[Show abstract][Hide abstract] ABSTRACT: To illustrate the use of bacterial artificial chromosome (BAC) clone panels for molecular cytogenetic analysis of complex chromosome rearrangements (CCRs).
High resolution cytogenetics followed by fluorescence in situ hybridization (FISH) analysis using chromosome band-specific BAC probes, in addition to commercially available probes.
High resolution cytogenetics in conjunction with FISH using commercially available probes proved inadequate to resolve problems in characterizing a balanced CCR in the mother of a patient who had inherited an unbalanced form of the CCR. Accurate interpretation of the CCR and the unbalanced rearrangement in the patient as trisomy 7p12.2-->p21.3 was accomplished only through use of the BAC clone panel.
Use of BAC clone panels can enhance the power of FISH analysis in defining chromosome rearrangements that cannot be resolved by high resolution chromosome analysis.
Genetics in Medicine 01/2001; 3(2):126-31. · 5.56 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We report the case of a boy with achondroplasia and i(21q) Down syndrome. Besides craniofacial features typical in Down syndrome, the skeletal findings of achondroplasia dominate the clinical picture. The diagnosis of Down syndrome was based on clinical features and the cytogenetic finding of i(21q) trisomy 21. The diagnosis of achondroplasia was based on the presence of clinical and radiographic findings and confirmed by the presence of a common FGFR3 gene mutation (Gly380Arg) detected by restriction enzyme analysis and sequencing of the polymerase chain reaction products. This is the first report of achondroplasia associated with i(21q) Down syndrome.
Southern Medical Journal 07/2000; 93(6):622-4. · 0.92 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Ehlers-Danlos syndrome (EDS) type VIIC is a recessively inherited connective-tissue disorder, characterized by extreme skin fragility, characteristic facies, joint laxity, droopy skin, umbilical hernia, and blue sclera. Like the animal model dermatosparaxis, EDS type VIIC results from the absence of activity of procollagen I N-proteinase (pNPI), the enzyme that excises the N-propeptide of type I and type II procollagens. The pNPI enzyme is a metalloproteinase containing properdin repeats and a cysteine-rich domain with similarities to the disintegrin domain of reprolysins. We used bovine cDNA to isolate human pNPI. The human enzyme exists in two forms: a long version similar to the bovine enzyme and a short version that contains the Zn++-binding catalytic site but lacks the entire C-terminal domain in which the properdin repeats are located. We have identified the mutations that cause EDS type VIIC in the six known affected human individuals and also in one strain of dermatosparactic calf. Five of the individuals with EDS type VIIC were homozygous for a C-->T transition that results in a premature termination codon, Q225X. Four of these five patients were homozygous at three downstream polymorphic sites. The sixth patient was homozygous for a different transition that results in a premature termination codon, W795X. In the dermatosparactic calf, the mutation is a 17-bp deletion that changes the reading frame of the message. These data provide direct evidence that EDS type VIIC and dermatosparaxis result from mutations in the pNPI gene.
The American Journal of Human Genetics 08/1999; 65(2):308-17. · 11.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We report on two sibs with a paracentric inversion of chromosome 1 [inv(1)(p22.3p34.1)] and a small deletion of the same chromosome (p34.1-->p34.3). They presented with learning disabilities and disturbed conduct but lacked the more severe manifestations usually associated with autosomal chromosome deletion. Born to an alcoholic mother and later placed in foster care because of abuse and neglect, the behavior abnormalities they present are likely to be associated with their traumatic postnatal experience. Microscopic deletions without significant morphological phenotypic expression have been described but are rarely reported. Most reported cases of interstitial deletion of 1p had associated malformations and psychomotor retardation. These sibs may represent the first evidence that deletion of 1p34.1-->1p34.3 may have little impact on the phenotype.
American Journal of Medical Genetics 02/1999; 82(2):107-9.
[Show abstract][Hide abstract] ABSTRACT: We present a patient with developmental delay, minor anomalies, and duplication 18p confirmed by fluorescence in situ hybridization with whole chromosome 18 painting probe (Oncor p5218). Our observation confirms the findings of other investigators that duplication 18p is not associated with major malformations.
American Journal of Medical Genetics 01/1999; 80(5):487-90.
