The primary erythermalgia-susceptibility gene is located on chromosome 2q31-32.

Primary erythermalgia is a rare disorder characterized by recurrent attacks of red, warm, and painful hands and/or feet. The symptoms are generally refractory to treatment and persist throughout life. Five kindreds with multiple cases of primary erythermalgia were identified, and the largest was subjected to a genomewide search. We detected strong evidence for linkage of the primary erythermalgia locus to markers from chromosome 2q. The highest LOD score (Z) was obtained with D2S2330 (Z(max) = 6.51). Analysis of recombination events identified D2S2370 and D2S1776 as flanking markers, on chromosome 2q31-32. This defines a critical interval of 7.94 cM that harbors the primary erythermalgia gene. Affected members within the additional families also shared a common haplotype on chromosome 2q31-32, supporting our linkage results. Identification of the primary erythermalgia gene will allow a better clinical classification of this pleomorphic group of disorders.

Terminal deletion of the long arm of chromosome 4 in a mother and two sons.

Deletion of chromosome 4q31-->pter has been characterized as a distinctive malformation syndrome. We report a mother and two sons with deletion of the long arm (q) of chromosome 4 del(4)(q34.2).

Chromosome 1p terminal deletion: report of new findings and confirmation of two characteristic phenotypes.

We report three unrelated patients with small terminal deletions involving 1p36.22-->pter that occurred de novo and compare our patients to the 10 previously reported cases. Although our patients have an identical cytogenetic deletion, patients 1 and 2 share similar clinical features that differ substantially from patient 3. Our patients confirm the existence of two characteristic phenotypes in 1p36.22-->pter deletion. Both phenotypes share some dysmorphic features, but are differentiated by characteristics of growth failure versus macrosomia. In addition, we report the new finding of cardiomyopathy and hydrocephalus in the phenotype associated with growth failure. It is possible that different phenotypic subgroups may exist because of differences in the parental origins of the deleted chromosome or of variations in undetectable amounts of genetic material.

Assignment of the human heart tetrodotoxin-resistant voltage-gated Na+ channel alpha-subunit gene (SCN5A) to band 3p21.

The chromosomal location of SCN5A, the gene encoding the principal voltage-gated Na+ channel expressed in human heart, has been determined by three independent methodologies: somatic cell hybrid mapping, chromosomal microdissection-polymerase chain reaction, and fluorescence in situ hybridization. The SCN5A gene was assigned to the short arm of chromosome 3 (band 3p21) by all three approaches. These data are further evidence that striated muscle Na+ channel genes are dispersed in the genome.

Congenital heart disease in infants with Down's syndrome.

Medical records of 118 newborn infants with Down's syndrome were reviewed to document the types of congenital heart disease (CHD) in those having echocardiography. Of 102 infants having echocardiography, 49 (48%) had heart defects; 47 of these had trisomy 21 and 2 had unbalanced translocation karyotypes. Of the 53 (52%) who did not have heart defects, all had trisomy except 1 with a mosaic karyotype and 1 with a translocation karyotype. The most common heart malformation was an atrioventricular canal, followed in frequency by ventricular septal defect, atrial septal defect, patent ductus arteriosus, and tetralogy of Fallot. Benefits of echocardiography in such infants are early detection of CHD, with aggressive management to prevent future complications, and reassurance to parents if the infant does not have CHD.

Over-representation of the disease associated (CAG) and (CGG) repeats in the human genome.

Expansion of trimer repeats has recently been described as a new type of human mutation. Of the 64 possible trimer compositions, only the CGG and CAG repeats have been implicated in genetic diseases. This study intends to address two questions: (1) What makes the CGG and CAG repeats unique? (2) Could other trimer repeats be involved in this type of mutation? By computer analysis of trimer and hexamer frequency distributions in approximately 10 Mb of human DNA, twenty trimer motifs (ten complementary pairs) have been identified that are the most likely to be expanded. The frequency distribution study also indicated that the expanded trimer motif in Fragile-X syndrome is GGC instead of CGG. DNA linguistics studies revealed that the GGC/GCC and CAG/CTG repeats were over-represented in the human genome. Further analysis of base composition suggested that the CCA/TGG repeats may be involved in the trimer expansion mutation since they possessed many similar characteristics to GGC/GCC and CAG/CTG. The computer aided sequence analysis studies reported here may help to understand the molecular mechanisms of trimer repeat expansion.

