopal attacks which are also typical for the R-W syndrome, but also by congenital deafness. Recently, defect alleles in the genes for KCNQ1 and KCNE1 have been identified in patients with the J-LN syndrome. These genes may be causative for the R-W syndrome as well but in J-LN patients, they are only present in the homozygote or compound heterozygote form. In the present paper, we review the clinical and genetic similarities and differences of the J-LN and the R-W syndrome as well as the diagnostic and therapeutic management of these patients and their family members.     

Clinical genetics of Kallmann syndrome

The Kallmann syndrome (KS) combines hypogonadotropic hypogonadism (HH) with anosmia. This is a clinically and genetically heterogeneous disease. KAL1, encoding the extracellular glycoprotein anosmin-1, is responsible for the X chromosome-linked recessive form of the disease (KAL1). Mutations in FGFR1 or FGF8, encoding fibroblast growth factor receptor-1 and fibroblast growth factor-8, respectively, underlie an autosomal dominant form with incomplete penetrance (KAL2). Mutations in PROKR2 and PROK2, encoding prokineticin receptor-2 and prokineticin-2, have been found in heterozygous, homozygous, and compound heterozygous states. These two genes are likely to be involved both in autosomal recessive monogenic (KAL3) and digenic/oligogenic KS transmission modes. Mutations in any of the above-mentioned KS genes have been found in less than 30% of the KS patients, which indicates that other genes involved in the disease remain to be discovered. Notably, KS may also be part of pleiotropic developmental diseases including CHARGE syndrome; this disease results in most cases from neomutations in CHD7 that encodes a chromodomain helicase DNA-binding protein.     

Cellular and molecular aspects of Goodpasture syndrome

Goodpasture syndrome, a rare human autoimmune disorder, is characterized by the presence of pathogenic autoantibodies that react with the components of the glomerular basement membrane. The clinical condition of the Goodpasture syndrome is characterized by an acute necrotizing glomerulonephritis, often with accompanying pulmonary hemorrhage. Notably, the Goodpasture antigen has been localized to the noncollagenous domain of the alpha3 chain of type IV collagen. Additionally, human leukocyte antigen-DR2, and to a lesser extent human leukocyte antigen-DR4, have been identified as important restriction elements. The role of T cells in Goodpasture syndrome is indicated by the highly restricted specificity of the antibody response and the strong major histocompatibility complex class II association. In this review article, we briefly describe the latest views on the molecular and cellular themes of Goodpasture syndrome.     

成骨不全的临床表现与分子遗传学

成骨不全是一组单基因突变引起的骨脆性增加的遗传性骨病,主要特征为反复骨折和骨畸形。该病有多种致病基因且表型庞杂。本文就成骨不全的临床表现及遗传学进展进行综述,试图归纳出表型与致病基因间的关系。     

Gitelman综合征分子遗传学研究进展

Gitelman综合征是由位于染色体16q13的SLC12A3基因突变引起的常染色体隐性遗传病,患病率为1~10∶40000,SLC12A3基因编码噻嗪类敏感的钠氯共同转运体(sodium-chloride cotransporters,NCC),介导Na+和Cl-的重吸收。该综合征以低钾性碱中毒、低镁血症和低尿钙为特征,基因型与表型之间有一定的相关性。在之前的研究中,已经发现了超过500种基因突变,并对其中的一些突变进行了功能学分析。本文综述了Gitelman综合征相关的基因突变和功能学研究,对其基因型和表型的关系进行了分析,总结了Gitelman综合征的分子遗传学研究进展。     

Current developments in the molecular genetics of the polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) is most likely a complex trait with an oligogenic basis. In this article, we present evidence from molecular genetic studies for involvement of the steroid synthesis gene CYP11a (coding for P450 cholesterol side-chain cleavage) in the aetiology of hyperandrogenism. Variation in the regulatory region of the insulin gene also appears to contribute to the development of PCOS.     

Clinical and molecular genetics of primary pigmented nodular adrenocortical disease

Carney complex (CNC) is a multiple endocrine neoplasia (MEN) syndrome associated with other, non-endocrine manifestations such as lentigines, cardiac myxomas and schwannomas. Primary pigmented nodular adrenocortical disease (PPNAD), leading to corticotrophin-independent Cushing's syndrome is the most frequent endocrine lesion in CNC. The complex has been mapped to 2p16 and 17q22-24, although additional heterogeneity may exist. The gene coding for the protein kinase A (PKA) type I-a regulatory subunit (RIa), PRKAR1A, had been mapped to 17q. Cloning of the PRKAR1A genomic structure and its sequencing showed mutations in CNC-, CNC with PPNAD- and sporadic PPNAD-patients. In CNC tumors, PKA activity showed increased stimulation by cAMP, whereas PKA activity ratio was decreased, and in CNC tumors, there is LOH of the normal allele, suggesting that normal PRKAR1A may be a tumor suppressor in these tissues. CNC is the first human disease caused by mutations of one of the subunits of the PKA enzyme, a critical component of the cAMP signaling system and a potential participant in many other signaling pathways.