The gene for achondroplasia maps to the telomeric region of chromosome 4p.

Achondroplasia is the most common type of genetic dwarfism. It is characterized by disproportionate short stature and other skeletal anomalies resulting from a defect in the maturation of the chondrocytes in the growth plate of the cartilage. We have now mapped the achondroplasia gene near the telomere of the short arm of chromosome 4 (4p16.3), by family linkage studies using 14 pedigrees. A positive lod score of z = 3.35 with no recombinants was obtained with an intragenic marker for IDUA. This localization will facilitate the positional cloning of the disease gene.

Disruption of human limb morphogenesis by a dominant negative mutation in CDMP1.

Chondrodysplasia Grebe type (CGT) is an autosomal recessive disorder characterized by severe limb shortening and dysmorphogenesis. We have identified a causative point mutation in the gene encoding the bone morphogenetic protein (BMP)-like molecule, cartilage-derived morphogenetic protein-1 (CDMP-1). The mutation substitutes a tyrosine for the first of seven highly conserved cysteine residues in the mature active domain of the protein. We demonstrate that the mutation results in a protein that is not secreted and is inactive in vitro. It produces a dominant negative effect by preventing the secretion of other, related BMP family members. We present evidence that this may occur through the formation of heterodimers. The mutation and its proposed mechanism of action provide the first human genetic indication that composite expression patterns of different BMPs dictate limb and digit morphogenesis.

Detection of circulating tumour cells in peripheral blood with an automated scanning fluorescence microscope.

We have developed an automated, highly sensitive and specific method for identifying and enumerating circulating tumour cells (CTCs) in the blood. Blood samples from 10 prostate, 25 colorectal and 4 ovarian cancer patients were analysed. Eleven healthy donors and seven men with elevated serum prostate-specific antigen (PSA) levels but no evidence of malignancy served as controls. Spiking experiments with cancer cell lines were performed to estimate recovery yield. Isolation was performed either by density gradient centrifugation or by filtration, and the CTCs were labelled with monoclonal antibodies against cytokeratins 7/8 and either AUA1 (against EpCam) or anti-PSA. The slides were analysed with the Ikoniscope robotic fluorescence microscope imaging system. Spiking experiments showed that less than one epithelial cell per millilitre of blood could be detected, and that fluorescence in situ hybridisation (FISH) could identify chromosomal abnormalities in these cells. No positive cells were detected in the 11 healthy control samples. Circulating tumour cells were detected in 23 out of 25 colorectal, 10 out of 10 prostate and 4 out of 4 ovarian cancer patients. Five samples (three colorectal and two ovarian) were analysed by FISH for chromosomes 7 and 8 combined and all had significantly more than four dots per cell. We have demonstrated an Ikoniscope based relatively simple and rapid procedure for the clear-cut identification of CTCs. The method has considerable promise for screening, early detection of recurrence and evaluation of treatment response for a wide variety of carcinomas.

Osteogenesis imperfecta type IV. Biochemical confirmation of genetic linkage to the pro alpha 2(I) gene of type I collagen.

Fibroblasts from two affected members of a large pedigree in which osteogenesis imperfecta (OI) type IV is genetically linked to the pro alpha 2(I) gene of type I collagen synthesize two populations of pro alpha 2(I) chains. One population is normal; the second population appears to have a deletion of about 10 amino acid residues from the middle of the triple helical domain. The mutation in pro alpha 2(I) causes increased posttranslational modification in the amino-terminal half of some pro alpha 1(I) chains, lowers the melting temperature of type I collagen molecules that incorporate a mutant pro alpha 2(I) chain, and prevents or delays the secretion of those molecules from fibroblasts in cell culture. On the basis of this study and linkage studies in additional families, it appears that the OI type IV phenotype is often the result of heterozygosity for mutations in pro alpha 2(I) that alter the triple helical structure of type I collagen.

Restriction fragment length polymorphism associated with the pro alpha 2(I) gene of human type I procollagen. Application to a family with an autosomal dominant form of osteogenesis imperfecta.