[Show abstract][Hide abstract] ABSTRACT: Intrachromosomal rearrangements usually result from three of fewer breaks. We report a complex intrachromosomal rearrangement resulting from five breaks in one chromosome 10 of a phenotypically normal father of two developmentally delayed children. GTG-banding analysis of the father's rearranged chromosome 10 suggested in initial pericentric inversion followed by an insertion from the short arm into the terminal band of the long arm [der(10) (pter-->p13::q21.2-->p12.2::q22.1::-->q26.3::q22.1-->q 21.2::p12.2-->p13::q26.3-->qter)]. To our knowledge, this rearrangement is the most complex ever reported in a single chromosome. Both children inherited a recombinant chromosome 10 with loss of the insertion and the segment distal to it [rec(10)der(pter-->p13: :q21.2-->p12.2::q22.1-->q26.3:)]. Mechanisms for both rearrangements are proposed.
American Journal of Medical Genetics 05/1996; 63(2):392-5.
[Show abstract][Hide abstract] ABSTRACT: The telomeres of gorilla, chimpanzee and human peripheral blood cells have been examined by hybridization to an oligonucleotide probe, (TTAGGG)4, following conventional and pulsed-field electrophoresis procedures. The MspI site present near the chromosome terminus undergoes methylation in gorilla, chimpanzee and human genome as shown by the HpaII digestion. Minor (TTAGGG)4-hybridizing sequences have been also detected in the chimpanzee HindIII and MspI digests.
Biochemistry and molecular biology international 10/1995; 37(1):57-64.
[Show abstract][Hide abstract] ABSTRACT: Damage to mitochondrial DNA (mtDNA) has recently been associated with a variety of human diseases including cancer, diabetes mellitus, and aging. The mechanisms by which the mitochondria respond to DNA damage are of prime importance in understanding how damage can persist and cause disease. Here we demonstrate the repair of mitochondrial DNA damage induced by the naturally occurring, radiomimetic drug bleomycin. WI-38 cells were first permeabilized using 20 micrograms/ml lysophosphatidylcholine in order to increase the intracellular concentration of bleomycin. Dose response studies with the permeabilized cells showed that a concentration of 5 micrograms/ml bleomycin given for 30 min caused sufficient DNA damage for repair studies. Following treatment with this concentration of bleomycin, repair of mtDNA damage was found to be about 80% by 2 h. However, after 4 h no additional repair was observed. The results indicate that there is an efficient DNA repair system in human mitochondria for some types of damage caused by bleomycin. However, there is a component of damage caused by this agent that either is not repaired or is removed at a much slower rate.
Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 08/1995; 337(1):19-23. · 3.90 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Dicentrics are among the most common structural abnormalities of the human Y chromosome. Predicting the phenotypic consequences of different duplications and deletions of dicentric Y chromosomes is usually complicated by varying degrees of mosaicism (45,X cell lines), which may, in some cases, remain undetected. Molecular studies in patients with dicentric Y chromosomes have been few, and only two studies have attempted to determine the presence of SRY (the putative testis-determining factor gene). We report an 18-year-old female with short stature, amenorrhea, hirsutism, hypoplastic labia minora, and clitoromegaly who has a 45,X/46,X,idic(Y)(p11.32)/47,X,idic(Y)(p11.32),idic(Y) (p11.32) karyotype. Southern analysis using Y-specific probes (Y97, 2D6, 1F5, pY3.4) and polymerase chain reaction (PCR) analysis using primers for ZFY and SRY were positive for all loci tested, indicating that almost all of the Y chromosome was present. Our findings and an extensive review of the literature emphasize the importance of molecular analyses of abnormal Y chromosomes before any general conclusions can be reached concerning the relative effects of the Y-chromosome abnormality and mosaicism on sexual differentiation.
Human Genetics 08/1995; 96(1):119-29. · 4.63 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Two newborn infants with fetal akinesia sequence were noted to have multiple perinatal fractures of the long bones. The radiographic manifestations are characterized by gracile ribs, thin long bones, and multiple diaphyseal fractures. Consistent histopathologic changes of bone are irregular with focal areas of extreme diaphyseal thinning, thin and long marrow spicules, and with or without callous formation at fracture sites. Pathogenic mechanisms of bone fractures in fetal akinesia sequence and the differential diagnoses of congenital/perinatal bone fractures are discussed.
American Journal of Medical Genetics 03/1995; 55(4):472-7.
