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Biomedical subjects

M J Seller

Publications and source records attributed to M J Seller.

At least 19 recordsLinked to original sources
PubMed2001

Physical and transcript map of the dominant optic atrophy (OPA1) gene critical region at 3q28-q29.

The dominant optic atrophy gene (OPA1) has previously been mapped to chromosome 3q28-q29. We have now constructed a physical and transcriptional map across the OPA1 critical region between markers D3S3557 and D3S3346. It comprises 21 sequence-tagged sites (STSs), 4 single nucleotide polymorphisms, 29 expressed sequence tags, 2 known genes, and 12 newly generated STSs anchored onto 21 yeast artificial chromosome, 22 bacterial artificial chromosome, 48 P1 phage artificial chromosome, and 42 cosmid overlapping clones spanning 2.5 Mb. The map has allowed us to order many of the markers hitherto only roughly defined and to exclude 23 of the putative candidate genes assigned to the region. We found the OPA1 critical interval to be 450-550 kb. It contains 2 known genes, RPL35a and SDHA, which thus constitute candidate genes.

Chromosomes, Human, Pair 3↗
PubMed2001

A 46,XX fetus with external female and internal male genitalia, facial dysmorphic features and mildly dilated lateral ventricles of the brain: a new syndrome?

The clinical features of a 46,XX fetus with dysmorphic facial features, mild dilatation of the lateral ventricles of the brain, and female external and male internal genitalia are described. This combination of abnormalities does not appear to have been reported previously, and may represent a new syndrome.

Abnormalities, Multiple↗
PubMed1999

Genomic cloning and characterization of the human homeobox gene SIX6 reveals a cluster of SIX genes in chromosome 14 and associates SIX6 hemizygosity with bilateral anophthalmia and pituitary anomalies.

The Drosophila gene sine oculis (so), a nuclear homeoprotein that is required for eye development, has several homologues in vertebrates (the SIX gene family). Among them, SIX3 is considered to be the functional orthologue of so because it is strongly expressed in the developing eye. However, embryonic SIX3 expression is not limited to the eye field, and SIX3 has been found to be mutated in some patients with holoprosencephaly type 2 (HPE2), suggesting that SIX3 has wide implications in head development. We report here the cloning and characterization of SIX6, a novel human SIX gene that is the homologue of the chick Six6(Optx2) gene. SIX6 is closely related to SIX3 and is expressed in the developing and adult human retina. Data from chick and mouse suggest that the human SIX6 gene is also expressed in the hypothalamic and the pituitary regions. SIX6 spans 2567 bp of genomic DNA and is split in two exons that are transcribed into a 1393-nucleotide-long mRNA. Chromosomal mapping of SIX6 revealed that it is closely linked to SIX1 and SIX4 in human chromosome 14q22.3-q23, which provides clues about the origin and evolution of the vertebrate SIX family. Recently three independent reports have associated interstitial deletions at 14q22.3-q23 with bilateral anophthalmia and pituitary anomalies. Genomic analyses of one of these cases demonstrated SIX6 hemizygosity, strongly suggesting that SIX6 haploinsufficiency is responsible for these developmental disorders.

Amino Acid Sequence↗
PubMed1999

Dominant optic atrophy. Refining the clinical diagnostic criteria in light of genetic linkage studies.

