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R H Lindenbaum

Publications and source records attributed to R H Lindenbaum.

At least 37 records · Page 2Linked to original sources
PubMed1989

The nature of the defect in cobalamin G mutation.

Cobalamin G mutation (cblG) typically presents as a severe megaloblastic anemia during the first few weeks of life. The anemia responds completely to treatment with high doses of Cbl but the neurologic manifestations respond more slowly and not always completely. Cultured fibroblasts from two affected infants and virus-transformed lymphoblasts from one of the infants expressed the following: poor growth in the absence of methionine, the ability to take up and internalize Cbl bound to transcobalamin II, impaired synthesis of methionine from homocysteine, the ability to bind incoming Cbl to the respective coenzymes, but an inability to synthesize methylcobalamin in spite of a normal capacity to synthesize adenosylcobalamin. The in vitro activity of the methyltransferase dependent on methylcobalamin of cell extracts varied from low to high depending on the conditions of culture and assay. The cblG cells were unusually sensitive to the concentration of adenosylmethionine in the assay. More adenosylmethionine was required by cblG cells to achieve the same level of enzyme activity as control cells and high concentrations of adenosylmethionine did not suppress activity as in control cells. It was postulated that the defect in cblG is in the metabolism of adenosylmethionine, an essential substance for the synthesis of methionine from homocysteine.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1988

Fraser syndrome (cryptophthalmos-syndactyly syndrome): a review of eleven cases with postmortem findings.

Detailed postmortem findings from 11 cases of probable Fraser (cryptophthalmos-syndactyly) syndrome are reported. Eight cases presented as neonatal deaths, one as a stillbirth, and there were 2 midtrimester fetuses. All of the cases had ocular, otic, digital, laryngeal, and renal abnormalities. Details of the pregnancies and sibship data are also reported. The possibility of prenatal diagnosis for this syndrome is discussed.

Abortion, Spontaneous↗
PubMed1988

Regional assignment of the gene coding for human sucrase-isomaltase (SI) to chromosome 3q25-26.

The gene coding for sucrase-isomaltase (SI) has recently been mapped to chromosome 3 using a cDNA probe to analyse DNA from somatic cell hybrids (Green et al. 1987). We have now used this same cDNA probe to obtain a regional localization of this gene. In situ hybridization to normal metaphase chromosomes and to chromosomes from individuals with balanced translocations suggests a regional assignment to chromosome 3q25-26.

Chromosome Mapping↗
PubMed1988

Pulmonary agenesis as part of the VACTERL sequence.

Pulmonary agenesis is an uncommon anomaly that has been reported in isolation and in association with other congenital defects. Such defects include oesophageal atresia, cardiac malformation, horseshoe kidney, and anal atresia. Over a period of three years we have seen five neonates or fetuses with unilateral agenesis of the lung. All the cases had three or more anomalies seen in the VACTERL sequence in addition to the pulmonary atresia. None had a tracheo-oesophageal fistula. None were the products of consanguineous marriages. There had been no recurrence of this range of defects in any of the families at the time of writing. We suggest that pulmonary agenesis may occur as an alternative to tracheo-oesophageal fistula in the VACTERL sequence.

Abnormalities, Multiple↗
PubMed1987

Pre-eclampsia and trisomy 13: a possible association.

Pregnancies of fourteen women who gave birth to babies with trisomy 13 were studied retrospectively for evidence of pre-eclampsia, with twenty-eight controls matched for age and parity. Of the five nulliparous women who subsequently gave birth to a baby with trisomy 13 all had had severe pre-eclampsia, compared with none of the control group. The records of eleven women whose first babies had had trisomy 18 (four) or trisomy 21 (seven) were also studied with appropriate controls and none of these pregnancies had been complicated by pre-eclampsia. Development of pre-eclampsia may be influenced by a gene or genes on fetal chromosome 13.

Adult↗
PubMed1987

Parental decisions regarding termination of pregnancy following prenatal detection of sex chromosome abnormality.

In the period of a retrospective study (1970-1984 inclusive) forty cases of sex chromosome aneuploidy were identified at amniocentesis in Oxford, England and in Kuopio, Finland; 25 of these pregnancies were subsequently terminated. A decision to continue was made more often for XYY and XXX karyotypes, by older mothers and older fathers, by couples with more previous children, and by couples living in England. A decision to terminate was made more often for XXY and non-mosaic 45,X karyotypes, by younger mothers and younger fathers, by couples with few previous children, in all cases with abnormal ultrasound findings, when post-amniocentesis counselling was given by an obstetrician, and by couples living in Finland. Previous miscarriages, or terminations of pregnancy, previous problems with infertility, marital status, or the type of counselling given before amniocentesis, appeared not to influence a couples' decision. Religious and ethical ideas were not studied systematically at the time and cannot be reported on.

Abortion, Eugenic↗
PubMed1987

Trisomy 18 and maternal serum and amniotic fluid alpha-fetoprotein.

Maternal serum and amniotic fluid alpha-fetoprotein levels were studied retrospectively in a total of 58 pregnancies with trisomy 18. In those pregnancies uncomplicated by either fetal exomphalos or neural tube defect the midtrimester maternal serum alpha-fetoprotein (MSAFP) levels were markedly reduced, the median value for 38 such pregnancies being 0.6 multiples of the median (MoM). Trisomy 18 with exomphalos was associated with a higher median MSAFP, but still within the normal range: 1.1 MoM, (nine pregnancies); trisomy 18 with exomphalos and neural tube defect (NTD) was associated with grossly raised levels: median MSAFP was 4.5 MoM (three pregnancies). Amniotic fluid alpha-fetoprotein (AFAFP) levels were normal in uncomplicated trisomy 18 pregnancies: median AFAFP, for 19 pregnancies, was 1.1 MoM. Exomphalos alone, or together with neural tube defect, was associated with greatly elevated levels of AFAFP; for exomphalos alone median AFAFP was 9.59 MoM (four pregnancies), and for exomphalos with neural tube defect the median AFAFP was 23.95 Mom (three pregnancies). Screening with low and high MSAFP, routine ultrasound, and amniocentesis on all women aged 35 years or over, together might identify over 50 per cent of pregnancies with trisomy 18.

