Multiple epiphyseal dysplasia tarda

The pedigree is described of a Mexican family with multiple epiphyseal dysplasia tarda (MEDT) suggestive of autosomal recessive inheritance. The parents were probably consanguineous and three of the five siblings of the propositus had the disease. The affected individuals had a total of 13 normal offspring, which makes dominant inheritance quite unlikely. Although most cases of MEDT follow an autosomal dominant pattern there are several families like that presented here, which suggests that this condition is heterogeneous.     

Exome sequencing revealed a novel splice site variant in the ALX1 gene underlying frontonasal dysplasia

Frontonasal dysplasia (FND) is a heterogeneous group of disorders characterized by hypertelorism, telecanthus, broad nasal root, wide prominent nasal bridge, short and wide nasal ridge, broad columella and smooth philtrum. To date one X‐linked and three autosomal recessive forms of FND have been reported in different ethnic groups. We sought to identify the gene responsible for FND in a consanguineous Pakistani family segregating the disorder in autosomal recessive pattern. Genome‐wide homozygosity mapping using 250KNsp array revealed five homozygous regions in the selected affected individuals. Exome sequencing found a novel splice acceptor site variant (c.661‐1G>C: NM_006982.2) in ALX1. Sanger sequencing confirmed the correct segregation of the pathogenic variant in the whole family. Our study concludes that the splice site variant identified in the ALX1 gene causes mild form of FND.     

Fibular hypoplasia and complex brachydactyly (Du Pan syndrome) in an inbred Pakistani kindred

A Pakistani kindred comprising 7 generations contained 7 men and 2 women with fibular hypoplasia and complex brachydactyly (syn: Du Pan syndrome). Analysis of the pedigree is strongly suggestive of autosomal recessive inheritance. The average inbreeding coefficient (F) for the affected persons was found to be significantly greater than that for unaffected persons in the pedigree and consanguineous loops could account for all affected persons being homozygous for the abnormal allele.     

Wisconsin consanguinity studies. II: Familial adenocarcinomatosis

Predisposition to carcinoma in certain families has been recognized as an autosomal dominant trait. We describe a large pedigree (over 1,000 persons) including ten consanguineous unions with inbreeding coefficients from 0.02 to 0.17. Persons of consanguineous parentage accounted for 16 of 18 cases of adenocarcinoma (most of which were colorectal). Three women with breast cancer were relatives but not of consanguineous parentage. Only six of 36 persons with a malignancy of any kind were unrelated spouses, and only one of these had adenocarcinoma. Multiple primary carcinomas and/or early age-of-onset were observed only in products of consanguinity. In this extended family, the occurrence of adenocarcinoma appears to segregate as an autosomal recessive trait. It is conceivable that a proto-oncogene is segregating in this family and that, in some members, consanguineous unions have produced homozygosity for this oncogene.     

Elsahy-Waters syndrome: Evidence for autosomal recessive inheritance

Elsahy-Waters or branchioskeletogenital syndrome is a rare MCA/MR syndrome characterized by moderate mental retardation, hypospadias and characteristic craniofacial morphology, which includes brachycephaly, facial asymmetry, exotropia, hypertelorism/telechantus, broad nose, concave nasal ridge, underdeveloped midface, prognathism, and radicular dentin dysplasia. Here we report on a 44-year-old woman and her 45-year-old brother, born to consanguineous parents, who show a striking resemblance to the earlier described patients. The hitherto reported patients were male and in one pedigree parents were consanguineous. The present report of an affected woman and her brother, born to consanguineous parents, supports autosomal recessive inheritance of this condition. We provide a short review of all previously reported patients with Elsahy-Waters syndrome and related entities.     

Oculoauriculofrontonasal syndrome (OAFNS) in a nine‐month‐old male

We report a nine‐month‐old Caucasian male with features seen in oculoauriculovertebral spectrum (OAVS) and frontonasal dysplasia sequence (FND) born to normal, non‐consanguineous parents and review the literature. His malformations included a left pre‐auricular skin tag, severely hypoplastic right pinna without an external canal, severely everted and hypoplastic left upper eyelid, bilateral cleft lip and palate, bifid broad nasal tip, ocular hypertelorism, micrognathia, hypoplastic mandible, an extra cervical rib on the left, hemivertebrae at T3–4, agenesis of the posterior corpus callosum with a midline lipoma, and an extra renal pelvis. This constellation of anomalies is consistent with the diagnosis of oculoauriculofrontonasal syndrome (OAFNS) which appears to be a distinct condition from either OAVS or FND but with overlapping features. © 2001 Wiley‐Liss, Inc.     