[Show abstract][Hide abstract] ABSTRACT: We describe a method for rapid and efficient polymerase chain reaction (PCR) amplification of specific target DNA sequences directly from cells fixed in 3:1 methanol-acetic acid (Carnoy's fixative) for routine cytogenetic analysis. The fixed cells used had been stored at -20 degrees C from a few weeks up to 6 years. Primer sets used correspond to loci on an autosome (retinoblastoma, RB1), as well as the X (Duchenne muscular dystrophy, DMD) and Y (sex-determining region of the Y, SRY) chromosomes. Sizes of amplified products were the expected 400, 251 and 609 bps, respectively. No differences in quality of amplification products were found between PCR templates obtained from fresh tissues or from cells fixed for varying lengths of time in Carnoy's fixative. This technique has the following advantages: (1) it allows retrospective studies of genetic disorders from archived specimens; (2) it requires only a limited number of cells; (3) it is rapid and simple; and (4) it avoids multistep procedures required in extraction of the DNA.
American Journal of Medical Genetics 02/1995; 55(1):116-9.
[Show abstract][Hide abstract] ABSTRACT: Advances in medical genetics, including mapping of human genome, improved therapy for genetic disorders, and new screening tests for carrier detection and prenatal diagnosis, have created a growing demand for clinical genetic services in the United States. Such services (diagnosis, management, and genetic counseling) received support from state, federal, and private sources and were mostly based in academic medical centers. Gradually, such programs evolved into regional or state-wide activities with an emphasis on outreach clinics. Now, an increasing number of for-profit corporations have entered into this field. Clinical genetic teams usually include clinical geneticists and other professionals with expertise in the diagnosis and management of genetic conditions and skills in information presentation and family support. The American Board of Medical Genetics, the newest member of the American Board of Medical Specialties, provides certification for five categories of genetics professionals and sets standards for training programs. Based on personal experiences from the states of Alabama and Ohio and data from the Council of Regional Networks for Genetic Services, we show and compare trends of newborn screening programs and regional genetic services. The effects of economic and social trends as they impinge on genetic services are monitored via several databases in our center.
The Japanese journal of human genetics 07/1994; 39(2):275-88.
[Show abstract][Hide abstract] ABSTRACT: We report on a boy with excessively wrinkled skin, mild micro/brachycephaly with mild hydrocephalus and slightly small temporal lobes, apparently low-set ears, retro/micrognathia and cleft soft palate (Pierre-Robin anomaly), patent ductus arteriosus and foramen ovale, pulmonary hypoplasia, eventration of the left hemidiaphragm, right cryptorchidism, a sacral dimple, flexion contractures of fingers and knees, and equinovarus deformities of both feet. The infant had a de novo dir dup(1)(pter-->q25::q12-->qter). Partial duplications involving proximal 1q have rarely been reported. Furthermore, this is the first case of proximal duplication of chromosome 1q with unequivocal identification using fluorescence in situ hybridization (FISH) with a chromosome 1 painting probe.
American Journal of Medical Genetics 03/1994; 50(1):28-31.
[Show abstract][Hide abstract] ABSTRACT: We describe a mother and daughter with typical cri du chat syndrome. Previous investigators have noted the lack of information about the reproductive fitness of patients with this disorder. This report demonstrates that females with cri du chat syndrome are fertile, can gestate and likewise deliver affected offspring, which has significant management and counseling implications.
[Show abstract][Hide abstract] ABSTRACT: An 11-year-old girl with short stature, mental retardation, and mild dysmorphic features was found to have an inverted duplication of most of the short arm of the X chromosome [dic inv dup(X)(qter-->p22.3::p22.3-->cen:)]. Her mother, who is also short and retarded, carries the same duplication. Fluorescence in situ hybridization with an X chromosome library, and with X centromere-specific alpha satellite and telomere probes, was useful in characterizing the duplication. In most females with structurally abnormal X chromosomes, the abnormal chromosome is inactivated. Although the duplicated X was consistently late replicating in the mother, X chromosome inactivation studies in the proband indicated that in 11% of her lymphocytes the duplicated X was active.