OBJECTIVE: To describe the clinical findings and refine the clinical diagnostic criteria for dominant optic atrophy based on eight British families in which the diagnosis was confirmed by linkage analysis. DESIGN AND PARTICIPANTS: Case series; 92 subjects in 8 pedigrees had both eyes examined. INTERVENTION: Family members received a domiciliary examination based on best-corrected visual acuity, color vision using Ishihara and Hardy Richter Rand (HRR) plates, confrontation field testing using a red target, and optic disc evaluation using a direct ophthalmoscope. Genomic DNA was extracted from leukocytes or buccal mucosal cells and genotyped using 12 fluorescently labeled microsatellite markers from the region 3q27-q29. MAIN OUTCOME MEASURES: Subjects were classified clinically as definitely or possibly affected on the basis of the domiciliary examination before genetic analysis, and these results were compared with the haplotype analysis. RESULTS: Clinically, 43 subjects were identified as definitely affected, 4 as possibly affected, and 45 as unaffected. Visual acuity in affected subjects ranged from 6/6 to count fingers and declined with age. On genetic analysis, a haplotype was identified in each family, which was found in all definitely affected members but not in those regarded as unaffected. The four possibly affected individuals also bore the haplotype that segregated with the disease. CONCLUSIONS: Simple clinical tests are highly efficacious in diagnosing dominant optic atrophy. Contrary to accepted criteria, symptoms begin before the age of 10 years in only 58% of affected individuals. Visual acuity in affected subjects is highly variable. A mild degree of temporal or diffuse pallor of the optic disc and minimal color vision defects, in the context of a family with dominant optic atrophy, are highly suggestive of an individual being affected, even if the visual acuity is normal. This widens the generally accepted diagnostic criteria for this disease.

Adolescent↗
PubMed1998

Altered smooth muscle development and innervation in the lower genitourinary and gastrointestinal tract of the male human fetus with myelomeningocele.

PURPOSE: We determine whether smooth and skeletal muscle or nerve density is altered in the lower genitourinary or gastrointestinal tract of male human fetuses with myelomeningocele at 20 weeks of gestation. MATERIALS AND METHODS: We serially cross sectioned the lower genitourinary and gastrointestinal tracts in 7 male fetuses (mean age 20 weeks of gestation) with myelomeningocele and 4 age matched controls. Immunohistochemical staining was performed using Masson's trichrome stain and antibodies to smooth and skeletal muscle actin. S-100 protein staining for Schwann cell localization and neurofilament protein was also done. Fluorescein and rhodamine double immunolabeling was used to demonstrate the co-expression of smooth and skeletal muscle. RESULTS: Peripheral neural innervation of the bladder, prostate and rectum was markedly decreased in myelomeningocele. Masson's trichrome and smooth muscle actin staining also demonstrated that smooth muscle was less well differentiated in myelomeningocele specimens. Scant smooth muscle was present in the myelomeningocele bladder and bladder neck with an excess of collagen in an interfascicular and intrafascicular distribution. Double immunofluorescence staining revealed persistent co-expression of smooth and skeletal muscle actin by myocytes in the myelomeningocele detrusor, while in the control bladder there was only smooth muscle expression. The skeletal muscle component of structures in fetuses with myelomeningocele, including the external sphincter, was similar to that in controls. Prostatic size, ductal morphogenesis and smooth muscle were decreased compared to those in controls. CONCLUSIONS: A global defect exists in the development of smooth muscle in myelomeningocele in the lower genitourinary and gastrointestinal tracts by 20 weeks of gestation. Peripheral nerve density is decreased in smooth muscle in myelomeningocele, suggesting that an intact nervous system is important for the development of normal smooth muscle. Fetal surgery with coverage of the spinal cord in select cases may prevent progressive environmental injury to the somatic nervous system during the second half of gestation. However, achieving normal autonomic function is unlikely due to the extent of early global organ maldevelopment.

Digestive System↗
PubMed1998

Trisomy 9 in an embryo with spina bifida.

The products of a 14 week spontaneous abortion were examined and found to contain an embryo at a developmental age of around 35 days. It had a cystic lumbosacral spina bifida and was trisomic for chromosome 9.

Abortion, Spontaneous↗
PubMed1998

Cerebellar hypoplasia, facial dysmorphism and internal abnormalities: a new recessive syndrome?

Three female sibs had cerebellar hypoplasia, facial dysmorphism comprising a high forehead, lowset posteriorly rotated ears, a prominent upper lip and receding chin, and variable internal abnormalities. Two of the cases had deficient lobulation of the lungs, two had an atrial septal defect of the heart and developmental abnormalities of the urinary system or internal genitalia, one had holoprosencephaly. All had normal chromosomes. This syndrome does not seem to have been reported before and may be inherited in an autosomal recessive manner.

