The pattern of inheritance of X-linked traits is not dominant or recessive, just X-linked

Our modern concepts of genetic inheritance originated nearly a century ago. Early concepts of dominant and recessive inheritance were developed in insects and were subsequently applied to sex-linked inheritance in mammals. Years of clinical experience, however, suggest that the modern-day rules for X-linked dominant and recessive diseases do not explain why so many female carriers of X-linked 'recessive' disorders have an abnormal phenotype. In a review of 32 X-linked diseases we revealed an unexpectedly high degree of intermediate disease penetrance in females that cannot be explained by existing concepts. We recommend that the terms 'dominant' and recessive' be abandoned and that these disorders be referred to as X-linked. In this review we will present modified rules for X-linked inheritance and propose hypotheses related to the potential mechanisms that may explain differences in disease expression in females.Conclusion: Past assumptions regarding factors that may affect phenotype in heterozygous females do not capture the extraordinarily variable expressivity of X-linked disorders in females and need to be revisited.     

Early onset lymphoedema,recessive form — a new form of genetic lymphoedema syndrome

We report on two brothers with chronic congenital lymphoedema. Besides the oedemas of limbs we found an unusual facial appearance, abnormalities of external genitals as a deformation sequence resulting from intrauterine oedemas and intestinal lymphoedema. This X-linked or autosomal recessive trait may be a new entity, to be differentiated from other genetic lymphoedema syndromes, the so-called familial protein-losing enteropathy, and dominantly inherited intestinal lymphangiectasia. A prominent sign of the syndrome is chemosis and injection of conjunctiva.     

Autosomal dominant inheritance of hypercalciuria

We examined 37 first and second degree relatives of 10 children with hypercalciuria. In 2 families only the index patient was affected, while in 8 others one of the parents was hypercalciuric; in the total of 47 persons examined 23 cases of idiopathic hypercalciuria could be identified. None of the subjects was hypercalcemic. The pedigrees suggest autosomal dominant inheritance of the trait.Dedicated to Prof. Dr. H.-R. Wiedemann on the occasion of his 65th birthday     

Genetic analysis of isolated persistent hypermethioninemia with dominant inheritance

We describe a type of mild hypermethioninemia due to a point mutation in the MATA1 gene, which was inherited dominantly in a family. Three patients coming from the same family pedigree were detected by the presence of isolated hypermethioninemia on a mass-screening program. The measurement of methionine adenosyltransferase (MAT) activity in a patient's liver revealed a partial deficiency of hepatic MAT with a reduction in the Km for methionine. Single strand conformation polymorphism (SSCP) analysis and direct sequencing of the patients' genomic DNA revealed a G to A mutation at nucleotide 791 that converts Arg-264 to His (R264H) in one allele of MATA1 gene. The other allele was normal in all the patients examined. Gene tracking in the family revealed that the hypermethioninemia is associated with heterozygosity for the R264H mutation in the MATA1 gene.     

Absence of testicular steroid sulphatase activity in a boy with recessive X-linked ichthyosis and testicular maldescent

We present a 14-year-old boy with recessive X-linked ichthyosis in whom only one testis could be found. In this apparently normal testis, a lack of activity of the enzyme steroid sulphatase was demonstrated. Several male patients with recessive X-linked ichthyosis have been reported to have testicular diseases, and it is suggested that this may be related to the absence of testicular steroid sulphatase activity.Abbreviations RXLI recessive X-linked ichthyosis - STS steroid sulphatase     

X连锁显性遗传性低磷血症性佝偻病诊治专家共识

X连锁显性遗传性低磷血症性佝偻病(OMIM307800)为罕见的遗传病,是低磷血症性佝偻病最常见的类型,患病率约为1/20 000^ [1],1937年由Albright等^ [2]首次报道。患者多在开始走路、骨骼逐渐负重后才被发现,如果不能及早、正确治疗,将导致骨骼残疾及生长障碍,严重损害患者及其家庭的生存质量,如果及早诊治,预后良好。     