A novel mitochondrial point mutation in a maternal pedigree with sensorineural deafness

We have detected a novel mitochondrial mutation in a maternal pedigree, at least 13 of whose members have sensorineural hearing loss of varying severity, but who exhibit no other pathological features. The mutation, at np 7445, converts the 3′ terminal T residue of tRNA-ser(UCN) to a C, and also brings about a silent alteration to the COI stop codon. The mutation destroys an XbaI site, within which a second mutation, at np 7444, has previously been reported in association with Leber's hereditary optic neuropathy. Predominantly mutant mtDNA was found in all 13 family members surveyed, whether or not they are overtly affected by deafness, and some individuals appeared homoplasmic, within the limits of detection. The novel mutation was not found in over 600 normal controls, nor in any of 27 other maternally unrelated individuals with deafness Other mutations found in mitochondrial disorders were also absent from this pedigree. © 1994 Wiley-Liss, Inc.     

Analysis of TGFBI gene mutation in a Chinese pedigree affected with lattice corneal dystrophyCSCD

Objective: To explore the clinical features and mutation of TGFBI gene in a Chinese pedigree affected with lattice corneal dystrophy (LCD). Methods: Genomic DNA was extracted from 35 members including 11 patients from the pedigree. The 17 exons and splicing region of introns of the TGFBI gene were amplified by PCR. The products were directly sequenced and compared with GenBank database to identify potential mutation. Bioinformatic analysis was carried out to predict the effect of mutation on proteins. Results: A heterozygous mutation (p. R124C) was found in exon 4 of the TGFBI gene in all patients from the pedigree but not among unaffected members. The mode of inheritance of corneal dystrophy in this pedigree was identified as autosomal dominant. Bioinformatics analysis predicted that the p. R124C mutation may be functionally deleterious. The phenotype of corneal dystrophy in the pedigree was determined to be LCD I type. Conclusion: The p. R124C mutation of the TGFBI gene probably underlies the pathogenesis of LCD in this Chinese pedigree. Genetic testing can facilitate proper diagnosis of this type of corneal dystrophy. © 2018 MeDitorial Ltd. All rights reserved.     

Presumed homozygous Ehlers-Danlos syndrome type I in a highly inbred kindred

While studying an extended family of individuals with the Ehlers-Danlos (ED) syndrome type I, we found an affected male who was born to 2 affected consanguineous parents. This man had a more severe condition than that of his other affected relatives. Moreover, all 6 of his children were affected. Taking the pedigree data into account, the conditional probability of homozygosity for the ED gene in that patient was calculated as 97%. Some problems of the clinical and genetic approach to the recognition of the homozygous state in the ED syndrome are discussed using this family as an example.     

先天性厚甲症Ⅱ型一家系KRT17基因突变研究

目的 研究1个先天性厚甲症Ⅱ型家系的基因突变情况.方法 收集该家系的详细临床资料,外周血提取基因组DNA,PCR扩增KRT17热点突变区,通过PCR扩增产物直接测序方法对该家系患者、正常成员和100名无亲缘关系的正常人进行KRT17基因突变检测.结果 在该家系患者KRT17基因的第1外显子上发现了1个错义突变(296 T→C),导致KRT17的1A区亮氨酸由脯氨酸替代(L99P),而家系中正常成员和家系外100名正常对照中均未能发现该突变.结论 该家系患者的临床表现为KRT17发生突变(L99P)所致,结合文献复习证实部分PC-Ⅱ家系基因型与表现型之间存在一定相关性.

