ABSTRACT
Nonspecific X-linked mental retardation is a nonprogressive, genetically heterogeneous condition that affects cognitive function in the absence of other distinctive clinical manifestations. We report here linkage data on a large Pakistani family affected by a form of X-linked nonspecific mental retardation. X chromosome genotyping of family members and linkage analysis allowed the identification of a new disease locus, MRX53. The defined critical region spans approximately 15 cM between DXS1210 and DXS1047 in Xq22.2-26. A LOD score value of 3.34 at no recombination was obtained with markers DXS1072 and DXS8081.
Subject(s)
Intellectual Disability/genetics , X Chromosome/genetics , Chromosome Mapping , DNA/genetics , Family Health , Female , Genetic Linkage , Genotype , Humans , Intellectual Disability/pathology , Lod Score , Male , Microsatellite Repeats , Pakistan , PedigreeABSTRACT
A new syndromic form of X-linked mental retardation associated to obesity, MRXS7, has been localised to Xp11.3-Xq23 in a large Pakistani family. The ten affected males show clinical manifestations of mental retardation, obesity and hypogonadism. The family was genotyped by a set of microsatellite markers spaced at approximately 10 cM intervals on the X chromosome. Linkage to five adjacent microsatellite markers, mapping in the pericentromeric area, was established and a maximum two-point lod score of 3.86 was reached at zero recombination with marker DXS1106. Reduced recombination events around the centromere prevented precise mapping of the gene.
Subject(s)
Chromosome Mapping , Genetic Linkage/genetics , Intellectual Disability/genetics , Obesity/genetics , X Chromosome/genetics , Adolescent , Adult , Female , Humans , Lod Score , Male , Middle Aged , Pedigree , SyndromeABSTRACT
D-myo-Inositol 1,4,5-triphosphate (IP3) is a key second messenger in many cells, including macrophages, T and B cells, and neutrophils, in which it regulates free intracellular calcium ion levels. In human polymorphonuclear leukocytes the rise of intracellular [Ca2+] is the signal that activates a number of functions such as adherence, aggregation, chemotaxis, and degranulation, which are typically depressed in newborn infants. IP3 generation can be stimulated by N-formyl-methionyl-leucylphenylalanine (fMLP) tripeptide, which mimics the naturally occurring bacterial oligopeptides. In this study both neonatal and adult polymorphonuclear leukocytes were stimulated by fMLP (1 x 10(-6) M) and the levels of IP3 were assayed by a specific radiometric method. The time course of IP3 generation was studied for up to 60 s in a total of 10 samples. The response appeared reduced in cord blood samples. To confirm this observation, we extended our study to a larger number of samples, quantitating [IP3] at the time peak of 10 s. As expected IP3 generation was significantly (F test, p < 0.0001, n = 39) lower in newborns than in adults (means +/- SD = 0.64 +/- 0.25; 1.26 +/- 0.36, ng/10(6) cells, respectively). Besides soluble stimulus, neutrophils were treated with a particulate stimulus, namely serum-treated zymosan, which is also able to stimulate IP3 synthesis from polymorphonuclear leukocytes. Serum-treated zymosan produced a prolonged elevation in the level of IP3, reaching a plateau within 120 s in both cord blood and in control samples.(ABSTRACT TRUNCATED AT 250 WORDS)