X-连锁淋巴组织增殖综合征的临床表型和诊断

X-连锁淋巴组织增殖综合征(XLP)是一种少见的、常常是致死性的原发性免疫缺陷病,可由EB病毒感染诱发,表现为爆发性传染性单核细胞增多症、丙种球蛋白异常血症和淋巴增殖性疾病以及淋巴瘤.本病主要由编码淋巴信号活化分子相关蛋白(SAP)、X-连锁凋亡抑制因子(XIAP)和IL-2诱导的T细胞激酶(ITK)基因的突变引起.基因序列分析是确诊XLP的依据;SAP、XIAP、ITK蛋白的表达也可以作为筛查XLP的手段.家族史是需要考虑的主要客观指标,其他诊断标准包括患儿的临床表现、EB病毒感染后的EBNA抗体检测等.     

Studies of malformation syndromes of man XXXIII: The FG syndrome. An X-linked recessive syndrome of multiple congenital anomalies and mental retardation

Three brothers and two of their male first cousins were affected with a previously apparently undefined multiple congenital anomaly, mental retardation syndrome which was designated the FG syndrome and which consists of variable growth problems with a disproportionately large head, characteristic appearance and minor anomalies, imperforate anus, mild to severe mental retardation and congenital hypotonia; pyloric stenosis, hypoplastic left heart, generalized dilatation of the urinary tract, cutaneous syndactyly of third and fourth fingers, and severe craniosynostosis were seen each in 1 patient. Partial agenesis of the corpus callosum seen in 1 patient is suspected in another on the basis of EEG abnormalities. 1 boy died neonatally with congenital heart disease, and 2 others of pneumonia at 20 and 23 months. The FG syndrome is an X-linked recessive condition; heterozygotes appear grossly normal.Paper No. 1705 from the University of Wisconsin Genetics Laboratory     

The severe recessive form of pseudoachondroplastic dysplasia

Genetic and clinical heterogeneity within the category of pseudoachondroplastic dysplasia is discussed. Clinical and radiological findings are presented in a family where 4 out of 7 siblings, aged between 3 and 10 years, had a severe form of the condition. The parents had short stature without any signs of pseudoachondroplastic dysplasia. Inheritance in this family appears to be recessive, with a possibility that the abnormal allele may be partially manifest in heterozygotes.     

Martsolf syndrome in a brother and sister: clinical features and pattern of inheritance

A brother and sister with Martsolf syndrome are reported. The main characteristics of the syndrome are mental retardation, short stature, cataracts, hypogonadism and craniofacial anomalies including microcephaly, maxillary retrusion, pouting mouth, malaligned teeth and mildly dysplastic pinnae. The metacarpal and phalangeal bones are short. The occurrence of Martsolf syndrome in sibs of opposite sex suggests autosomal recessive inheritance.Abbreviations MCPPP metacarpal phalangeal pattern profile - FSH follicle stimulating hormone - LH futeinizing hormone - TORCH toxoplasmosis, rubella, cytomegaly and herpes     

X连锁Alport综合征女性患者临床表型差异的可能机制

Alport综合征(Alport syndrome,AS)是以血尿、感音神经性耳聋和进行性肾功能减退为临床特点的遗传性肾脏疾病,X连锁显性遗传(X-linked Alport syndrome,XLAS)为其主要遗传方式,因COL4A5和(或)COL4A6基因突变所致。X连锁Alport综合征女性患者临床表型差异很大,轻者无症状或仅表现为镜下血尿,重者有慢性肾功能衰竭,尤其是来自同一家系的女性患者临床表型可以明显不同,这种现象不能完全用COL4A5基因突变类型来解释。近年来,研究显示XLAS女性患者临床表型的差异与COL4A5突变mRNA及基底膜a5(Ⅳ)链的表达量相关,而COL4A5突变mRNA及基底膜a5(Ⅳ)链的表达量不同的机制可能与X染色体失活有关,其他表观遗传学调控方式也可能参与其中。该文就X连锁Alport综合征女性患者临床表型差异的可能机制进行了文献综述。     

