Thymidylate synthetase in mutants of Drosophila melanogaster.

Thymidylate synthetase has been examined with respect to the normal pattern of activity throughout the development of the Oregon-R strain of Drosophila melanogaster. Large amounts of the enzyme are present in both the unfertilized and the fertilized eggs. A comparison of the ovarian thymidylate synthetase activity of the Oregon-R strain and the female sterility mutants, fs(2)B, fu, and fs(1)N, indicates variations in the activity of this enzyme in each strain. At four days of age, the ovarian-specific activity of the female sterility mutants is comparable to or less than that of the Oregon-R strain, but it is reduced at fifteen days of age. The enzyme activity per ovary is low in the fs(2)B strain but is similar in the Oregon-R, fu, and fs(1)N strains. When expressed as activity per organism, thymidylate synthetase declines after six to eight hours of development until the minimal level is reached in the late embryonic stage. Enzyme activity rises throughout the larval instars, reaching a maximum immediately after puparium formation. The activity decreases during pupation, but rises again during the first four days of adult life.

Chromosome variants in children with psychiatric disorders.

The authors studied the frequency of chromosome variants in 48 hospitalized children with psychiatric diagnoses (study group) in comparison with 10 hospitalized children with nonpsychiatric diagnoses (control group) and the results of three surveys of newborn children. They found that the frequency of variants in their study group was elevated in comparison with their control group and with the newborn surveys.

Visual field development in infants with stage 3 retinopathy of prematurity.

Binocular visual field development was measured in 11 infants who had stage 3 ROP in early infancy and in 11 infants without ROP, matched for birthweight and gestational age. Kinetic perimetry was used to measure visual fields along the 45 degree, 135 degree, 225 degree and 315 degree half-meridia. Infants were tested at 4, 9, and 18 months from due date. Analyses of variance were used to compare results of the two groups for each age tested. Results at the 4-month test age indicated that both groups had visual fields within the normal range for their age. However, at the 9-month test age the ROP group showed a significantly (P less than 0.05) smaller visual field than the control group. At 18 months, the ROP group still showed smaller visual fields than the control group, but the difference was not significant. The results suggest that dysfunction of the peripheral retina associated with ROP may produce a constriction of the visual field or a delay in visual field development.

DNA linkage analysis of 26 families with fragile X syndrome.

Linkage data using the markers F9 (factor IX), DXS105 (cX55.7), DXS98 (4D-8), DXS52 (St14), DXS15 (DX13), and DXS134 (cpX67) are presented from 26 pedigrees segregating with fragile X (fra[X]) syndrome. Cytogenetic and DNA data were combined in 2-point linkage analysis for the estimation of lod scores and carrier probabilities in potential carriers. Recombination fractions (theta) corresponding to the maximum lod scores (Z) were obtained for F9 (Z = 2.78, theta = 0.15), DXS105 (Z = 1.72, theta = 14), DXS98 (Z = 3.74, theta = 0.00), DXS52 (Z = 3.53, theta = 0.17), DXS15 (Z = 4.03, theta = 0.11), and DXS134 (Z = 2.12, theta = 0.16) and for the fragile X locus (FRAXA). Recombination fractions between marker loci in the families are also presented. Discordance between the results of cytogenetic and DNA analyses in 2 potential carrier females was investigated by reexamination of the fragile site expression and was concluded to be due to the expression of the common fragile site at Xq27.2.

Unique X-linked mental retardation syndrome with fingertip arches and contractures linked to Xq21.31.

We studied 10 members of a 4 generation Missouri kindred with a dominant mental retardation syndrome with increasing severity in males. The 21 year-old propositus presented with severe mental retardation, microcephaly, asymmetric face, exotropia, hypogonadism, joint hypermobility, rocker bottom feet, and 10 low digital arches. Two brothers and a male cousin had similar features. The mother, sister, niece, maternal aunt, female cousin, and grandmother were examined and each had 8 to 10 low digital arches. Five of the women had exotropia and one had pes cavus feet. Chromosome analysis for fragile X in multiple relatives was normal. To determine the likelihood that this was an X-linked syndrome. DNA from relatives was hybridized to probes which detect 13 different loci spanning the X-chromosome. A peak LOD score of 2.78 at theta equal to 0.0 was calculated for the syndrome locus and DXYS1 (pDP34). The more distal Xq loci showed increasing recombination with the syndrome locus. These results are consistent with location for this syndrome near Xq21.31, the chromosomal locus for DXYSI.

