Reports of Biochemistry

Background: Transforming growth factor-β1 (TGF-β1) has been found to play a crucial role in early central nervous system development. Several studies have illustrated decreased TGF-β1 levels in sera and brains of autistic children. Two point mutations in the TGF-β1 signal peptide at 869T/C and 915G/C have been reported to influence TGF-β1 expression. The aim of the present study was to investigate the correlation of TGF-β1 polymorphisms and their haplotypes with autism.

Methods: This study was performed on 39 autistic patients and 35 age- and sex-matched normal controls in an Iranian population, using the sequence specific primed-polymerase chain reaction (PCR-SSP) technique. Patients were divided into mild-to-moderate and severe groups according to the childhood autism rating scale.

Results: No significant differences were observed for allele, genotype, or haplotype frequencies between the autistics and controls. Only a slight difference was observed in GC25 between the controls and all children with autism.

Conclusion: Thus, these results indicate that the polymorphisms in TGF-β1 gene may not play an important role in the development of autism.

Background: Urinary organic acids are water-soluble intermediates and end products of the metabolism of amino acids, carbohydrates, lipids, and a number of other metabolic processes. In the hereditary diseases known as organic acidurias, an enzyme or co-factor defect in a metabolic pathway leads to the accumulation and increased excretion of one or more of these acidic metabolites. Gas chromatography is the most commonly-used technology to separate and identify these metabolites. In this report the analytical conditions for the determination of methylmalonic acid using a gas chromatography/flame ionization detector (GC-FID) are studied with the aim to establish a method to analyze organic acids in human urine.

Methods: Studies included the GC-FID method development, the conditions of the derivatization (trimethylsilylation) reaction, and the stability of the methylmalonic acid standard solution and trimethylsilyl derivatives during storage. Also, a systematic comparison between GC-FID and gas chromatography/mass spectrometry (GC-MS) was performed.

Results: The highest resolution and sensitivity were obtained at 60 oC with a 30 min reaction time. Standard solutions and derivatized samples were stable for 7 days at 4-8 ^oC. Relative standard deviations of within-day and day-to-day assay results were less than 5%. Methylmalonic acid was detected in thirty human urine samples by the proposed GC-FID, and the results were compared with gold standard technique GC-MS. The correlation coefficient between GC-MS and GC-FID was obtained with R²= 0.997.

Conclusions: The developed method was applied to the quantitative analysis of methylmalonic acid in urine from hospitalized children with methylmalonic acidemia. With this method we aim to support pediatric clinics in Iran and assist in clinical diagnostics.

Background: Disorders of sex development (DSDs) belong to uncommon pathologies and result from abnormalities during gonadal determination and differentiation. Various gene mutations involved in gonadal determination and differentiation have been associated with gonadal dysgenesis. Despite advances in exploration of genes and mechanisms involved in sex disorders, most children with severe 46,XY DSDs have no definitive etiological diagnoses; therefore, the possibility that other genes or loci might play important roles in these disorders needs to be explored.

Methods: Patients (37) clinically suspicious for 46,XY gonadal dysgenesis (46,XY GD) of unknown etiology were studied. SRY, encoding the sex-determining region Y protein, NR5A1, encoding a transcription factor called steroidogenic factor 1, and DHH, encoding the desert hedgehog protein, were directly sequenced. Multiplex ligation-dependent probe amplification (MLPA) was used to detect deletions in NR0B1, encoding the DAX1 protein, and WNT4, encoding the WNT4 protein, and real-time PCR (qPCR) confirmed the MLPA data. Other potential loci have been investigated in the complete genome using Array-Comparative Genomic Hybridization, (Array CGH).

Results: The SRY deletion was found in five patients. One each of previously described NR5A1, DHH, and AR (androgen receptor) allelic variants were identified. A pathogenic c.2522G>A AR mutation was found in two affected brothers. A heterozygous partial deletion was found in NR5A1 and heterozygous partial duplications were found in WNT4. These deletions and duplications (del/dup) were confirmed by qPCR. The Array CGH result demonstrated one partial deletion in SOX2-OT, which encodes a member of the SOX family of transcription factors, and the exact region of the rearrangements.

Conclusions: According to our study, del/dup mutations could be checked prior to point mutations, SOX2-OT has a potential role in gonadal dysgenesis, and Array CGH has a prominent role in gonadal dysgenesis diagnosis.