TBX5基因在中国人心手综合征患者中的突变分析

目的 检测中国心手综合征患者ＴＢＸ５基因突变。方法 利用单链构象多态性分析和测序方法,对７个心手综合征患者家系进行ＴＢＸ５基因突变检测。结果 发现３个家系患者有单链构象多态性改变,经测证实为３个新位点基因突变：１个心手综合征家系患者为ＴＢＸ５基因单个碱基缺失引起移码突变,２个心手综合征家系为ＴＢＸ５基因碱基替换引起错义突变。结论中国人ＴＢＸ５基因突变可引起心手综合征。     

TBX3 and TBX5 duplication: A family with an atypical overlapping Holt-Oram/ulnar-mammary syndrome phenotype

Holt-Oram syndrome (HOS) is a rare, autosomal dominant heart-hand syndrome caused by mutations in the TBX5 gene. A wide spectrum of TBX5 mutations have been reported previously, most resulting in a null allele leading to haploinsufficiency. TBX5 gene duplications have been previously reported in association with typical and atypical HOS phenotypes. Ulnar-Mammary syndrome (UMS) is a distinct rare, autosomal dominant condition caused by mutations in the TBX3 gene. TBX5 and TBX3 are physically linked in cis on human chromosome 12 and contiguous chromosome 12q24 deletions comprising both TBX5 and TBX3 genes have been previously reported but to our knowledge, duplications have never been described. We report on a large German family with at least 17 affected individuals over 6 generations bearing a duplication at 12q24.21 identified on array-CGH comprising both TBX5 and TBX3 genes. Affected patients are presenting with HOS and UMS symptoms, consisting of variable limb anomalies involving the radial and the ulnar rays and cardiac findings such as congenital heart defects, persistent arterial duct or aortic stenosis, and non-classical symptoms, such as supernumerary nipples and cardiomyopathy. Fluorescence in situ hybridisation confirmed a tandem duplication at the 12q24.21 locus. This is the first report of a contiguous TBX3/TBX5 duplication associated with HOS/UMS phenotype.     

Three novel TBX5 mutations in Chinese patients with Holt-Oram syndrome

Holt-Oram syndrome (HOS) is an autosomal dominant syndrome that comprises upper limb and cardiac defects. The gene responsible for HOS, TBX5, was isolated and many mutations have been identified in HOS patients. We analyzed 11 Chinese HOS patients (7 from three families and 4 sporadic cases) for TBX5 mutation by single strand conformation polymorphisms (SSCPs). Three SSCP changes were detected in two of the three familial cases and one sporadic case. Sequence analysis identified three novel, heterozygous mutations in TBX5: a frameshift mutation caused by one base deletion [C416del] in one family, a mis-sense mutation (Gln49Lys) induced by a base substitution (C145A) in another family, and the other mis-sense mutation (Ile54Thr) by T161C in one sporadic case. The patients with the frameshift mutations had severer clinical manifestations that involved aplasia/hypoplasia of the arm and thumbs, while those with the mis-sense mutations presented with milder anomalies such as absent or hypoplastic thumbs but without arm abnormalities. These observations may support a genotype-phenotype correlation in HOS patients with TBX5 mutation.     

Exclusion of linkage to 14q23-24 in a family with Holt-Oram syndrome

Holt-Oram syndrome is an autosomal dominant disorder with congenital heart defects and skeletal malformations of the upper extremities. A patient with a deletion of 14q23-24 and Holt-Oram syndrome has been described. In this report, however, genetic linkage to the 14q23-24 region is excluded in a multigeneration family with five available individuals affected with Holt-Oram syndrome. Familial Holt-Oram syndrome might be different from the syndrome with the 14q23-24 deletion.     

Linkage investigation of a large family with Reifenstein''s syndrome

Linkage analysis of a 116-member family with 11 males affected by Reifenstein's syndrome is reported. One X-chromosomal and eight autosomal markers were used. Close linkage can be excluded for P, K, MNS and Xg-a. A possibility of close linkage to ABO is discussed.     

Detection of the first gross CDC73 germline deletion in an HPT-JT syndrome family

Hereditary primary hyperparathyroidism (HPT) may develop as a solitary endocrinopathy (FIHP) or as part of multiple endocrine neoplasia Type 1, multiple endocrine neoplasia Type 2A, or hereditary HPT-jaw tumor syndrome. Inactivating germline mutations of the tumor suppressor gene CDC73 account for 14 and 50% of all FIHP and HPT-JT patients, respectively, and have also been found in almost 20% of apparently sporadic parathyroid carcinoma patients. Although more than 60 independent germline mutations have been described, to date no rearrangement affecting the CDC73 locus has been identified. By means of multiplex-PCR we found a large germline deletion affecting the whole gene in a two-generation HPT-JT family. Subsequently array-CGH and specific PCR analysis determined that the mutation spanned ～ 547 kb, and included four additional genes: TROVE2, GLRX2, B3GALT2, and UCHL5. Although no clear mutation-specific phenotype was found associated to the presence of the mutation, further studies are needed to assess whether the loss of the neighboring genes could modify the phenotype of carriers. There was complete absence of nuclear staining in the two HPT-JT-related tumors available. The finding of the first rearrangement affecting the CDC73 gene warrants screening for this tumor suppressor gene inactivation mechanism not only in high-risk CDC73 point mutation-negative HPT-JT families, but also in FIHP patients.     