Human Genetics 05/1993; 91(4):395-400. · 4.63 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We describe initial observations of an infant with dermatosparaxis (another form of Ehlers-Danlos syndrome, designated as type VIIC), an autosomal recessive disorder characterized by skin fragility and described in several species of domesticated animals. Electron microscopic examination of the skin shows collagen sheets rather than fibrils, and characteristic distortions resembling hieroglyphs. In addition to skin fragility, the disorder is characterized by redundant skin folds and edema, healing with minimal scar formation, large fontanels and wide sagittal and metopic sutures, blue sclerae, micrognathia, and umbilical hernia; after the neonatal period there are joint laxity, growth failure, short limbs, and normal mineralization of the skeleton except for the cranial vault. This disorder may also be a cause of premature rupture of placental membranes and myopia.
Journal of Pediatrics 11/1992; 121(4):558-64. · 4.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Dermatosparaxis is a recessively inherited connective-tissue disorder that results from lack of the activity of type I procollagen N-proteinase, the enzyme that removes the amino-terminal propeptides from type I procollagen. Initially identified in cattle more than 20 years ago, the disorder was subsequently characterized in sheep, cats, and dogs. Affected animals have fragile skin, lax joints, and often die prematurely because of sepsis following avulsion of portions of skin. We recently identified two children with soft, lax, and fragile skin, which, when examined by transmission electron microscopy, contained the twisted, ribbon-like collagen fibrils characteristic of dermatosparaxis. Skin extracts from one child contained collagen precursors with amino-terminal extensions. Cultured fibroblasts from both children failed to cleave the amino-terminal propeptides from the pro alpha 1(I) and pro alpha 2(I) chains in type I procollagen molecules. Extracts of normal cells cleaved to collagen, the type I procollagen synthesized by cells from both children, demonstrating that the enzyme, not the substrate, was defective. These findings distinguish dermatosparaxis from Ehlers-Danlos syndrome type VII, which results from substrate mutations that prevent proteolytic processing of type I procollagen molecules.
The American Journal of Human Genetics 09/1992; 51(2):235-44. · 11.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Neurofibromatosis 2 or bilateral acoustic neurofibromatosis (NF2) is a severe autosomal dominant disorder characterized by the development of multiple tumors of the nervous system, including meningiomas, gliomas, neurofibromas, ependymomas, and particularly acoustic neuromas. Polymorphic DNA markers have revealed frequent loss of one copy of chromosome 22 in the tumor types associated with NF2. Family studies have demonstrated that the primary defect in NF2 is linked to DNA markers on chromosome 22, suggesting that it involves inactivation of a tumor suppressor gene. We have employed a combination of multipoint linkage analysis and examination of deletions in primary tumor specimens to precisely map the NF2 locus between flanking polymorphic DNA markers on chromosome 22. The 13-cM region bracketed by these markers corresponds to 13% of the genetic length of the long arm of chromosome 22 and is expected to contain less than 5 x 10(6) bp of DNA. The delineation of flanking markers for NF2 should permit accurate presymptomatic and prenatal diagnosis for the disorder and greatly facilitate efforts to isolate the defective gene on the basis of its location.
The American Journal of Human Genetics 03/1990; 46(2):323-8. · 11.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: At least eight provisional categories of neurofibromatosis have been proposed. Among these, neurofibromatosis 1 (von Recklinghausen's disease or peripheral neurofibromatosis) and neurofibromatosis 2 (central or bilateral acoustic neurofibromatosis) have been established as distinct disorders. We studied 15 affected male and 8 affected female members of one large kindred with neurofibromatosis 2. None of the patients met the diagnostic criteria for neurofibromatosis 1. Between the ages of 15 and 53 years, the patients had multiple central nervous system tumors of various types--mainly, bilateral acoustic neuromas. Two or more tumors eventually developed in 20 of the patients; 9 had evidence of only bilateral acoustic neuromas. Meningiomas and ependymomas were more common among the young patients; those who initially presented with acoustic neuromas were nearly a decade older. Intracranial nontumoral calcifications were present in most patients and were also found in symptom-free children. The presence of such lesions is probably a prodromic feature of neurofibromatosis 2. Simultaneous analysis of D22S1 and IGLV DNA markers for coinheritance with neurofibromatosis 2 indicates that the locus for the disease is near the center of the long arm of chromosome 22 (22q11.1----22q13.1). The eventual isolation of this disease gene may reveal a cause of the most common intracranial tumors in humans.
New England Journal of Medicine 09/1988; 319(5):278-83. · 54.42 Impact Factor