Fragile X (fra(X)) males with a standardized IQ score of 70 or higher represent a high functioning (HF) or nonretarded fra(X) male group. This group, which does not include nonpenetrant males, has received little research attention to date. Of 221 fra(X) males who had been evaluated through The Children's Hospital in Denver since 1981 and had completed cognitive or developmental testing, 29 (13%) were high functioning by the above definition. We found that HF males on the whole had a lower cytogenetic score and were younger than retarded fra(X) males, but there was no difference between these two groups in the number of typical fra(X) physical manifestations present. FMR-1 DNA testing was performed on 134 fra(X) males and methylation status was determined for 51 of these. A greater percentage of HF males had a mosaic pattern or an incompletely methylated full mutation than did retarded males. A unique DNA pattern, an unmethylated fully expanded mutation, was discovered in 3 of the highest functioning fra(X) males. Protein studies performed on 2 of these males demonstrated the presence of FMR-1 protein, albeit at lower levels than normal. FMR-1 protein was not present in retarded fra(X) males. Significant FMR-1 protein expression may be responsible for higher cognitive functioning in the 2 males with unmethylated fully expanded mutations compared to retarded fra(X) males.

The paper describes synthesis of 3-amino-cyclobutane-1-carboxylic acid and its resolution into diastereoisomers. Preparations of cerebral 4-aminobutyrate: 2-oxoglutarate aminotransferase were capable of utilizing both diastereoisomers for transamination. In the uptake of (2,3-H3)-4-aminobutyric acid by slices of rat cerebral tissue the two isomers fUllction as simple competitive inhibitors. The inhibitary potency of the uptake and the utilization in transamination of the cis isomer was higher than that of the trans isomer. This reflects specific steric pre-requisites for the two processes.

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2-Oxoglutaric acid reacts with 3-methyl-2-benzothiazoline hydrazone in acid solutions in the presence of FeCl3 to give a stady yellow colour. The method enables the substance to be determined in concentrations as low as 15 μmol l-1 with an accuracy of about 10%. The analysis can be performed in the presence of some additional natural or synthetic 2-oxo acids. The applicability of the method was tested in the determination of the activity of some enzymes involved in the metabolism of 2-oxoglutaric acid. Glutamic acid can be determined after its prior nonenzymatic transamination. A number of 2-oxo acids including 2-oxoglutaric acid can be determined photometrically with a high sensitivity by reaction with 3-methyl-2-benzothiazolinone hydrazone in conditions favouring the formation of blue tetra-aza-pentamethinecyanine dyes. The molar absorptivities largely lay within the region of (2-4.5) . 104 l mol-1cm-1.