One cloned complementary DNA and one genomic subclone were used to detect restriction fragment length polymorphism associated with the pro alpha 2(I) gene for human type I procollagen. The restriction fragments obtained from examination of 30-122 chromosomes confirmed previous indications that the pro alpha 2(I) gene is found in a single copy in the human haploid genome. One highly polymorphic site was detected with EcoRI in the 5'-half of the gene. The restriction site polymorphism at the site had an allelic frequency of 0.38, and it generated two fragments of 10.5 and 3.5 kilobase in homozygous individuals. The restriction fragment length polymorphism generated at the EcoRI site was used to study affected and non-affected individuals in four generations of a family with an autosomal dominant form of osteogenesis imperfecta. The data demonstrated a linkage of the phenotype to a pro alpha 2(I) allele with a lod score of 2.41 at a recombination fraction (theta) of 0. The data therefore provided presumptive evidence that osteogenesis imperfecta in this family is caused by a mutation in the pro alpha 2(I) gene or some contiguous region of the genome. The relatively high frequency of polymorphism at the EcoRI site makes it useful for studying a broad range of genetic disorders in which mutations in type I procollagen are suspected. In addition, the polymorphic site should provide useful markers for linkage studies with other loci located on human chromosome 7.

Family history of severe cardiovascular disease in Marfan syndrome is associated with increased aortic diameter and decreased survival.

OBJECTIVES: We attempted to determine whether a family history of severe cardiovascular disease in patients with the Marfan syndrome is associated with increased aortic dilation or decreased survival, or both. BACKGROUND: The prognostic importance of a family history of severe cardiovascular disease in patients with the Marfan syndrome has been incompletely examined. We hypothesized that such a family history would correlate with increased aortic dilation and would be associated with decreased survival. METHODS: One hundred eight affected patients and 48 unaffected family members from 33 multigenerational families with the Marfan syndrome underwent echocardiographic measurement of the aortic root, arch and mid-abdominal aorta. Date of birth and age at death ascertained from family pedigrees were used to perform life table analysis and estimate survival. RESULTS: Aortic root and arch diameters were significantly greater in patients with a family history of severe cardiovascular disease than in patients without such a family history. Of subjects in the highest quartile for aortic size, > 80% had such a family history in contrast to < 10% of those in the lowest quartile (chi-square 57.37, p < 0.00001). Mean age at death and cumulative probability of survival were significantly lower in patients with such a family history. CONCLUSIONS: Among patients with the Marfan syndrome, aortic dilation is greater and life expectancy shorter in those with a family history of severe cardiovascular manifestations. These data suggest that such a family history is an important risk factor for cardiovascular events in patients with the Marfan syndrome.

Neurologic correlates of osteogenesis imperfecta.

The neurologic status of ten patients with osteogenesis imperfecta (OI) was evaluated. Four patients with mild OI (type I) had normal neurologic findings and normal computed tomographic scans. Three of these four patients had macrocephaly. All six patients with severe OI (type III) had cortical atrophy on computed tomographic scan and three were also macrocephalic.

Life expectancy in the Marfan syndrome.

Data reported in 1972 indicated that lifespan in patients with the Marfan syndrome is markedly shortened, and that most deaths are cardiovascular. This study was performed to determine whether survival in the Marfan syndrome has changed since 1972, and to discern whether treatment (medical or surgical) has altered prognosis. Survival curves were generated on 417 patients from 4 referral centers, with a definite diagnosis of the Marfan syndrome. Birth date, age at death, cardiovascular surgery, or treatment with beta blockers, or any combination of these, were included in the analysis. Forty-seven of 417 patients died. Mean age at death (41 +/- 18 years) was significantly increased compared with age in 1972 (32 +/- 16 years, p = 0.0023). Median (50%) cumulative probability of survival in 1993 was 72 years compared with 48 years in 1972. Of 112 surgically treated patients, 10-year probability of survival was 70%. Patients undergoing surgery after 1980 enjoyed significantly increased survival than patients who had undergone operation before 1980 (p = 0.008). In conclusion, life expectancy for patients with the Marfan syndrome has increased > 25% since 1972. Reasons for this dramatic increase may include (1) an overall improvement in population life expectancy, (2) benefits arising from cardiovascular surgery, and (3) greater proportion of milder cases due to increased frequency of diagnosis. Medical therapy (including beta blockers) was also associated with an increase in probable survival.