Penetrance and clinical consequences of a gross SDHB deletion in a large family

Mutations in the gene encoding subunit B of the mitochondrial enzyme succinate dehydrogenase (SDHB) are inherited in an autosomal dominant manner and are associated with hereditary paraganglioma (PGL) and pheochromocytoma. The phenotype of patients with SDHB point mutations has been previously described. However, the phenotype and penetrance of gross SDHB deletions have not been well characterized as they are rarely described. The objective was to describe the phenotype and estimate the penetrance of an exon 1 large SDHB deletion in one kindred. A retrospective and prospective study of 41 relatives across five generations was carried out. The main outcome measures were genetic testing, clinical presentations, plasma catecholamines and their O -methylated metabolites. Of the 41 mutation carriers identified, 11 were diagnosed with PGL, 12 were found to be healthy carriers after evaluation, and 18 were reportedly healthy based on family history accounts. The penetrance of PGL related to the exon 1 large SDHB deletion in this family was estimated to be 35% by age 40. Variable expressivity of the phenotype associated with a large exon 1 SDHB deletion was observed, including low penetrance, diverse primary PGL tumor locations, and malignant potential.     

Novel mutation of TBX3 in a Japanese family with ulnar-mammary syndrome: implication for impaired sex development

We report on a Japanese family (two brothers and their mother) with ulnar-mammary syndrome (UMS). Clinical features included hypoplasia or aplasia of upper limbs on the ulnar side in the three affected individuals, micropenis with or without cryptorchidism, and hypoplastic nipples in the brothers; and hypoplastic mammary glands and nipples, poor perspiration, and bicornuate uterus in the mother. Endocrine studies performed for the underdeveloped external genitalia when the brothers were 11 6/12 and 7 2/12 years old, respectively, indicated low to low-normal responses of luteinizing hormone (LH) and follicle stimulating hormone (FSH) to gonadotropin releasing hormone stimulation tests (elder brother: LH = < 0.2 --> 2.2 IU/L, FSH = 0.6 --> 2.2 IU/L; younger brother: LH = < 0.2 --> 3.3 IU/L, FSH = 0.7 --> 4.4 IU/L) and normal testosterone responses to human gonadotropin stimulation tests (elder brother: < 0.5 --> 8.8 nmol/L; younger brother: < 0.5 --> 6.3 nmol/L). Testosterone enanthate therapy (25 mg/dose IM twice) was effective in the brothers, with penile length increase being similar between the brothers (approximately 5 mm/dose) and 23 age-matched boys with idiopathic micropenis (mean 4.4 mm/dose, range 2.5-7.5 mm/dose). Sequence analysis of the TBX3 gene showed a novel heterozygous nonsense mutation (A817T, K273X) in exon 4 of the three patients. The results are consistent with the previous finding that UMS is caused by haploinsufficiency of TBX3, and imply that mild gonadotropin deficiency may be the primary cause for underdeveloped external genitalia in males with UMS.     

Gardner syndrome in a man with an interstitial deletion of 5q

Chromosome analysis of blood cells from a 42-year-old white male with mental retardation, colon carcinoma, horseshoe kidney, absence of left lobe of the liver, agenesis of the gallbladder, and possible Gardner syndrome revealed a constitutional marker chromosome due to del(5)(q13q15) or del(5)(q15q22). A polymorphic chromosome #22 with enlarged satellites was inherited from the father, who is phenotypically normal, and was probably unrelated to the congenital malformations. This is the first report of a Gardner syndrome patient with an interstitial deletion of 5q.     

A novel interstitial deletion of KAL1 in a Japanese family with Kallmann syndrome

We identified a novel interstitial deletion that spanned from exons 5 to 10 of KAL1 in two Japanese brothers with X-linked Kallmann syndrome (KS; MIM no. 308700). Both brothers had hypogonadism, unilateral renal agenesis, and disturbance of the sense of smell, but they had no other neurological manifestations, including mental disturbance. Their mother was confirmed to be an asymptomatic carrier, by use of a comparative multiplex polymerase chain reaction (PCR) analysis. The present patients are further examples of patients with KS without mental disturbance caused by a mutation confined to KAL1. Received: March 17, 2000 / Accepted: May 9, 2000     

Holt-Oram syndrome associated with the hypoplastic left heart syndrome

We present the first case of Holt-Oram syndrome associated with the lethal congenital heart defect of hypoplastic left heart syndrome. The possible pathophysiological link is explored and the need for careful genetic and cardiologic evaluation in these patients is reiterated.