Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adhesion molecules play a major role in the recruitment of neutrophils to the site of inflammation. Currently, two congenital hereditary Leukocyte Adhesion Deficiency (LAD) syndromes are recognized. LAD I is due to the absence of the beta subunit of the integrin molecule, while LAD II is caused by a deficiency of Sialy1 Lewis X, the neutrophil ligand for selectins. Clinically, both syndromes are characterized by recurrent bacterial infections, more severe in LAD I. Developmental abnormalities (growth and mental retardation) constitute a prominent feature of LAD II and may be attributed to a general defect found in fucose metabolism in LAD II. Neutrophil motility was found to be defective in both syndromes. Using activated umbilical endothelial cells, we showed that LAD I neutrophil do not bind to cells expressing ICAM-1, while LAD II cells do not bind to endothelial cells expressing E- or P-selectin. Skin window technique showed a marked decrease in margination in both syndromes. Using intravital microscopy we were able to show that the basic defect in LAD II is in the "rolling" phase, while in LAD I, firm adhesion and transmigration are defective. Studies of these two rare conditions emphasized the important in vivo roles of adhesion molecules in host defense mechanism.
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PMID:Adhesion molecule deficiencies and their clinical significance. 782 63

Rambam-Hasharon syndrome (RHS) is a newly recognized autosomal recessive inborn error in fucose metabolism. Mental retardation, short stature, coarse facies, and recurrent infections are the main clinical findings. Several fucosilated proteoglycans are deficient in these patients. Leukocyte adhesion deficiency type 2 is associated with lack of the membrane glycoprotein sialyl-Lewisx (CD15s). In the red blood cells (RBCs), lack of the membrane glycoprotein H is manifested as a Bombay (Oh) blood type. Two consecutive pregnancies it risk for RHS were monitored during mid-trimester by cordocentesis. One fetus expressed H substance and her blood phenotype was O Rh+. The second fetus, a female, was 2 weeks smaller than expected by dates and had the Bombay blood type. The placenta of the affected fetus was small and irregular. This is the first prenatal diagnosis of this syndrome and the first case found in a female. The documentation of the syndrome in patients of both sexes and the parental consanguinity support an autosomal recessive inheritance. Two apparent recombinations between fucosyl-transferase 1 (FUT1, the H gene) and fucosyl-transferase 2 (secretor) are suggestive of non-allelic heterogeneity. We believe that the Bombay phenotype in this family is caused by a mutated gene, other than FUT1, which is causing multiple deficiencies of fucosilated proteoglycans.
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PMID:Prenatal diagnosis of Rambam-Hasharon syndrome. 871 Jul 83

Leukocyte adhesion deficiency (LAD) type II is the second human disorder identified which involves the adhesion cascade. While in LAD I the integrin family is defective, in LAD II the selectin system is involved. The syndrome has been described in only five patients and is transmitted as an autosomal recessive trait. The infectious episodes and the severity are much milder than those observed in LAD I, and the only persistent clinical symptom is chronic severe periodontitis. Delay separation of the umbilical cord, which is a hallmark for LAD I, was not observed in any of the LAD II patients. The exact defect in the system is absence of the SLeX, which is an important ligand for the selectin on the leukocyte lead ing to a profound defect in leukocyte rolling, the first step in the adhesion cascade. This causes a marked decrease in chemotaxis accompanied by pronounced neutrophilia. Apart from the leukocyte defect, these patients suffer from severe growth and mental retardation and exhibit the rare Bombay blood group type. The primary defect in the syndrome is in fucose metabolism, with the absence of all fucosylated glycans on cell surface membranes. Recently, it is was found that the defect is in a specific transporter of GDP fucose into the Golgi apparatus, and thus no fucosylation process takes place, and no surface expression can be detected. The exact genetic defect in the transporter is still unknown. Four of the patients were of Arabic origin while the fifth was of Turkish origin. It seems that the primary defect is somewhat different and, therefore, fucose administration was effective in the Turkish child, but did not show any beneficial results in the patients of Arabic origin.
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PMID:Leukocyte adhesion deficiency II-from A to almost Z. 1121 99