Abstract：

Objective To investigate the keratin 17 gene (KRT17)mutation in a pedigree with pachyonychia congenita type 2 (PC-Ⅱ ). Methods DNA was extracted from the blood samples of the patients, unaffected members of the pedigree, and 100 unrelated healthy controls. PCR was performed to amplify the hot spots in KRT17 gene. PCR products were directly sequenced to detect mutation. Results A heterozygous 296T--C mutation was found in all the affected members of this family, which resulted in the substitution of leucine by proline in codon 99 (L99P) in the 1A domain of the KRT17, but not in the healthy individuals from the family and the 100 unrelated controls. Conclusion The mutation of KRT17 may play a major role in the pathogenesis of this pedigree with pachyonychia congenita type 2.     

Opitz trigonocephaly syndrome

We report on a patient with Opitz trigonocephaly syndrome. The girl was the firstborn child of consanguineous parents and had trigonocephaly, apparent hypertelorism, upslanted palpebral fissures, strabismus, small nose with broad root, abnormally modeled ears, high palate, short neck with loose skin, polysyndactyly, and prominent clitoris and labia majora. In addition, a complex cardiovascular defect (Eisenmenger disease) was observed. The patient was mentally retarded.     

Alkaptonuria in the Trencín District of Czechoslovakia.

For several years the Clinical Genetics Research Laboratory at Martin, Czechoslovakia, has been studying alkaptonuria (AU) in the northern part of the District of Trencín in Slovakia. These affected individuals are part of a group of 103 alkaptonurics originated mostly in the mountainous parts of Slovakia. We report results of pedigree analyses; population and affected-family biochemical urine screening; estimation of inbreeding coefficient, of exogamy rate and of average marital distance and of calculation of the frequency of the AU allele, and of homozygotes and heterozygotes in this portion of the Trencín District. Twelve homozygotes were found, but seven originated from a single hamlet in which a founder effect - genetic drift and inbreeding - are thought to account for the high prevalence of AU.     

一个非综合征型唇腭裂家系的致病基因鉴定

目的对一个非综合征型唇腭裂家系进行分子遗传学研究,探寻其致病原因。方法对该家系成员进行详细的体格检查和既往史调查,排除综合征型唇腭裂。对该家系1例患儿的基因组DNA进行全外显子组测序及生物信息学分析。筛查到候选致病基因突变位点后,采用Sanger测序对该家系成员及100名健康对照个体进行共分离分析和人群验证分析。结果全外显子组测序及疾病共分离分析显示,该家系患者IRF6基因第4外显子存在c.253A>G(p.Cys85Arg)变异,且该突变未在健康对照个体中检出,文献尚未见报道。结论IRF6基因第4外显子c.253A>G错义变异是导致该家系发病的原因。     

Simpson-Golabi-Behmel syndrome with severe cardiac arrhythmias

We report on a family with 2 affected males with the X-linked Simpson-Golabi-Behmel (SGB) syndrome. The propositus was a 33-year-old man with pre- and postnatal overgrowth, "coarse" face with hypertelorism, broad nose, wide mouth, malposition of teeth, submucous cleft, accessory nipples, broad hands with hypoplastic index finger nails, and operated left postaxial hexadactyly. From the age of 26 years he suffered from severe tachyarrhythmias, requiring recurrent defibrillations. The brother of the propositus was macrosomic at birth and had a similar facial appearance. In addition he had a pyloric stenosis and a 3/6 systolic murmur. He died at age 4 months. Cardiac defects and conduction disturbances are major components of the SBG syndrome and can be responsible for death in early infancy and perhaps for cardiac arrest in the adult.     

Alkaptonuria in the Trenčín District of Czechoslovakia

For several years the Clinical Genetics Research Laboratory at Martin, Czechoslovakia, has been studying alkaptonuria (AU) in the northern part of the District of Tren?ín in Slovakia. These affected individuals are part of a group of 103 alkaptonurics originated mostly in the mountainous parts of Slovakia. We report results of pedigree analyses; population and affected-family biochemical urine screening; estimation of inbreeding coefficient, of exogamy rate and of average marital distance and of calculation of the frequency of the AU allele, and of homozygotes and jeterozygotes in this portion of the Tren?ín District. Twelve homozygotes were found, but seven originated from a single hamlet in which a founder effect – genetic drift and inbreeding – are thought to account for the high prevalance of AU.     

Alopecia universalis as a single abnormality in an inbred Pakistani kindred

A Pakistani kindred comprising 5 generations contained 9 males and 4 females with alopecia universalis as a single abnormality without any associated defects. The skin biopsy from the scalp showed hair follicles without hair. Analysis of the pedigree is strongly suggestive of autosomal recessive inheritance, and consanguineous loops could account for all affected persons being homozygous for the abnormal allele. © 1993 Wiley-Liss, Inc.     