X-linked agammaglobulinemia, growth hormone deficiency and delay of growth and puberty

Buzi F, Notarangelo LD, Plebani A, Duse M, Parolini O, Monteleone M, Ugazio AG. X-linked agammaglobulinemia, growth hormone deficiency and delay of growth and puberty. Acta Paediatr 1994;83:99–102. Stockholm. ISSN 0803–5253
Coinheritance of X-linked agammaglobulinemia and growth hormone deficiency (XLA/GHD) has been classified as an independent primary immune deficiency. We evaluated the pattern of growth and endocrine function in seven XLA subjects (ages 10.9–20.1 years); four belonged to two different XLA pedigrees and three represented sporadic XLA cases. Three had reached adulthood (final stature 176.0, 173.5 and 165.0 cm, respectively) and their retrospective growth showed delay in growth and puberty during adolescence. In the other four subjects, growth hormone production was measured by growth hormone pharmacological stimulation tests (clonidine, arginine): three of four patients had insufficient growth hormone responses (peak growth hormone < 10 μg/l); all three had delayed puberty; their growth hormone responses increased after "priming" with testosterone, reaching values > 10 μg/l in two of them and allowing diagnosis of "true" growth hormone deficiency in the third. The fourth was a normally growing subject who showed a normal growth hormone response both before and after testosterone priming. Six out of the seven subjects showed a growth pattern consistent with delay in growth and puberty. Our results suggest that true XLA/GHD is rarer than previously supposed and that subnormal responses to growth hormone stimulation tests may be found without sex steroid priming of the test in adolescence. The most probable growth pattern in XLA appears to be delay in growth and puberty, as has already been described for other chronic diseases.     

Further delineation of the ichthyosis follicularis,atrichia, and photophobia syndrome

We describe an 18-month-old male infant suffering from the ichthyosis follicularis, atrichia, and photophobia (IFAP) syndrome and further delineate the clinical phenotype. Severe retardation of growth and psychomotor development, chill-like seizures, bronchial asthma, urticaria, a proneness to skin infections and transient nail dystrophy observed in our patient are nonobligatory manifestations of this disorder. Histological examination of the atrichia revealed poorly developed, shortened hair follicles and a complete absence of sebaceous glands. The sex ratio of published cases suggests an X-linked recessive inheritance. The marked clinical variability of the IFAP syndrome might be the expression of a contiguous gene defect.Presented in part at the Fifth International Congress of Paediatric Dermatology, Milan/Italy, 11–15 July, 1989     

X-染色体连锁的凋亡抑制蛋白对新生小鼠脑缺氧缺血后细胞色素C释放的影响

目的 探讨X-染色体连锁的凋亡抑制蛋白(XIAP)对未成熟脑缺氧缺血(HI)后细胞色素C从线粒体释放的影响.方法 新生9日龄转基因XIAP过度表达C57BL/6小鼠(XIAP组)及同期野生型9日龄C57BL/6小鼠(野生组)在HI后不同时间点处死取脑,部分脑组织进行手工匀浆后差速离心分离胞浆和线粒体成分进行Western蛋白印迹,部分脑组织进行细胞色素C免疫组化染色.结果 Western蛋白印迹显示,HI后24 h缺血侧脑组织线粒体中细胞色素C的含量较对侧减少,而胞浆中细胞色素C的含量较对侧增加(细胞色素C从线粒体释放);XIAP组脑组织线粒体中细胞色素C释放量明显少于野生组.免疫组化结果显示HI后3 h、24 h,XIAP组大脑皮层和海马CAI区细胞色素C阳性细胞数明显低于野生组.结论 XIAP过度表达可抑制HI后细胞色素C从线粒体向胞浆的释放.     

