Eszter Vamos

Isodisomy of chromosome 6 in a newborn with methylmalonic acidemia and agenesis of pancreatic beta cells causing diabetes mellitus.

Isodisomy (ID) is a genetic anomaly defined as the inheritance of two copies of the same genetic material from one parent. ID in an offspring is a rare cause of recessive genetic diseases via inheritance of two copies of a mutated gene from one carrier parent. We studied a newborn female with a mut(o) of methylmalonic acidemia and complete absence of insulin-producing beta cells in otherwise normal-appearing pancreatic islets, causing insulin-dependent diabetes mellitus. The patient died 2 wk after birth. Serotyping of the HLA antigens, DNA typing of HLA-B and HLA class II loci, study of polymorphic DNA markers of chromosome 6, and cytogenetic analysis demonstrated paternal ID, involving at least a 25-centiMorgan portion of the chromosome pair that encompasses the MHC. ID probably caused methylmalonic acidemia by duplication of a mutated allele of the corresponding gene on the chromosome 6 inherited from the father. It is also very likely that ID was etiologically related to the agenesis of beta cells and consequent insulin-dependent diabetes mellitus in our patient. We thus speculate on the existence of a gene on chromosome 6 involved in beta cell differentiation.

Infantile form of sialic acid storage disorder: Clinical, ultrastructural, and biochemical studies in two siblings

We describe two sibs with coarse facies, hepatosplenomegaly, prominent psychomotor retardation and unexpectedly fair complexion. Ultrastructural studies of conjunctival, skin, bone marrow and liver biopsies from these individuals showed generalized lysosomal storage of polysaccharidelike material, i.e., membrane bound inclusions containing sparse, fibrillo-granular material. Biochemical analyses of urine and cultured fibroblasts from these patients revealed increased levels of free (unbound) sialic acid.The ultrastructural and biochemical findings in these sibs are similar to those previously found in Salla disease, however, the clinical course is much more severe. It is concluded that these children represent a new pathogenetic entity whose basic defect is still to be defined.

Further evidence for autosomal dominant inheritance and ectodermal abnormalities in Kabuki syndrome

Most cases with Kabuki syndrome (KS) were reported sporadically. Recently, a few familial cases of KS were reported. This report provides further evidence that the KS is inherited as a dominant trait with variable expressivity. The proposita is an 18-month-old girl with facial findings characteristic of Kabuki syndrome, prominent fingertip-pads, a midsagittal cleft of vertebral body D4, hypotonia, and psychomotor retardation. Her mother had a similar facial appearance, prominent, cup-shaped ears, an abnormal dentition, early breast development, and low-normal intelligence. Because mother and daughter both had evident Kabuki syndrome, we conclude that KS in this family is inherited as a dominant trait. Further family history supports this finding. Microscopic examination of the hair of the proposita shows abnormalities consisting of trichorrhexis nodosa, twisting of the hairshafts, and irregularity of the diameter of the hair, as was described recently in a patient with KS. This could be another occasional finding in this syndrome, but further studies are required. The presence of abnormal hair, nails, and the commonly described tooth abnormalities in KS further suggest ectodermal involvement in this syndrome.

Acrocallosal syndrome in Algerian boy born to consanguineous parents: Review of the literature and further delineation of the syndrome

We present a 17-month-old boy with the acrocallosal syndrome. He was born to consanguineous parents. Abnormal findings included agenesis of the corpus callosum, a ventricular septal defect (VSD), postaxial polydactyly of fingers, cleft soft palate, intestinal malrotation, large anterior fontanelle, prominent forehead, hypertelorism, epicanthic folds, short nose and mandible and preauricular skin tags, mixed hearing loss, laryngomalacia, and growth and severe motor and mental retardation. A review of previous reports on the acrocallosal syndrome shows considerable clinical variability; minimal diagnostic criteria are proposed. A developmental field defect with disturbance of midline development is suggested.

Fatal cytochrome c oxidase-deficient myopathy of infancy associated with mtDNA depletion. Differential involvement of skeletal muscle and cultured fibroblasts

The classification of mitochondrial diseases remains controversial on account of their clinical and biochemical polymorphism, but the progress of genetics and immunocytochemistry led recently to the identification of well-defined entities (DiMauro et al 1990). The various types of cytochrome c oxidase (COX) deficiency affecting muscle include in their neonatal expression a benign and a malign form according to the pattern of the enzyme-deficient subunits (Tritschler et al 1991)

A mitochondrial DNA microdeletion in a newborn girl with transient lactic acidosis.