New X-linked syndrome with seizures, acquired micrencephaly, and agenesis of the corpus callosum.

We report on 4 generations in a family with 3 living males, 3 males who died in infancy, and 3 females with neurologic impairment and agenesis of the corpus callosum (ACC). Manifestations in the surviving males include severe acquired micrencephaly, mental retardation, limb contractures, scoliosis, tapered digits with hyperconvex nails, a characteristic face with large eyes, prominent supraorbital ridges, synophris, optic atrophy, broad alveolar ridges and seizures. Urologic anomalies include renal dysplasia, cryptorchidism, and hypospadias. Two affected females were less severely impaired and continued to be socially responsive as adults, but had spastic quadriplegia and seizures. One obligate heterozygote was retarded with emotional problems while another obligate carrier female and her daughter were clinically normal. Pedigree analysis suggested X-linked inheritance with variable expression in females. These findings are inconsistent with the well-described X-linked conditions with ACC including FG syndrome and Aicairdi syndrome. ACC has not been described in Coffin-Lowry syndrome, a condition with similar clinical findings, which also demonstrates marked variability of expression in carrier females. In order to assist in carrier determination, brain imaging studies and DNA linkage analysis of the affected relatives was performed. We found a spectrum of agenesis of the corpus callosum with the most severe manifestations in the most severely affected males. DNA analysis using a series of X-linked probes suggests linkage with a LOD score of 1.26 at theta = 0 to a region between p 11.3 and p 21.3.

Pelizaeus-Merzbacher disease: clinical and DNA-linkage study of an extended family.

We describe a 5-generation family of 6 individuals with Pelizaeus-Merzbacher disease, Type I. DNA linkage study was done to establish carrier status. Two loci, DXS162 and DXYS1, were informative in this family for carrier determination. The highest lod score is that for PMD-DXYS1 (Z = 1.421 at theta = 0). The carrier probability can only be defined as likely or unlikely in the absence of an established recombination frequency.

Linkage and risk assessment in fragile X families using new DNA probes at Xq27.

Until recently few polymorphic loci had been genetically mapped close to the fragile X syndrome locus [FRAXA]. Six polymorphic loci, DXS369, DXS297, DXS296, DXS304, IDS and DXS374, have now been mapped closer to the fragile X FRAXA than in the present study. We report the results of genetic linkage analysis of 32 fragile X [fra(X)] families using 12 polymorphic loci including these new markers. Cytogenetic and molecular data were combined in two-point linkage analysis for the estimation of lod scores and carrier probabilities in potential carriers. Combined with results from previous studies, recombination fractions (0) corresponding to the maximum lod scores (Z max) were obtained for each of the 12 loci versus FRAXA. Recombination fractions between marker loci in the families were also calculated. The data were evaluated to determine the efficacy of using the strategy suggested by Suthers et al. (1991a) for molecular studies in fra(X) families. The large proportion of females heterozygous for at least one locus (83%) and of females heterozygous for flanking loci (60%) indicate that this is a very useful diagnostic strategy. Use of these new marker loci substantially changed the carrier risk estimates for members of 7 of the 32 families from the risk estimates previously calculated on the basis of less closely linked probes available prior to 1989.

X-linked mental retardation syndrome with characteristic "coarse" facial appearance, brachydactyly, and short stature maps to proximal Xq.