Ectrodactyly with aplasia of long bones (OMIM; 119100) in a large inbred Arab family with an apparent autosomal dominant inheritance and reduced penetrance: clinical and genetic analysis

Ectrodactyly with aplasia of long bones syndrome is one of the most recognizable defects involving the extremities. We have studied a very large eight-generation consanguineous Arab family from the United Arab Emirates (UAE) with multiple severe limb anomalies resembling this condition (OMIM; 119100), for which the affected gene is unknown. The pedigree consists of 145 individuals including 23 affected (14 males/9 females) with limb anomalies. Of these, 18 had tibial aplasia (TA) usually on the right side. The expression of the phenotype was variable and ranged from bilateral to unilateral TA with ectrodactyly and other defects of the extremities. The mode of inheritance appears to be autosomal dominant with reduced penetrance. There were 10 consanguineous marriages observed in this pedigree. This could suggest possible pseudodominance due to high frequency of the mutant allele. Candidate loci for the described syndrome include GLI3 (OMIM: 165240) on 7p13, sonic hedgehog; (OMIM: 600725) on 7q36, Langer-Giedion syndrome (OMIM: 150230) on 8q24.1 and split-hand/foot malformation 3 (OMIM: 600095) on 10q24. In addition, bilateral tibial hemimelia and unilateral absence of the ulna was previously observed to co-segregate with deletion of 8q24.1. Two-point linkage and haplotype analyses did not show the involvement of the above regions in this family.     

Challenges and solutions for gene identification in the presence of familial locus heterogeneity

Next-generation sequencing (NGS) of exomes and genomes has accelerated the identification of genes involved in Mendelian phenotypes. However, many NGS studies fall short of identifying causal variants, with estimates for success rates as low as 25% for uncovering the pathological variant underlying disease etiology. An important reason for such failures is familial locus heterogeneity, where within a single pedigree causal variants in two or more genes underlie Mendelian trait etiology. As examples of intra- and inter-sibship familial locus heterogeneity, we present 10 consanguineous Pakistani families segregating hearing impairment due to homozygous variants in two different hearing impairment genes and a European-American pedigree in which hearing impairment is caused by four variants in three different genes. We have identified 41 additional pedigrees with syndromic and nonsyndromic hearing impairment for which a single previously reported hearing impairment gene has been identified but only segregates with the phenotype in a subset of affected pedigree members. We estimate that locus heterogeneity occurs in 15.3% (95% confidence interval: 11.9%, 19.9%) of the families in our collection. We demonstrate novel approaches to apply linkage analysis and homozygosity mapping (for autosomal recessive consanguineous pedigrees), which can be used to detect locus heterogeneity using either NGS or SNP array data. Results from linkage analysis and homozygosity mapping can also be used to group sibships or individuals most likely to be segregating the same causal variants and thereby increase the success rate of gene identification.     

Cardio-cutaneous syndrome (the "LEOPARD" syndrome). Review of the literature and a new family

Numerous reports of familial cardiac disorders associated with abnormalities of cutaneous pigmentation have appeared in the literature. In some of these there have been other somatic malformations including retardation of growth and anomalous development of the genitalia. In this paper we review the literature and describe another family with multiple lentigines occurring in six members out of eight examined. They were reported to occur in 10 other members not seen by us. The trait showed an autosomal dominant mode of inheritance and appeared to be transmitted by affected fathers. In previous reports transmission has usually been through an affected mother. In five of the six patients examined, only skin abnormalities were detected, but in the propositus the lentigines were associated with retardation of growth, hypertelorism, abnormal genitalia and complete atrioventricular block. The possible explanations for the lack of pleomorphy in other members of the family are discussed.     

Consanguinity among the Kuwaiti population

A total of 5,007 Kuwaitis were ascertained to study the incidence of consanguineous marriages during 1983. The rate of consanguineous mating was found to be 54.3% with estimated population incidence rates 52.9 to 55.7%. First cousin marriages were the most frequent type. The average inbreeding coefficient was 0.0219 which could be considered high.