Association between serotonin 2C receptor gene (HTR2C) polymorphisms and psychopathological symptoms in children and adolescents

Serotonin 2C receptors (5HT2C) are involved in serotonin-driven dynamic equilibrium adjustments responsible for homeostatic stability in brain structures that modulate behavior and emotions. Single nucleotide polymorphisms (SNPs) from the serotonin 2C receptor gene (HTR2C) have been associated with several neurological and mental disorders, including abnormalities in cognitive and emotional processes. The aim of this study was to evaluate the association between the rs6318 SNP of the HTR2C gene and behavioral characteristics exhibited by children and adolescents based on the Child Behavior Checklist (CBCL/6-18) inventory. Eighty-five psychiatric outpatients between 8 and 18 years of age underwent genotyping of the rs6318 SNP. The CBCL/6-18 scale was administered to their caregivers. The chi-squared test was used to assess differences in the frequency of C and G alleles of the rs6318 SNP relative to the grouped CBCL/6-18 scores; significance level was 5%. The presence of the G allele of rs6318 was found to be associated with characteristics of aggressive behavior and social problems, and aggressive behavior was found to be associated with heterozygosis in females. These findings contribute to the identification of mental and behavioral phenotypes associated with gene expression.

The novel p.E89K mutation in the SRY gene inhibits DNA binding and causes the 46,XY disorder of sex development

Male sex determination in humans is controlled by the SRY gene, which encodes a transcriptional regulator containing a conserved high mobility group box domain (HMG-box) required for DNA binding. Mutations in the SRY HMG-box affect protein function, causing sex reversal phenotypes. In the present study, we describe a 19-year-old female presenting 46,XY karyotype with hypogonadism and primary amenorrhea that led to the diagnosis of 46,XY complete gonadal dysgenesis. The novel p.E89K missense mutation in the SRY HMG-box was identified as a de novo mutation. Electrophoretic mobility shift assays showed that p.E89K almost completely abolished SRY DNA-binding activity, suggesting that it is the cause of SRY function impairment. In addition, we report the occurrence of the p.G95R mutation in a 46,XY female with complete gonadal dysgenesis. According to the three-dimensional structure of the human SRY HMG-box, the substitution of the conserved glutamic acid residue by the basic lysine at position 89 introduces an extra positive charge adjacent to and between the positively charged residues R86 and K92, important for stabilizing the HMG-box helix 2 with DNA. Thus, we propose that an electrostatic repulsion caused by the proximity of these positive charges could destabilize the tip of helix 2, abrogating DNA interaction.

Comparison of bone quantity by ultrasound measurements of phalanges between white and black children living in Paraná, Brazil, with Europeans

The objective of this study was to determine bone quantity by ultrasound measurements of the proximal finger phalanges (AD-SoS = amplitude-dependent speed of sound) of healthy Brazilian schoolchildren living in Paraná, Brazil and to compare these values with European populations. The sample was composed of 1356 Brazilian schoolchildren of both genders (660 males, 696 females), aged 6 to 11 years, divided into white (840) and black (516) groups and compared to age- and gender-matched Europeans. AD-SoS of the schoolchildren increased significantly with age for both genders. Significantly higher AD-SoS values were observed for the white children (1916 ± 58) compared to their black counterparts (1898 ± 72) and for the female gender (1920 ± 61) compared to the male gender (1898 ± 66). Overall, the AD-SoS outcomes for females were similar to those of European studies. However, the AD-SoS of the Brazilian schoolchildren of both genders and skin colors was lower than that reported for children in Poland. AD-SoS outcomes for Brazilian schoolboys were similar to those obtained in Italian studies and were lower than those of the Spanish children. In conclusion, Brazilian schoolchildren of both genders and skin colors showed lower bone quantities than Polish children and Spanish males, and levels similar to Italian children and Spanish females.