We describe a three-generation family in which X-linked mental retardation (XLMR) is associated with minor facial anomalies and brachydactyly. Two brothers and four nephews have "coarse" facial appearance, brachydactyly with widening of the distal phalanges, short stature, and moderate mental retardation. The three obligate carrier women have normal intelligence and normal physical findings. The results of linkage analysis carried out in 1988 using restriction fragment length polymorphisms (RFLPs) were suggestive of linkage to DXYS1 and DXS101 in proximal Xq (Zmax = 1.63 at straight thetamax = 0.0) [Carpenter et al., 1988: Am J Med Genet 43:A139]. The family was restudied with 16 microsatellite loci from Xp11.4 through Xq24. Linkage analysis demonstrated significant linkage to DXS1003, ALAS2, AR, DXS986, DXS990, DXS454, DXS1106, DXS1105, and DXS1220 from Xp11.3 to Xq23 (Zmax = 2.53 at straight thetamax = 0.0). Recombinations detected between MAOB and DXS1055 and between DXS1220 and DXS1001 place the disease locus between Xp11.3 and Xq23. Among the genes known to map to this region is the XNP gene for the alpha-thalassemia/mental retardation syndrome (ATR-X). This fact, along with the phenotypic similarity between our patients and ATR-X males, led us to consider XNP as a candidate gene for this family. X-inactivation studies provided further evidence for the involvement of XNP by showing completely skewed X-inactivation patterns in the three obligate carrier females, a pattern characteristic of carriers of XNP mutations.

Regional localization of a nonspecific X-linked mental retardation gene (MRX59) to Xp21.2-p22.2.

Linkage analysis was performed on a four-generation family with nonspecific mental retardation (MRX59). The five affected males, ranging in age from 2 years to 52 years, have a normal facial appearance and mild to severe mental impairment. Four obligate carriers are physically normal and not retarded. A maximum LOD score of 2.41 at straight theta = 0.00 was observed with the microsatellite markers, DMD45 in Xp21.2, DXS989 in Xp22.1, and DXS207 in Xp22.2. Recombinations were detected within the dystrophin gene (DMD) in one of the affected males and between DXS207 and DXS987 in Xp22.2 in one of the carriers. These recombinants define the proximal and distal boundaries of a candidate gene region. Genetic localization of this familial condition made prenatal diagnosis informative for one of the obligate carriers.

Martin-Bell syndrome segregating in a large kindred with normal transmitting males: clinical, cytogenetic, and linkage study.

We report on a large kindred with 10 mentally retarded, fra(X) positive males and 2 normal transmitting males. Clinical findings include variable degrees of facial anomalies, macroorchidism, behavioral characteristics, and cognitive deficiencies. The affected grandsons were fra(X) positive while their obligate carrier mothers and transmitting grandfathers were fra(X) negative. DNA-restriction fragment length polymorphism (RFLP) linkage study was undertaken to find informative markers to identify heterozygotes or hemizygotes. The problems encountered in genetic counselling, by the absence of established criteria for diagnosis, are discussed.

Linkage relationships between DXS105, DXS98, and other polymorphic DNA markers flanking the fragile X locus.

We report on linkage data between DXS105, DXS98, the locus for the fragile X syndrome (FRAXA), and 3 other polymorphic loci that flank the FRAXA locus. An analysis was undertaken to determine the relative positions of DXS105 and DXS98 and to test the assignment of DXS105 to a location proximal and closely linked to FRAXA. In this study of fragile X fra(X) syndrome families, the DXS105 locus was calculated to be proximal to FRAXA with a maximum lod score of 10.36 at theta = 0.08. DXS105 was also shown to be closely linked to the gene for factor IX (F9)(Z = 11.84 at theta = 0.08) and to DXS98 (Z = 4.91 at theta = 0.04). The order of the loci proximal to FRAXA is most likely centromere-factor IX-DXS105-DXS98-FRAXA-telomere. The use of DXS105 and DXS98 in clinical investigations should significantly increase the accuracy of risk assessment in informative fragile X families.

Partial trisomy 13q identified by sequential fluorescence in situ hybridization.

We report on a 19-month-old boy with partial trisomy 13q resulting from a probable balanced translocation involving chromosomes 1 and 13. The infant presented with omphalocele, malrotation, microcephaly with overriding skull bones, micrognathia, apparently low-set ears, rocker-bottom feet, and congenital heart disease, findings suggestive of trisomy 13. Karyotypic studies from peripheral blood lymphocytes documented an unbalanced karyotype 46,XY,-1,+der(1). The mother's chromosomes were normal, and the father was not available. Conventional cytogenetic techniques were unable to identify the extra material on the terminal 1q. Using fluorescence in situ hybridization (FISH) on the GTL-banded metaphases, the extra material on 1q was identified as the terminal long arm of 13, thus resulting in partial trisomy 13 (q32-qter).