Birth defects surveillance: Jefferson County, Alabama, and Uppsala County, Sweden.

Birth defects in live-born infants were documented for 2 years in Jefferson County, Alabama (USA)--1986 and 1987--and in Uppsala County, Sweden--1985 and 1986. A total of 27,561 live births (9,179 white male, 8,728 white female, 4,883 black male, and 4,771 black female infants) occurred in Jefferson County; 6,896 live births (3,535 male and 3,361 female) were recorded in Uppsala County. These newborns were studied to establish a database of birth defects for the two small geographic areas and to study similarities and differences. Rates of hip dislocation, heart malformations, and clubfoot were high in Swedish infants. Similar frequencies of spina bifida and polydactyly were noted in Alabama whites and Swedish infants. Regional registries offer a systematic approach to detection of clustering of specific birth defects, identification of families for further study, location of patients with unique needs, and enhanced coordination of health services, including genetic counseling.

Selection of antisense oligonucleotides on the basis of genomic frequency of the target sequence.

Antisense oligonucleotides (ASOs) are capable of blocking the expression of targeted genes and are potential antitumor and antiviral therapeutic agents. The specificity of ASO gene inhibition is compromised when homology to other sequences allows the selected ASO to bind to nontargeted mRNAs. To reduce this nonspecific activity, an ASO should target a sequence that is predicted to be unlikely to occur in other mRNAs. The probability of a sequence being unique can be predicted by determining the genomic frequency of short stretches of sequences contained within the target sequence. Two computer programs, OLIGOMER and HEXAGRAPH, were developed for this analysis. OLIGOMER was used to analyze the genomic frequencies of di-, tri-, and hexamers in more than 24 million nucleotides from 8 different genomes in GenBank. A mathematical model was developed that predicts the genomic frequency of longer oligomers on the basis of the observed frequencies of shorter oligomers. The second program, HEXAGRAPH, was used to graphically display the genomic frequency data of a selected target gene. The computational tools developed in this study may help to design more efficient ASOs by decreasing their nonspecific binding activity.

Relationship between amniotic fluid and maternal blood nutrient levels.

To study the relationships between amniotic fluid and maternal blood nutrient concentrations, we obtained amniotic fluid and blood samples simultaneously from 76 pregnant women at around 17 weeks gestation. Folate and vitamin B-12 levels were measured by microbiological assay and radioassay, respectively, and zinc, copper and iron levels by atomic absorption spectrophotometry. Mean concentrations of plasma and red blood cell (RBC) folate and plasma copper of the pregnant women were 38 (+/- 1, SD), 1,501 (+/- 374) nmol/L, and 32.7 (+/- 4.8) mumol/L, respectively, all of which were higher than those of healthy non-pregnant controls (p < 0.001). Mean concentrations of plasma vitamin B-12, zinc and iron levels and RBC zinc were 320 (+/- 130) pmol/L, 12.2 (+/- 2.3), 21.7 (+/- 6.1) and 177 (+/- 30) mumol/L and these were similar to those of non-pregnant controls. Amniotic fluid folate, zinc, copper and iron concentrations were 21 (+/- 13) nmol/L, 1.4 (+/- 0.6), 1.7 (+/- 0.6) and 6.8 (+/- 2.1) mumol/L, respectively, which were significantly lower than plasma levels (p < 0.001). However, this relationship was reversed for vitamin B-12 (650 +/- 420 pmol/L). Significant correlations were found between amniotic fluid and maternal plasma and RBC for folate, and between amniotic fluid and maternal plasma for vitamin B-12 (p < 0.001). No such correlations were observed for zinc, copper and iron. There was no correlation between amniotic fluid and/or blood nutrient concentrations and pregnancy outcome including birth weight of infants.