Abnormalities, Multiple↗
PubMed1997

Dominant optic atrophy, Kjer type. Linkage analysis and clinical features in a large British pedigree.

OBJECTIVES: To perform DNA linkage studies in an extensive 5-generation British pedigree with dominant optic atrophy and to validate the efficacy of domiciliary screening for affected members. METHODS: Family members received a domiciliary examination based on corrected visual acuity, color vision, visual field defects, and optic disc appearance; DNA linkage analysis was performed using 7 microsatellite markers on 3q27-qter. RESULTS: Based on the results of the ophthalmic examination, 15 members could be classified as definitely affected, 1 probably affected, and 25 unaffected. Two-point linkage analysis gave significant maximum lod scores at theta [corrected] = 0.00, with the markers D3S3669, D3S3590, and D3S3642. A haplotype segregating with the disease was identified in affected individuals, including the probably affected subject. Informative meioses defined the disease interval between markers D3S1601 and D3S1265. CONCLUSIONS: Domiciliary screening was effective in identifying all 16 affected members of a British family with dominant optic atrophy. The typical clinical features were present. The location of the OPA1 gene in this new British family seems to be in the 3q27-28 region and is the same as that reported in Danish, Cuban, and French families, suggesting no genetic heterogeneity in this disorder.

Adult↗
PubMed1997

The spinal cord lesion in human fetuses with myelomeningocele: implications for fetal surgery.

Recently produced experimental evidence suggests that secondary traumatic injury and degenerative changes, acquired in utero, to the openly exposed neural tissue may be primarily responsible for the massive neurological deficit associated with myelomeningocele (MMC). The goal of this study was to examine the morphology of human fetuses with MMC to determine if acquired trauma to the spinal cord could be identified. The MMC lesions with surrounding tissues from 10 human fetuses ranging in gestational age between 19 and 23 weeks were prepared with serial histological sections. The MMC lesions were characterized by an open vertebral arch, an open dura mater fused laterally to the dermis, and an open pia mater fused laterally to the epidermis. The spinal cord was exposed, without any meningeal, bony, or cutaneous covering, and was resting on the dorsal aspect of the abnormal arachnoid sac created by the fusion of the meninges to the cutaneous tissues. The exposed neural tissue had undergone varying degrees of recent traumatic injury as a result of its exposed position, ranging from nearly complete preservation of neural elements in four cases to nearly complete loss in two cases. The neural tissue remaining in the MMC with partial loss contained hemorrhages and abrasions from recent injury, suggesting that injury occurred during passage through the birth canal. The presence of dorsal and ventral parts of the cord with nerve roots and ganglia demonstrated that these structures had formed during development and that the loss of tissue by injury was a secondary change. The results support the concept that performing in utero surgery could protect the exposed but initially well-developed and uninjured cord, prevent secondary neural injury, and preserve neural function in the human fetus with myelomeningocele.

Brain Damage, Chronic↗
PubMed1997

Rapid identification of multiple supernumerary ring chromosomes with a new FISH technique.

Multiple supernumerary ring chromosomes are a rare cytogenetic finding which is poorly understood. With the introduction of FISH techniques, their chromosomal origin can now be defined clearly. The techniques described previously are complicated and time consuming. We report a new rapid technique which has been used to investigate two new cases. Multiple probes were hybridised to a single slide by means of marking the underside with a diamond pen to form a grid of squares, pipetting fixed cell suspension into the centre of each square, forming a rubber solution grid on the denatured, dehydrated slide following the lines on the underside, adding a mixture of probes into each square, and sealing the slide with a silicone rubber rim and a covering slide. The type of probe and the size, dimensions, and number of squares in the grid can be tailored to individual cases. The two new cases examined here are mosaic for three (case 1) and four (case 2) supernumerary ring chromosomes derived from different chromosomes. Normal cell lines were also present. The karyotypes were established as 47,XY,+r(4)/47,XY,+r(17)/.../48,XY,+r(17),+r(20)/ 49,XY,+r(4),+r(17),+r(20)/46,XY for case 1 and 47,XX,+r(4)/47,XX,+r(8)/47,XX,+r (10)/48,XX,+r(X),+r(4)/... /49,XX,+r(X),+r (8),+r(10)/46,XX for case 2. Our findings suggest that the ring chromosomes were formed during meiosis, perhaps involving complex rearrangements, resulting in a germ cell containing all markers, with subsequent loss of markers during cell division. Our second case also shows that the outcome is not invariably mental or physical handicap.

