Biomedical subjects
Publications and source records attributed to Richard Kellermayer.
An unbalanced Y;autosome translocation leading to a male with a 45,X karyotype is rare with about 30 published cases. A male with a 45,X karyotype as a result of a unique, submicroscopic, unbalanced Y;16 translocation is presented with alpha-thalassemia/mental retardation syndrome.
BACKGROUND: Mutations of the human helicase gene RECQL4 have been identified in a subset of patients with Rothmund-Thomson syndrome (RTS) and in children with the diagnosis of RAPADILINO syndrome (RAdial hypoplasia/aplasia, PAtellar hypoplasia/aplasia, cleft or highly arched PAlate, DIarrhea and DIslocated joints, LIttle size [>2 SDs below the mean in height] and LImb malformation, and slender NOse and NOrmal intelligence). While many features of the 2 genetic disorders overlap, poikiloderma--a hallmark of RTS--has been described as generally absent in RAPADILINO syndrome. OBSERVATIONS: We report herein a patient with RTS who carries a truncating mutation and a newly identified missense mutation of RECQL4. The proband uniquely developed all criteria of RAPADILINO in addition to his prominent skin findings. CONCLUSIONS: Patients with RTS may possess all features of RAPADILINO. Consequently, a genetic approach to RTS and RAPADILINO could be beneficial. This approach may provide a better understanding of the wide variety of related phenotypic findings and improve prognostics.
Pure gonadal dysgenesis or Swyer syndrome is a sex-reversal disorder resulting from embryonic testicular regression sequences especially during the first few weeks of fetal life and is induced by mutations in the SRY gene. In the present report, we describe a nonmosaic XY sex-reversed female with pure gonadal dysgenesis. Molecular analysis using sequential PCR to detect Y chromosomal microdeletions showed the presence of SRY, ZFY and AZFa, b and c regions. Automated sequencing of the SRY region revealed a new mutation (deletion of A (adenine) in codon 82 at position +244), leading to a frame shift mutation within the helix I of the HMG-box domain. This mutation generates a truncated protein and is very likely to produce an impairment of SRY DNA binding activity. The present findings further support the functional importance of the putative DNA binding activity of the SRY HMG-box domain.
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Glucose re-addition to carbohydrate starved yeast cells leads to a transient elevation of eytosolic calcium (TECC). Concomitantly, a cytosolic proton extrusion occurs through the activation of the vacuolar H(+)-ATPase and the plasma membrane H(+)-ATPases. This study addressed the dissipation of the TECC through intracellular compartmentalization and the possible affects of the H(+)-ATPases on this process. Both the vacuole and the Golgi-ER apparatus were found to play important roles in distributing calcium to internal stores. Additionally, the inhibition of cytosolic proton extrusion augmented cytosolic calcium responses. A model where pH dependent cytosolic calcium buffering plays an important role in the dissipation of the TECC in Saccharomyces cerevisiae is proposed.
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Previous studies have suggested that yeast strains lacking the Ca(2+)-ATPase Pmr1p are unable to maintain an adequate level of Ca(2+) within the Golgi apparatus. It is thought that this compartmental store depletion induces a signal that causes an increased rate of Ca(2+) uptake and accumulation in a manner similar to the capacitative Ca(2+) entry (CCE) response in non-excitable mammalian cells. To explore this model further, we examined cellular Ca(2+) uptake and accumulation in a pmr1Delta strain grown in the presence of a reduced level of divalent cations. We found that the level of Ca(2+) uptake and accumulation in a pmr1Delta strain increased as the concentration of divalent cations in the growth medium decreased. These results are inconsistent with a model in which cellular Ca(2+) uptake and accumulation are determined solely by the depletion of Ca(2+) in an intracellular compartment. Instead, our results suggest that a second regulatory mechanism couples cellular Ca(2+) uptake to the availability of Ca(2+) in the extracellular environment. Furthermore, we found that various conditions that increase the level of cytosolic Ca(2+) correlate with vacuolar fragmentation in wild-type (WT), pmr1Delta and pmr1Delta/pmc1Delta yeast strains. This suggests that vacuolar fragmentation might function as a normal physiological response to Ca(2+) stress that increases the vacuolar surface/volume ratio, thereby maximizing the sequestration of this important signaling molecule.
The records of 22 children with parvovirus B19-induced aplastic crisis were reviewed. The group consisted of 16 children with sickle cell hemoglobinopathies and 6 with hereditary spherocytosis. Children presented to the hospital 0.5 to 8 days (mean, 2.4 days) after the onset of symptoms. The children with sickle-cell disease presented earlier (mean, 1.4 days) than did children with hereditary spherocytosis (mean, 5 days; P = 0.02. Fever was the most common symptom, occurring in 73% of children. Rash did not occur in either group. Reticulocyte counts began to rise 1 week after onset of illness associated with a rise in parvovirus B19-specific IgG antibody. These data suggest that parvovirus B19 infection in children with sickle-cell hemoglobinopathies and heredity spherocytosis differs from infection in normal children.
Gap junctions are formed by a polygenic family of more than 20 different connexin proteins. They mediate intercellular communication via the direct exchange of ions, metabolites and secondary messengers, thus controlling and coordinating cellular activities. Mutations in five gap junction genes, including GJB2 (Cx26), GJB3 (Cx31), GJB4 (Cx30.3), GJB6 (Cx30) and GJA1 (Cx43) are known to cause inherited hearing loss and/or disorders of the skin and its appendages, often giving rise to overlapping phenotypes. In this study we present a patient with hidrotic ectodermal dysplasia, who had abortive features of oculo-dento-digital dysplasia, extensive hyperkeratosis of the skin. The patient harbored a novel sporadic mutation (V41L) in GJA1 (Cx43) as well as a heterozygous coding variant (R127H) of GJB2 (Cx26). Our findings suggest that GJA1 mutations can produce variable clinical phenotypes on the background of sequence variants in other connexins.