A common FGFR3 gene mutation is present in achondroplasia but not in hypochondroplasia.

Achondroplasia is the most common type of genetic dwarfism. It is characterized by disproportionate short stature and other skeletal anomalies resulting from a defect in the maturation of the chondrocytes in the growth plate of the cartilage. Recent studies mapped the achondroplasia gene on chromosome region 4p16.3 and identified a common mutation in the gene encoding the fibroblast growth factor receptor 3 (FGFR3). In an analysis of 19 achondroplasia families from a variety of ethnic backgrounds we confirmed the presence of the G380R mutation in 21 of 23 achondroplasia chromosomes studied. In contrast, the G380R mutation was not found in any of the 8 hypochondroplasia chromosomes studied. Furthermore, linkage studies in a 3-generation family with hypochondroplasia show discordant segregation with markers in the 4p16.3 region suggesting that at least some cases of hypochondroplasia are caused by mutations in a gene other than FGFR3.

Psychosocial functioning in the Ehlers-Danlos syndrome.

Ehlers-Danlos Syndrome (EDS) is a group of related genetic disorders of connective tissue presenting with joint hypermobility, skin extensibility, and tissue fragility. Although the pathophysiology of EDS is increasingly understood, the psychosocial effects of having EDS have not been examined. We psychologically tested and interviewed 41 adults and 7 children with EDS. Anxiety, depression, anger, and interpersonal concerns were significantly elevated, varying from one-quarter to one-third of patients; over 70% had a history of some mental health care use. Psychological difficulties appear to result from chronic pain and disability, ostracism or avoidance of relationships and social activities, sexual difficulties and reproductive concerns, and frustration with the medical system. Specific types of EDS (e.g., EDS Type I) are associated with greater pain and psychological distress. Psychological intervention, prescribed with the recognition that psychiatric features are secondary to EDS, is recommended for some patients.

Ehlers-Danlos syndromes: revised nosology, Villefranche, 1997. Ehlers-Danlos National Foundation (USA) and Ehlers-Danlos Support Group (UK).

Categorization of the Ehlers-Danlos syndromes began in the late 1960s and was formalized in the Berlin nosology. Over time, it became apparent that the diagnostic criteria established and published in 1988 did not discriminate adequately between the different types of Ehlers-Danlos syndromes or between Ehlers-Danlos syndromes and other phenotypically related conditions. In addition, elucidation of the molecular basis of several Ehlers-Danlos syndromes has added a new dimension to the characterization of this group of disorders. We propose a revision of the classification of the Ehlers-Danlos syndromes based primarily on the cause of each type. Major and minor diagnostic criteria have been defined for each type and complemented whenever possible with laboratory findings. This simplified classification will facilitate an accurate diagnosis of the Ehlers-Danlos syndromes and contribute to the delineation of phenotypically related disorders.

Spondyloepiphyseal dysplasia, mild autosomal dominant type is not due to primary defects of type II collagen.

A mild autosomal dominant form of spondyloepiphyseal dysplasia (SED) is present in several generations of a South African family of English stock. This phenotype differs from that of any other previously described. Although type II collagen defects have been found in some families with SED congenita, the phenotype in our family showed discordant segregation with COL2A1 gene associated restriction fragment length polymorphisms (RFLPs), the markers for the structural locus of type II collagen. It is evident that the SED group of disorders is heterogeneous.

Grebe syndrome: clinical and radiographic findings in affected individuals and heterozygous carriers.

Grebe syndrome is a recessively inherited acromesomelic dysplasia. We studied, clinically and radiographically, 10 affected individuals, originating from Bahia, Brazil. The phenotype is characterized by a normal axial skeleton and severely shortened and deformed limbs, with a proximo-distal gradient of severity. The humeri and femora were relatively normal, the radii/ulnae and tibiae/fibulae were short and deformed, carpal and tarsal bones were fused, and several metacarpal and metatarsal bones were absent. The proximal and middle phalanges of the fingers and toes were invariably absent, while the distal phalanges were present. Postaxial polydactyly was found in several affected individuals. Several joints of the carpus, tarsus, hand, and foot were absent. Heterozygotes presented with a variety of skeletal manifestations including polydactyly, brachydactyly, hallux valgus, and metatarsus adductus. Grebe syndrome is caused by a missense mutation in the gene encoding cartilage-derived morphogenetic protein-1.