The human mitochondrial DNA (mtDNA) genome (16.6 kb) is exclusively involved in the mitochondrial energy generation pathway of the cell. Therefore, knowledge of the mitochondrial genome and its DNA alterations is essential in identifying functional defects of the respiratory chain. During the last decade a growing list of mitochondrial point mutations, deletions and duplications have been associated with various degenerative diseases. We have identified a microdeletion in the mtDNA of lymphocytes and cultured skin fibroblasts of a baby girl. The newly discovered deletion is located at nucleotides 9204-9205 of the mt-ATPase subunit 6 gene and removes the cleavage site between the ATPase 6 and COIII mRNAs. This is of interest because these mRNAs are normally cleaved apart from a polycistronic transcript in the absence of an intervening tRNA, in what might be a novel mechanism for control of gene expression.

Alterations in cultured fibroblasts of sibs with an infantile form of a free (Unbound) sialic acid storage disorder

Summary: Cultured fibroblasts from two sibs with generalized hypertonia, hepatosplenomegaly, and psychomotor retardation within the first year of life were found to have unusual morphologic features. When examined by phase microscopy, the unstained and unfixed cells contained a large number of vacuolated structures whose gross appearance resembled that of a honeycomb in the cell cytoplasm. Electron microscopy studies, following fixation, showed the “honeycombing” to be the result of numerous, closely packed, cytoplasmic, membrane-bound vacuoles. In some of these structures the remains of fibrillogranular material could be detected.Biochemical analysis of crude sonicates of these cells revealed increased levels (4–7 × N) of an acid soluble component that reacted with thiobarbituric acid. Analysis of trimethylsilyl derivatives of this material by gas liquid chromatography and mass spectrometry showed it to be indistinguishable from sialic acid (N-acetylneuraminic acid).Quantitation of this material from the cells of one of the sibs after isolation on a Dowex column yielded 39.8 nmoles of free (unbound) sialic acid per mg protein whereas normal fibroblasts had 1–2 nmoles per mg. Bound sialic acid levels were at the upper limits of normal (24.8 versus 11–23 nmoles per mg protein). The concentration of cytidine monophosphate-sialic acid was normal.After incubation of the patients fibroblasts with [3H]-N-acetyl-mannosamine for 72 h, there was a 7-fold increase (compared to normal fibroblasts) in the amount of radioactivity in free sialic acid present in the acid soluble fraction. The amount of labeled, bound sialic acid in the acid-insoluble pool, however, was the same in both patient and control fibroblasts.

Multiple sulphatase deficiency with early onset

This male infant was first brought to attention in the neonatal period because he presented clinical and radiological evidence of multiple bone deformities. He was readmitted at 2 1/2 months for hydrocephaly, hepatosplenomegaly and poor somatic and psychomotor development. In addition, coarse facies, corneal opacities and stiff joints were noticed. Bone X-ray anomalies and vacuolized lymphocytes supported the clinical presumption of lysosomal storage disorder. The diagnosis of multiple sulphatase deficiency rests on the presence of MPS and sulphatides in the urine, the finding of a mixed storage process in conjunctival biopsy and the demonstration of deficiencies in arylsulphatases A, B, C, iduronate sulphatase and heparan sulphatase in serum, leukocytes and cultured fibroblasts.

Feingold syndrome: Report of a new family and review

Feingold syndrome (or oculodigitoesophagoduodenal syndrome; Microcephaly, Mesobrachyphalangy, Tracheo-esophageal fistula syndrome) is a dominantly inherited combination of hand and foot abnormalities, microcephaly, esophageal/duodenal atresia, short palpebral fissures and learning disabilities, first reported in 1975 (MIM 164280). We report on the seventh family with Feingold syndrome. The propositus is a male infant with esophageal and duodenal atresia, brachymesophalangy of the fifth fingers, bilateral syndactyly of toes 4-5 (and 2-3), relative microcephaly, and facial anomalies. His mother also has microcephaly, similar facial appearance, short fifth fingers with single flexion crease, syndactyly of toes 4-5, and learning disabilities. The maternal sister, brother, and grandmother of the propositus have the same phenotype. The 7 families with Feingold syndrome are reviewed. Intestinal (esophageal/duodenal) atresia/obstruction occurs in approximately 1/3 of the patients with Feingold syndrome.

Vasopressin and gonadotropin deficiency in a boy with the ectrodactyly‐ectodermal dysplasia‐clefting syndrome

A boy presented with ectrodactyly (lobster claw deformity), bilateral cleft lip and palate, semilobar holoprosencephaly and microcephaly, associated with congenital hypogonadotropic hypogonadism and central diabetes insipidus. Other aspects of pituitary function were normal. We suggest that the ectrodactyly‐ectodermal dysplasia‐clefting syndrome can be associated with a variety of hypothalamo‐pituitary dysfunctions, in addition to the already described isolated growth hormone deficiency.