Leukocyte adhesion deficiency type II is an autosomal recessive syndrome characterized by generalized reduction of L-fucose in glycoconjugates; the specific molecular defect is still undefined. The most important clinical symptoms include severe growth and mental retardation and severe immunodeficiency. Patients from two ethnic groups have been reported, i.e. Arab and Turkish. We have observed that GDP-L-fucose transport into Golgi vesicles was specifically impaired in an Arab patient, with a significant reduction of the V:(max) but no significant differences in the K:(m) from control and parents. GDP-L-fucose transport showed simple saturation kinetics in all samples. Transport of UDP-galactose, UDP-N:-acetylglucosamine, and CMP-sialic acid was comparable into vesicles from the Arab patient, parents, and control. These kinetic parameters probably account for the failure to obtain any clinical and biochemical response to fucose therapy in Arab patients. This contrasts both with the distinctive kinetic properties of GDP-L-fucose transport and with the success of fucose therapy, which have been recently reported in one patient of Turkish origin. Accordingly, the biochemical properties of GDP-L-fucose transport into the Golgi are consistent with different variants of leukocyte adhesion deficiency type II that are probably the result of different molecular defects.
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PMID:Impairment of the Golgi GDP-L-fucose transport and unresponsiveness to fucose replacement therapy in LAD II patients. 1126 38

Leukocyte adhesion deficiency type 2 (LADII) is characterized by defective selectin ligand formation, recurrent infection, and mental retardation. This rare syndrome has only been described in 2 kindreds of Middle Eastern descent who have differentially responded to exogenous fucose treatment. The molecular defect was recently ascribed to single and distinct missense mutations in a putative Golgi guanosine diphosphate (GDP)-fucose transporter. Here, we describe a patient of Brazilian origin with features of LADII. Sequencing of the GDP-fucose transporter revealed a novel single nucleotide deletion producing a shift in the open-reading frame and severe truncation of the polypeptide. Overexpression of the mutant protein in the patient's fibroblasts did not rescue fucosylation, suggesting that the deletion ablated the activity of the transporter. Administration of oral L-fucose to the patient produced molecular and clinical responses, as measured by the appearance of selectin ligands, normalization of neutrophil counts, and prevention of infectious recurrence. The lower neutrophil counts paralleled improved neutrophil interactions with activated endothelium in cremasteric venules of nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice. However, fucose supplementation induced autoimmune neutropenia and the appearance of H antigen on erythrocytes, albeit without evidence of intravascular hemolysis. The robust response to fucose despite a severely truncated transporter suggests alternative means to transport GDP-fucose into the Golgi complex.
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PMID:Insights into leukocyte adhesion deficiency type 2 from a novel mutation in the GDP-fucose transporter gene. 1240 89

Leukocyte adhesion deficiency type II (LAD II) is a rare, autosomal, recessive inherited immunodeficiency disease that induces frequent and recurrent infections, persistent leukocytosis, severe mental and growth retardation, and impaired wound healing. The Bombay blood group is a rare blood group phenotype that is characterised by the deficiency of H, A, and B antigens on the surface of red cells. LAD II and the Bombay blood group are always seen together, because both of them are associated with a global defect in the common pathway of fucose metabolism. Here we report the case of an 11-year-old boy with LAD II, who presented with the Bombay blood group. Agglutination with strength of 4+ was detected in all cross-matching due to erythrocyte transfusions for our patient. Therefore, the Bombay blood group was incidentally determined due to deficient expression of the CD15 adhesion molecules on the surface of the leukocytes according to the results of flow cytometry. Upon detecting the Bombay blood type, LAD II was then diagnosed as a result of flow cytometry and the clinical findings of mental retardation and history of recurrent infections such as abscesses.
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PMID:Late diagnosis of leukocyte adhesion deficiency type II and Bombay blood type in a child: a rare case report. 3153 Sep 91