Molecular and cytogenetic investigation of complex tissue-specific duplication and loss of chromosome 21 in a child with a monosomy 21 phenotype.

Several recent molecular studies have suggested that the clinical phenotype of Down syndrome may be due to triplication of 21q22 [McCormick et al., 1989] as initially suggested by Niebuhr [1974], and perhaps just 21q22.2 [Korenberg et al., 1989, 1990; Rahmani et al., 1989]. Recently, we studied a patient with a phenotype inconsistent with Down syndrome, whose lymphocyte karyotype on several occasions detected only 46,XX,-21, + dic(21)(qter----p11::p11----qter). Combined karyotype and molecular studies on both lymphocytes and fibroblasts allowed correct identification of the abnormality as a complex monosomy/trisomy 21 mosaicism involving a marker derived from idic (21) (p11), and probable assignment of a maternal origin for the error(s). The patient's phenotype was found to be most consistent with monosomy 21. Detailed study of our patient underscores (1) the need for confirmation that there is phenotype/karyotype correlation and (2) the usefulness of molecular analyses to complement the cytogenetic interpretation of marker chromosomes.

Autosomal dominant erythromelalgia.

We present a kindred of 29 persons affected with erythromelalgia (erythermalgia) in 5 generations. This paper updates the family reported by Burbank et al. [1966]. Patients have symptoms of intermittent intense burning limb pain related to increased skin temperature. No successful treatment has been identified, and the pathogenetic mechanism has not been established. Most affected individuals are female.

Nutrient levels in amniotic fluid from women with normal and neural tube defect pregnancies.

We analyzed nutrient levels in amniotic fluid obtained during the second trimester of normal, uncomplicated pregnancies from 221 women who delivered apparently healthy infants and from 8 with neural tube defect (NTD) pregnancies. Folate was measured by microbiological assay, vitamin B12 by a radiobinding method, and zinc, copper and iron by atomic absorption spectrophotometry. We found that the mean amniotic fluid nutrient levels of normal pregnancies were 24.7 nmol/l for folate, 600 pmol/l for vitamin B12, and 1.7, 1.9, and 9.0 mumol/l for zinc, copper and iron, respectively. Amniotic fluid folate, zinc, copper and iron levels of NTD pregnancies were similar to those found during normal pregnancy, however, vitamin B12 levels were markedly lower than those of normal pregnancies.

Parental age in the blepharophimosis, ptosis, epicanthus inversus, telecanthus complex.

Maternal and paternal age and birth order of 14 sporadic cases of the autosomal dominant blepharophimosis-ptosis-epicanthus inversus-telecanthus (BPEI) phenotype were compared to similar statistics from control individuals. Correlation coefficients were determined for paternal age and incidence, maternal age and incidence, and birth order and incidence. The partial correlation coefficient of the father's age and incidence with maternal age and birth order held constant was -0.02 and that for the mother's age and incidence with paternal age and birth order held constant was 0.57. Maternal age seems to have a stronger influence than the paternal age in this group of BPEI patients.

Interstitial deletion of chromosome 1 [del(1)(q25q32)] in an infant with prune belly sequence.

Relatively few cases of deletion 1q have been reported. These cases have been divided into three groups according to assigned breakpoints. They include proximal interstitial, intermediate interstitial, and terminal deletions. We present a male infant with an interstitial deletion of 1q with breakpoints determined by GTG banding as q25 and q32. Comparison with similar case reports suggests common physical features which include microcephaly, growth retardation, developmental delay, clinodactyly, and genital anomalies in affected males. However, no characteristic phenotypic appearance is definable. The infant also presented with prune belly sequence (PBS) with Potter facies. Fetal ascites, as noted in this case on prenatal ultrasound, appears to be an early factor in the pathogenesis of PBS. Therefore, detection of fetal ascites should suggest the presence of the PBS association and the need for more extensive prenatal evaluation.