Photoanthropometric analysis of individuals with the fragile X syndrome.

A photoanthropometric method, which enables an objective description of facial structures, was used to examine 31 boys with the fragile X or Martin-Bell syndrome below the age of 12 years. The age range was 1.5 to 12 years with an average age of 6.5 years. Facial parameters were measured from strict frontal and profile photographs of fra(X) syndrome boys and compared with other facial measurements from the same face (e.g. mouth width vs. bizygomatic diameter). We studied 18 photoanthropometric facial parameters following the protocol established by Stengel-Rutkowski et al [1984]. Fourteen indices were calculated and compared with photoanthropometric index standards for age, established from normal children between 0 and 12 years [Stengel-Rutkowski et al, 1984]. Two of the fourteen craniofacial indices, broad palpebral fissures and decreased inner canthal distance, were significantly abnormal.

Rater reliability of fragile X mutation size estimates: a multilaboratory analysis.

Notwithstanding the use of comparable molecular protocols, description and measurement of the fra(X) (fragile X) mutation may vary according to its appearance as a discrete band, smear, multiple bands, or mosaic. Estimation of mutation size may also differ from one laboratory to another. We report on the description of an mutation size estimate for a large sample of individuals tested for the fra(X) pre- or full mutation. Of 63 DNA samples evaluated, 45 were identified previously as fra(X) pre- or full mutations. DNA from 18 unaffected individuals was used as control. Genomic DNA was extracted from peripheral blood, and DNA fragments from each of four laboratories were sent to a single center where Southern blots were prepared and hybridized with the pE5.1 probe. Photographs from autoradiographs were returned to each site, and raters blind to the identity of the specimens were asked to evaluate them. Raters' estimates of mutation size compared favorably with a reference test. Intrarater reliability was good to excellent. Variability in mutation size estimates was comparable across band types. Variability in estimates was moderate, and was significantly correlated with absolute mutation size and band type.

Gonadal function in men with the Martin-Bell (fragile-X) syndrome.

We evaluated testicular function in 15 men with the Martin-Bell (fragile-X) mental retardation syndrome. Macro-orchidism was present in all subjects. Their mean serum LH and FSH levels and plasma testosterone and dihydrotestosterone levels were normal. The mean plasma levels of androstenedione, 17-hydroxyprogesterone, and progesterone were slightly elevated above the normal range, whereas the plasma levels of dehydroepiandrosterone and dehydroepiandrosterone-sulfate were normal. The response in the levels of plasma testosterone following a 5 day period of hCG stimulation was normal in 8 subjects and there was no abnormal accumulation of androgen precursors. The level of 5 alpha-reductase activity and androgen receptor binding was normal in genital skin fibroblasts derived from 3 of these patients. The response of gonadotropin secretion to GnRH stimulation was normal in the 8 men who were tested. Therefore, our data are consistent with the hypothesis that testicular enlargement in men with the Martin-Bell syndrome is not mediated by hormonal factors.

Metacarpophalangeal pattern profile analysis in fragile X syndrome.

We analyzed the metacarpophalangeal pattern profile (MCPP) on 18 male individuals from 16 families with fragile X--fra (X), or Martin-Bell--syndrome and calculated a mean syndrome profile. Fourteen of 18 individuals with fra (X) syndrome had significant positive correlations which indicated clinical homogeneity. Discriminant analysis of individuals with fra (X) syndrome compared with a sample of normal individuals produced a correct classification rate of 88% based on a function of 3 MCPP variables that may provide a useful tool in screening individuals for the fra (X) syndrome. Discriminant and correlation analyses of individuals with Sotos sequence and individuals with fra (X) syndrome did not identify MCPP similarities. Therefore, there was no MCPP evidence in our study of patients with Sotos sequence and fra (X) chromosome expression.

Longitudinal study of cognitive abilities and adaptive behavior levels in fragile X males: a prospective multicenter analysis.

