Biomedical subjects
Publications and source records attributed to P Mamunes.
We report on a newborn girl with holoprosencephaly, microcephaly, absent right radius, and other anomalies with an 46,XX,i(18q) chromosome constitution. This is the first report of an i(18q) in syndromal alobar holoprosencephaly.
Isolated neuraminidase deficiency is a member of the relatively rare group of storage disorders known as glycoproteinoses. We report the long-term natural history of the disease in one of the first patients described in the literature. An unusual feature of the disease is the abrupt onset and fulminant nature of the nephrotic syndrome, complications of which caused the demise of our patient. Pathological examination of the kidneys from this child revealed renal epithelial cell damage, most marked in the membranes of the glomeruli and proximal tubules, findings which are consistent with the high sialic acid content of the membrane in these areas of the nephron. Chemical analysis indicated that the bulk of the stored material in the kidney was in the form of polar sialyloligosaccharides of high molecular weight. On the basis of our experience, as well as the previous reports of neuraminidase-deficient patients with nephropathy, we propose a nephropathic phenotypic variant of type 2 infantile sialidosis.
The Smith-Lemli-Opitz syndrome (SLOS) and the Meckel syndrome (MS) have been regarded as separate autosomal recessive entities. Recently, overlap of these two syndromes has been discussed. A sibship containing a probable new syndrome with features reminiscent of the SLOS and the MS is presented. The literature is reviewed with regard to the frequency of various malformations in these syndromes. Clinical manifestations and cerebellar abnormalities in these sibs are similar to those described in the Joubert syndrome (JS). These three cases may represent a new syndrome with features in common with SLOS, MS, and JS resulting from the same mutant gene, which exhibits considerable pleiotropy.
A syndrome of spastic paresis, mental retardation and glaucoma has been described only once previously (Heijbel & Jagell 1981). We describe three brothers, products of a marriage between first cousins once-removed, who appear to have the same syndrome. The brothers are not dysmorphic but they have slowly progressive spastic paresis, moderate mental retardation and glaucoma with secondary cataracts. Documentation of a second consanguineous kindred with this triad of features supports the view that this is a distinct entity with an autosomal recessive mode of inheritance.
Individuals with the Aarskog syndrome have shortness of stature, round face, hypertelorism, short fingers and hands, and flat feet; males have a shawl scrotum. Pedigrees have consistently suggested X-linked inheritance, although the possibility of autosomal dominant inheritance was not excluded. We present a father and two sons affected with the Aarskog syndrome. Thus, the Aarskog phenotype either is genetically heterogeneous or a sex-influenced autosomal dominant trait as shown by the deficiency of affected females. An ascertainment bias for males could be owing to the shawl scrotum. We have reviewed the literature and tabulated findings in 82 previously reported cases.
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Children with inborn errors of urea synthesis accumulate ammonium and other nitrogenous precursors of urea, leading to episodic coma and a high mortality rate. We used alternative pathways for the excretion of waste nitrogen as substitutes for the defective ureagenic pathways in 26 infants. These pathways involve synthesis and excretion of hippurate after sodium benzoate administration, and of citrulline and argininosuccinate after arginine supplementation. The children were treated for seven to 62 months; 22 survived. The mean plasma level of ammonium ( +/- S.E.) was 36 +/- 2 mumol per liter, and that of benzoate was 1.5 +/- 1.0 mg per deciliter. Alternative pathways accounted for between 28 and 59 per cent of the total "effective" excretion of waste nitrogen. Nineteen infants had normal height, weight, and head circumference, and 13 had normal intellectual development. Activation of alternative pathways of waste nitrogen excretion can prolong survival and improve clinical outcome in children with inborn errors of urea synthesis.