Adult↗
PubMed1987

Pitted enamel hypoplasia in tuberous sclerosis patients and first-degree relatives.

Thirty-six families with tuberous sclerosis (TS) including 49 affected persons and 68 apparently unaffected first-degree relatives were examined for dental abnormality. Fifty unrelated controls were similarly examined. Clinically observed multiple enamel pits (pitted enamel hypoplasia) were noted in 71% of persons with typical TS and in one out of 10 "atypical" cases. Enamel pits were rarely seen, and in small numbers only, in the control series, and they were rare in the otherwise apparently normal TS first-degree relatives. However, one parent and one half-sib of persons with typical TS, but themselves without other signs of TS, were found to have multiple enamel pits. Examination for pitted enamel hypoplasia should be made in all persons suspected of having TS and in all close relatives; enamel pits are a valuable clinical sign and may identify otherwise unsuspected carriers of the gene within the family.

Adult↗
PubMed1985

The FG syndrome: 7 new cases.

The X-linked FG syndrome is characterised by mental retardation, congenital hypotonia and constipation (which may both be severe), structural anal anomalies and relative macrocephaly in some, and an unusual and characteristic facial appearance. We describe 7 males from 4 families. One had anal stenosis. Two of the mothers and one sister show probable carrier manifestations. The features of the FG syndrome are individually non-specific. We emphasize that the characteristic combination of features is needed to avoid overdiagnosis.

Adult↗
PubMed1985

Amniotic bands in connective tissue disorders.

Amniotic bands are described in two children with Ehlers-Danlos syndrome type IV and in one with severe osteogenesis imperfecta. Since the basic defect in both of these disorders rests in collagen, which constitutes the main component of the load bearing amnion, it is proposed that these cases provide further insight into the pathogenesis of amniotic bands.

Adult↗
PubMed1985

The prevalence of translocations in parents of children with regular trisomy 21: a possible interchromosomal effect?

It has been suggested that translocations, and perhaps other chromosome rearrangements, disturb meiotic disjunction of uninvolved chromosome pairs and predispose to trisomic offspring. If so, then one would expect an excess of translocations not involving chromosome 21 among the parents of regular trisomic Down's syndrome patients. Such translocations have been reported, but mostly as anecdotal single case reports or very small series. In an attempt to collect a larger series, a collaborative study of regular Down's syndrome families was made in southern England. This was retrospective, and covered periods of 7 to 10 years since 1970. The number of regular trisomy families investigated was 1454. Only 945 of the 2908 parents were karyotyped, and 10 balanced reciprocal translocations not involving chromosome 21 were identified, together with one Robertsonian (13q14q). Expressing these as percentages of the parents tested (945), prevalences are as follows: reciprocals 1.06%, Robertsonians 0.11%, and all translocations 1.16%. Expressed as percentages of the total parents (2908), tested and untested, the prevalences are 0.34%, 0.03%, and 0.37% respectively. The 'true' prevalences, that is what would have been found had all parents been tested, must lie between these two sets of figures. The prevalence of reciprocal translocations exceeds that found for consecutive banded newborn infants, which is 0.16%, and this excess may reflect a real interchromosomal effect. Robertsonian translocations in the banded newborn series are at a frequency of 0.11%, identical to that found in the tested parents of regular trisomics. Interpretation of these figures is critically dependent upon the real prevalence of translocations among the newborn, estimates of which increase as technical methods are improving.

Adult↗
PubMed1984

Maternal serum alpha-fetoprotein measurement: a screening test for Down syndrome.

The median maternal serum alpha-fetoprotein (AFP) level at 14-20 weeks' gestation in 61 pregnancies associated with Down syndrome was 0.72 multiples of the median (MoM) value for a series of 36 652 singleton pregnancies unaffected by Down syndrome or neural-tube defect--a statistically significant reduction. The difference is great enough to form the basis of a screening test. By selecting for amniocentesis women with serum AFP levels less than or equal to 0.5 MoM at 14-20 weeks' gestation (excluding any of these that ultrasound cephalometry shows to have been due to the overestimation of gestational age) 21% of pregnancies with Down syndrome would be identified as well as 5% of unaffected pregnancies. If amniocentesis were offered to all women aged 38 years or more and, in addition, to younger women with serum AFP below specified maternal age-dependent cut-off levels (less than or equal to 1.0 MoM at 37 years, less than or equal to 0.9 at 36, less than or equal to 0.8 at 35, less than or equal to 0.7 at 34, less than or equal to 0.6 at 32-33, less than or equal to 0.5 at 25-31) 40% of pregnancies with Down syndrome and 6.8% unaffected pregnancies would be selected.

Adult↗
PubMed1984

Tuberous sclerosis: a new estimate of prevalence within the Oxford region.

Within the counties administered by the Oxford Regional Health Authority (population 2 328 100) the prevalence of tuberous sclerosis was estimated as 1 in 29 900 for persons under 65 years of age. For the population below 30 years of age the prevalence was 1 in 21 500 and for children under 5 years 1 in 15 400. Cases were ascertained through the records of the Department of Medical Genetics at Oxford and the Tuberous Sclerosis Association of Great Britain and also by a questionnaire sent to selected consultants within the region. A previous estimate of prevalence within the region was 1 in 100 000. This study suggests that the prevalence at birth might be even higher than 1 in 15 000.

Adolescent↗