Child, Preschool↗
PubMed1997

Linkage studies in dominant optic atrophy, Kjer type: possible evidence for heterogeneity.

Dominant optic atrophy, Kjer type, is an autosomal dominant disorder causing progressive loss of visual acuity and colour vision from early childhood. The gene (OPA1) has variable expressivity, a penetrance of 0.98, and the locus has been localised to 3q28-29. We have genotyped nine British families with the disease using 12 polymorphic microsatellite markers from this region. Linkage and haplotype analysis shows the OPA1 gene to be located in a 2.3 cM interval between markers D3S1601 and D3S2748. One family showed no evidence of linkage with the chromosome 3 markers, suggesting for the first time that locus heterogeneity for this disease may exist, although exclusion for linkage is based on unaffected subjects. In addition, analysis of recombinants has enabled us to order the 12 markers along chromosome 3.

Adolescent↗
PubMed1997

Phenotypic diversity in the Smith-Lemli-Opitz syndrome.

The phenotype of four cases of Smith-Lemli-Opitz syndrome (SLO) with proven defects in cholesterol biosynthesis are compared, and shown to be markedly disparate even between sibs, and demonstrate the dilemma for the clinician. The advent of a biochemical test for SLO has been enormously valuable in determining which patients are truly affected by the condition, but because of the wide phenotypic variation, a diagnosis on clinical features alone remains problematic.

Abnormalities, Multiple↗
PubMed1996

Evolution of sonographic findings in a fetus with agenesis of the urethra, vagina, and rectum.

In a 12-week gestation fetus, routine ultrasound examination suggested dilated loops of bowel. Repeat scans at 13 and 15 weeks showed normal growth but persistence of bowel dilatation. At 20 weeks there was megacystis, hyperechogenic bowel, ascites, and oligohydramnios. The diagnosis of cloacal abnormality was suspected and the parents chose to have pregnancy termination. Post-mortem examination demonstrated female pseudohermaphroditism with agenesis of the urethra, vagina, and rectum.

Adolescent↗
PubMed1996

Esophageal and duodenal atresia in a fetus with Down's syndrome: prenatal sonographic features.

Ultrasound examination of a 22-week fetus demonstrated a grossly distended stomach and proximal duodenum, with a large cystic area in the chest. There was associated polyhydramnios. A presumptive diagnosis of duodenal atresia with a congenital diaphragmatic hernia was made. Analysis of a fetal blood sample showed that the fetus had Down's syndrome. Histological examination after termination of the pregnancy revealed the unusual combination of duodenal and esophageal atresia, with an intact diaphragm.

Adult↗
PubMed1996

A new lethal chondrodysplasia with platyspondyly, long bone angulation and mixed bone density.

A fetus diagnosed by sonography at 20 weeks' gestation had multiple skeletal abnormalities. The main features were absent ossification of the skull and cervical and upper thoracic vertebral bodies; short, angulated femora, tibiae, radii and ulnae but normal humeri; platyspondyly; trident-shaped acetabular roofs; sclerotic bands on the iliac wings and scapulae; clavicular hooks; and overall, mixed bone density. We suggest that this is a new chondrodysplasia which, since the parents are first cousins, could follow autosomal recessive inheritance.

Abnormalities, Multiple↗