X连锁非特异性精神发育迟滞相关基因IL1RAPL1功能研究进展

IL1RAPL1基因是X连锁非特异性精神发育迟滞(X-linked nonspecific mental retardation,MRX)的相关基因之一,但其致病机制至今尚未完全明确。IL1RAPL1基因编码的白细胞介素1受体辅助蛋白样1(interleukin-1 receptor accessory protein...     

Survival to adulthood and dominant inheritance of platyspondylic skeletal dysplasia,Torrance-Luton type

We present a second family with survival to adulthood and dominant transmission of the Torrance-Luton type of platyspondylic chondrodysplasia, and demonstrate the radiographs at different ages together with radiographs and further data of the first family which was published in the Journal of Pediatrics (J Pediatr 136:411–413). Two families are described with survival to adulthood and dominant transmission of the Torrance-Luton type of platyspondylic chondrodysplasia. Although lethality is increased in patients with this disorder, mild expressions of the genetic defect are compatible with survival into adulthood. The heterogeneous group of platyspondylic lethal skeletal dysplasias (PLSD) originally included thanatophoric dysplasias (TD1/2: MIM 187600, 187100) as the most common forms of this condition, as well as TD variants San Diego type (PLSD-SD: MIM 270230) and Torrance-Luton type (PLSD-TL: MIM 151210). Fibroblast growth factor receptor 3 (FGFR3) gene mutations have been detected in TD1/2 and PLSD-SD. Molecular studies in one of our two families with the Torrance-Luton type did not disclose mutations in the FGFR3 coding region, suggesting that this type of platyspondylic chondrodysplasia is not a thanatophoric dysplasia variant. In contrast to TD1/2 and PLD-SD, the Torrance-Luton type platyspondylic dysplasia is compatible with survival to adulthood.     

Tumor immune surveillance defect of X-linked severe combined immunodeficiency is not Epstein-Barr virus specific

Immunodeficient patients are at an increased risk of developing Epstein-Barr virus (EBV) associated lymphomas. We report a patient with X-linked severe combined immunodeficiency (X-SCID), who presented with an EBV-negative, B-cell non-Hodgkin lymphoma. The tumor did not resolve with chemotherapy or rituximab, but only after recovery of functional donor T-cells cell following hematopoietic stem cell transplantation (HSCT). This case illustrates that the cancer predilection associated with immunodeficient hosts may not be a specific immune defect in the recognition of viral specific antigens, and it could be a defect in immune surveillance necessary for elimination of cells with abnormalities in proliferation, function and/or apoptosis.     

To drain or not to drain,that is the question

Spontaneous pneumothorax is an uncommon problem in childhood. However, it is frequent enough that most paediatricians will encounter this at some point in their careers. Traditional management for children and young people with a moderate to large pneumothorax has involved either needle thoracocentesis, chest drain insertion or both. However, recent clinical trials have suggested that a conservative approach may be possible and in some circumstances preferable to immediate intervention. This short article offers a suggested framework for management of spontaneous pneumothorax in children and young people.     

To trach or not to trach,that is the question

Progressive neuromuscular disease requires increasing degrees of respiratory support to sustain life. Each step from intermittent to continuous—and noninvasive to invasive—ventilation requires thoughtful consideration based on the goals of the patient and family, and the inherent benefits and burdens of the treatment. Tracheostomy, in particular, should not be viewed as an inevitable next step when less permanent or invasive methods prove insufficient. Like other modes of respiratory support, tracheostomy may represent a bridge to recovery of pulmonary function, or a stabilizing action in the hope that novel therapies may prove beneficial. In other situations, tracheostomy represents a destination therapy, necessitating consideration of the implications of chronic mechanical ventilation. Institutional, social, and financial considerations may affect decisions related to tracheostomy, as may implicit bias regarding quality of life. The complexity of such care and decisions highlight the need for optimal palliative care throughout the patient’s life.