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Treatment with 1,25-dihydroxyvitamin-D3 and phosphorus supplementation for as long as 48 months was evaluated in six patients with renal hypophosphatemic rickets. Previous phosphorus supplementation of 1,800 to 4,000 mg/sq m of body surface area per day was continued while 1,25-dihydroxyvitamin-D3 at 17 to 80 ng/kg of body weight per day was given orally in place of vitamin-D2. The serum calcium concentration stayed within the normal range in the majority of patients, while the serum phosphorus concentration rose from 2.5 +/- 0.4 to 3.4 +/- 1.2 mg/100 ml after one month (P < .01). With rare exceptions, serum alkaline phosphatase and parthyroid hormone concentrations stayed normal throughout the study. Healing of rickets was demonstrated by radiography. In five patients, growth velocity was evaluated for 12 months before and after therapy. Growth accelerations were 123% to 235% of that expected for changes in chronologic age and 114% to 200% expected for changes in bone age after therapy. Orally administered, 1,25-dihydroxyvitamin-D3 increased renal calcium excretion and calcium retention was achieved by virtue of the decreased fecal calcium loss. In contrast, 1,25-dihydroxyvitamin-D3, even at doses up to 4 micrograms/day (80 ng/kg/day) did not significantly alter renal phosphaturia. The phosphorus retention was therefore achieved as the result of the decreased fecal phosphate excretion. The absence of hypercalcemia even at high doses of 1,25-dihydroxyvitamin-D3 and the enhanced linear growth support the long-term therapeutic value of 1,25-dihydroxyvitamin-D3 in renal hypophosphatemic rickets.
Improved approaches to the problem of heterozygote detection for phenylketonuria (PKU) were developed in this study. The discrimination was based on 85 obligate heterozygotes and 45 controls who were neither pregnant nor on birth control medication. The best separation between hetrozygotes and normals was achieved with a linear discriminant function involving the logarithms of the serum concentrations of phenylalanine, tyrosine, and tryptophan. The theoretical overlap area between the distributions of heterozygotes and controls based on the above function, was 3.75%. In the 19 obligate hetrozygotes and 13 controls who were either pregnant or on birth control medication, the best separation was achieved with a linear discriminant function involving the logarithms of the serum concentrations of phenylalanine and tyrosine. The theoretical overlap area was 8.23%. The genetic accuracy of the discriminant function was confirmed by testing the results with parental-child exclusions, segregation analysis, and the frequency of heterozygosity in nonrelated collateral spouses. Finally, there was evidence suggesting that the antihypertensive agent, aldomet, alters serum tyrosine and tryptophan levels.
We have presented the morbid anatomy of a case of Sandhoff's disease and have attempted to outline morphologic differences which distinguish this entity from other GM2 gangliosidoses. Yet, it may be well to maintain a sceptical eye. The anatomic differences among Tay-Sachs disease and its variants are more quantitative than qualitative and are overshadowed by the similarities. For these reasons, a definitive diagnosis must rest with the biochemist. Nevertheless, if many bizarre MCB's are encountered, the enzyme defect may be expected to differ from that of classical Tay-Sachs disease and, when seen in endothelial cells, they favour Sandhoff's disease. More importantly, if prominent visceral storage is found, and especially if it extends beyond the reticuloendothelial system to involve such selective sites as the kidneys and pancreas, Sandhoff's disease should immediately come to mind. For the pathologist, it is this latter point which more readily sets apart Sandhoff's disease from related GM2 gangliosidoses.
A patient with a double partial trisomy 20 and 21 with mild mental retardation and multiple congenital anomalies is presented. Despite trisomy for a substantial portion of chromosome 21, the patient showed only minor stigmata compatible with Down syndrome.
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In order to determine if prolonged, significant transient neonatal tyrosinemia (TNT) is injurious to the developing central nervous system, 15 term infants who had suffered from this disorder for a mean duration of 50 days underwent comprehensive psychometric evaluations at a mean (+/- 1 SD) age of 56.5 +/- 7.8 months. Their mean maximum detected tyrosine level had been 25.8 mg/dl (range, 13.6 to 42.0) and their defect was considered secondary to a combination of a high protein formula intake and a lack of supplemental vitamin C. Compared to a control group, significantly lower mean scores were obtained by the TNT group on the McCarthy Scale of Children's Abilities (77.1 vs. 92, P = .008) and the Illinois Test of Psycholinguistic Ability (92.3 vs. 109.9, P = .002). Performance scores varied inversely with the duration of TNT. Although these children are not classifiable as "mentally retarded," TNT may cause specific learning disabilities. There is, therefore, a need to determine the frequency of TNT in infants fed evaporated milk and other high-protein milk formulas and to develop ways to prevent its occurrence.
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