Retrospective longitudinal studies have noted declines in IQ scores in many but not all fra(X) (fragile X) males and females. We report on a prospective investigation of longitudinal changes in cognitive ability (IQ) and adaptive behavior (DQ) in 24 fra(X) males from four test sites. Individuals who were tested ranged in age from 3-15 years. To determine cognitive ability, all males were administered the Stanford-Binet test (4th Edition). To assess adaptive behavior, all males were evaluated using the Vineland Adaptive Behavior Scales. Mean interest interval was 2.3 years. Using identical DNA protocols, all subjects were identified as bearing the fra(X) mutation. Results showed declines in IQ scores in 18/24 (75%) males. Four males showed no change in scores. Declines in DQ scores were noted in 22/24 (92%) of those tested. DQ scores were higher than IQ scores in 20/24 (83%) subjects. From a descriptive cohort analysis, decreases in IQ scores appear to follow a well-defined, negatively decelerating function. Declines in DQ were steeper and more nearly linear. Declining scores are not indicative of regression of intellectual and/or social skills, but of a relative inability to keep pace with their age-normed cohort. We conclude that the fra(X) mutation affects cognitive abilities in a uniform, nonlinear manner comparable to outcomes observed in earlier retrospective studies. Adaptive behavior also declines, but in a more linear fashion.

Lack of association between mutation size and cognitive/behavior deficits in fragile X males: a brief report.

Previously, researchers reported molecular-neurobehavioral or molecular-cognitive associations in individuals with fra(X) (fragile X) mutation. However, not all investigators have noted molecular-behavioral relationships. Consequently, we examined prospectively 30 fra(X) males age 3-15 years from four testing sites to determine whether there was a relationship between mutation size and degree of either cognitive or adaptive behavior deficit. To measure cognitive abilities, all individuals were administered the Stanford-Binet (4th edition) IQ test. To evaluate adaptive behavior (DQ) skills, all individuals were assessed using the Vineland Adaptive Behavior Scale. To determine fra(X) status, genomic DNA from all individuals was extracted and digested with EcoRI and EagI restriction enzymes. Southern blots were prepared and hybridized with the pE5.1 probe. The Pearson correlation coefficient between full mutation size and composite IQ score revealed a nonsignificant, near-zero association (r = 0.06; P > .76). The Pearson coefficient between mutation size and DQ also showed a nonsignificant, near-zero association (r = 0.06; P > .73). We conclude that while fra(X) mutation produces cognitive and behavior deficits in males who inherit the defective gene, there is no relationship between mutation size and degree of deficit.

Is fragile X syndrome a pervasive developmental disability? Cognitive ability and adaptive behavior in males with the full mutation.

In addition to mental retardation (MR), fragile X [fra(X)] syndrome has been associated with various psychopathologies, although it appears that the link is secondary to MR. It has been proposed that individuals with the full mutation be classified as a subcategory of pervasive developmental disorders (PDD). If fra(X) males are to be categorized as PDD, how do they compare with other types of developmental disabilities? We examined 27 fra(X) males aged 3-14 years, from 4 sites in North America. Measures of cognitive abilities were obtained from the Stanford-Binet Fourth Edition (SBFE), while levels of adaptive behavior were evaluated using the Vineland Adaptive Behavior Scales (VABS). Control subjects were sex-, age-, and IQ matched children and adolescents ascertained from the Developmental Evaluation Clinic (DEC) at Kings County Hospital. At the DEC, control subjects were diagnosed as either MR (n = 43) or autistic disorder (AD; n = 22). To compare subjects' adaptive behavior (SQ) with their cognitive abilities (IQ), a ratio of [(SQ/IQ) x 100] was computed. Results graphed as cumulative distribution functions (cdf) revealed that the cdf for AD males, who by definition are socially impaired, was positioned to the left of the cdf for MR controls, as expected. Mean ratio for AD males (70) was lower than for MR males (84). On the other hand, the cdf for fra(X) males was positioned far to the right of either AD or MR controls (mean ratio = 125). Statistical tests showed that SQ of fra(X) males was significantly higher than controls.(ABSTRACT TRUNCATED AT 250 WORDS)