The influence of parental origin of X chromosome genes on the stature of patients with 45 X Turner syndrome

Thirty-seven 45 X Turner syndrome patients with confirmed peripheral blood lymphocyte karyotype were initially selected to determine the origin of the retained X chromosome and to correlate it with their parents’ stature. Blood samples were available in 25 families. The parental origin of the X chromosome was determined in 24 informativefamilies through the analysis of the exon 1 - CAG repeat variation of the androgen receptor gene. In 70.8% of the cases, the retained X chromosome was maternal in origin and 29.2% was paternal. When we classified the patients according to maternal (Xm) or paternal (Xp) X chromosome, there was a positive correlation between patients’ and maternal heights only in the Xm group. There was no correlation with paternal height in either group, and a significant correlation with target height was only observed in the Xm group. In conclusion, maternal height is the best variable correlating with the height of 45 X Turner syndrome patients who retain the maternal X chromosome, suggesting a strong influence of genes located on the maternal X chromosome on stature.

Female counterpart of shawl scrotum in aarskog-scott syndrome

Aarskog-Scott syndrome (ASS) is an X-linked disorder characterized by facial, skeletal and genital anomalies, including penoscrotal transposition in males. We report on a girl from a family with ASS who exhibits a transposition of the clitoris.

Mutations in SRY and WT1 genes required for gonadal development are not responsible for XY partial gonadal dysgenesis

The WT1 transcription factor regulates SRY expression during the initial steps of the sex determination process in humans, activating a gene cascade leading to testis differentiation. In addition to causing Wilms' tumor, mutations in WT1 are often responsible for urogenital defects in men, while SRY mutations are mainly related to 46,XY pure gonadal dysgenesis. In order to evaluate their role in abnormal testicular organogenesis, we screened for SRY and WT1 gene mutations in 10 children with XY partial gonadal dysgenesis, 2 of whom with a history of Wilms' tumor. The open reading frame and 360 bp of the 5' flanking sequence of the SRY gene, and the ten exons and intron boundaries of the WT1 gene were amplified by PCR of genomic DNA. Single-strand conformation polymorphism was initially used for WT1 mutation screening. Since shifts in fragment migration were only observed for intron/exon 4, the ten WT1 exons from all patients were sequenced manually. No mutations were detected in the SRY 5' untranslated region or within SRY open-reading frame sequences. WT1 sequencing revealed one missense mutation (D396N) in the ninth exon of a patient who also had Wilms' tumor. In addition, two silent point mutations were found in the first exon including one described here for the first time. Some non-coding sequence variations were detected, representing one new (IVS4+85A>G) and two already described (-7ATG T>G, IVS9-49 T>C) single nucleotide polymorphisms. Therefore, mutations in two major genes required for gonadal development, SRY and WT1, are not responsible for XY partial gonadal dysgenesis.

Molecular analysis of CYP21 and C4 genes in Brazilian families with the classical form of steroid 21-hydroxylase deficiency

The most common enzymatic defect of steroid synthesis is deficiency of the adrenal steroid 21-hydroxylase. Inhibition of the formation of cortisol results in an increased pituitary release of ACTH which in turn drives the adrenal cortex to overproduce androgens. This hormonal setting affects the development of genetic females by misdirecting the differentiation of external genitalia towards the male type. Since the isolation of the gene encoding 21-hydroxylase enzyme in 1984, gene deletions, large gene conversions, and microconversions have been reported to be responsible for the disease. In this paper, we report a study of this genetic defect in 22 families with one or more affected offspring diagnosed as having the classical form of congenital adrenal hyperplasia. The DNA from 30 patients was analyzed with three restriction enzymes. Hybridization with a 21-hydroxylase cDNA probe and the 5' end of a C4 genomic probe disclosed gene deletion in 7.3 percent (3/41) of the disease-related chromosomes. The rate of large gene conversion was 17.1 percent (7/41), and no abnormality in the hybridization pattern was observed in 75.6 percent (31/41) of the disease alleles. Densitometry of the autoradiographs was used to determine the ratio of the copy-number of the 2 1-hydroxylase gene (CYP21B) to the copy-number of its pseudogene (CYP21A). Differences in phenotype, the low frequency of gene deletion, and the high frequency of gene conversion compared with other studies in different populations indicated that 21-hydroxylase deficiency in the Brazilian population may involve different molecular mutations.