A split hand-split foot (SHFM3) gene is located at 10q24-->25.

The split hand-split foot (SHSF) malformation affects the central rays of the upper and lower limbs. It presents either as an isolated defect or in association with other skeletal or non-skeletal abnormalities. An autosomal SHSF locus (SHFM1) was previously mapped to 7q22.1. We report the mapping of a second autosomal SHSF locus to 10q24-->25. A panel of families was tested with 17 marker loci mapped to the 10q24-->25 region. Maximum lod scores of 3.73, 4.33 and 4.33 at a recombination fraction of zero were obtained for the loci D10S198, PAX2 and D10S1239, respectively. An 19 cM critical region could be defined by haplotype analysis and several genes with a potential role in limb morphogenesis are located in this region. Heterogeneity testing indicates the existence of at least one additional autosomal SHSF locus.

Novel approach to the molecular diagnosis of Marfan syndrome: application to sporadic cases and in prenatal diagnosis.

Marfan syndrome is an autosomal dominant disorder affecting the skeletal, ocular, and cardiovascular systems. Defects in the gene that encodes fibrillin-1 (FBN1), the main structural component of the elastin-associated microfibrils, are responsible for the disorder. Molecular diagnosis in families with Marfan syndrome can be undertaken by using intragenic FBN1 gene markers to identify and track the disease allele. However, in sporadic cases, which constitute up to 30% of the total, DNA-based diagnosis cannot be performed using linked markers but rather requires the identification of the specific FBN1 gene mutation. Due to the size and complexity of the FBN1 gene, identification of a causative Marfan syndrome mutation is not a trivial undertaking. Herein, we describe a comprehensive approach to the molecular diagnosis of Marfan syndrome that relies on the direct analysis of the FBN1 gene at the cDNA level and detects both coding sequence mutations and those leading to exon-skipping, which are often missed by analysis at the genomic DNA level. The ability to consistently determine the specific FBN1 gene mutation responsible for a particular case of Marfan syndrome allows both prenatal and pre-implantation diagnosis, even in sporadic instances of the disease.

Chronic pain is a manifestation of the Ehlers-Danlos syndrome.

The Ehlers-Danlos syndrome (EDS) is a group of heritable systemic disorders of connective tissue manifesting joint hypermobility, skin extensibility, and tissue fragility. Although the presence of pain has been documented in the various types of the EDS, its natural history, distribution, and management have not been defined. We conducted a structured interview in 51 individuals affected with different types of EDS. Affected individuals reported chronic pain of early onset involving most frequently the shoulders, hands, and knees. Pain was generally refractory to a variety of pharmacologic and physical interventions. Chronic pain is a common manifestation of EDS.

The genetic basis of aortic disease. Marfan syndrome and beyond.

The Marfan syndrome and related disorders are systemic disorders of connective tissue. Proximal aorta is usually dilated. The molecular basis of Marfan syndrome has been elucidated, thus allowing prenatal diagnosis. Life expectancy has markedly improved due to the widespread use of beta-adrenergic receptor inhibitors and improved surgical management of the aortic disease.

Internal carotid artery aneurysm: a vascular manifestation of type IV Ehlers-Danlos syndrome.

Aneurysms of the distal internal carotid artery (ICA) can be difficult to manage. When seen in a patient with Ehlers-Danlos Syndrome, type IV (EDS-Type IV), the complexity of the problem is greatly increased. Proximal ICA ligation in the presence of an intact circle of Willis and adequate collateral circulation is a reasonable and safe approach. We recommend the liberal use of duplex scanning and intravenous digital angiography in patients with EDS, and plan to use these techniques to follow the small, asymptomatic, right ICA aneurysm in our patient. If the aneurysm rapidly grows or becomes symptomatic, treatment may require proximal ligation with extracranial-intracranial bypass. Understanding of the basic defects associated with EDS-Type IV will make the management of patients with vascular complications more safe.