Educational status, testosterone replacement, and intelligence outcomes in Klinefelter syndrome.

Most male hypergonadotropic hypogonadism associated with infertility can be attributed to a single genetic condition such as Klinefelter syndrome (KS). This disease's wide phenotypic variability is frequently associated with mosaic 47,XXY lineages and testosterone replacement. Early diagnosis and treatment have been associated with better cognitive and intellectual outcomes, but the scope of this influence requires further investigation. Objective: This study aimed to investigate the intelligence profile of a cohort of patients with KS, considering the influence of educational level and clinical variables. Methods: Twenty-nine (9-65 years) individuals were submitted to the measures of intelligence quotient (IQ) (Wechsler's Scales) and adaptive behavior (Vineland-II). Linear regression analysis included the participants' educational level and clinical variables (i.e., comorbidities and use of testosterone) as predictors and intellectual performance and adaptive behavior as outcomes. Results: Scores varied from intellectual deficiency to average ranges (82.5+15.8). There were significant differences between adult's and children's IQ and between verbal and nonverbal indexes. The level of education predicted both IQ and adaptive behavior. Testosterone replacement therapy and absence of seizures predicted only adaptive behavior. Conclusions: The level of education and hormonal therapy can be selectively implicated in the intellectual variability in KS.

A maioria dos casos de hipogonadismo hipergonadotrófico masculino associado à infertilidade pode ser atribuída a uma única condição genética ­ a síndrome de Klinefelter (KS). A ampla variabilidade fenotípica dessa doença está frequentemente associada a linhagens de mosaico 47,XXY e também à reposição de testosterona. O diagnóstico e o tratamento precoces têm sido associados a melhores desfechos em termos de cognição e inteligência, mas o escopo dessa influência requer maior investigação. Objetivo: Este estudo investigou o perfil de inteligência de uma coorte de pacientes com KS, considerando a influência do nível educacional e das variáveis clínicas. Métodos: Vinte e nove indivíduos (9­65 anos) foram submetidos a medidas de quociente de inteligência (escalas Wechsler) e de comportamento adaptativo (escala Vineland-II). A análise de regressão linear considerou o nível educacional dos participantes e variáveis clínicas (comorbidades, uso de testosterona) como preditores e desempenho intelectual e comportamento adaptativo como desfechos. Resultados: Os resultados mostraram escores que variaram de deficiência intelectual à faixa média (82,5+15,8). Houve diferenças significativas entre os quocientes de inteligência de adultos e crianças e entre os índices verbais e não verbais. O nível educacional influenciou tanto o quociente de inteligência quanto o comportamento adaptativo. A terapia de reposição de testosterona e a ausência de convulsões influenciaram apenas o comportamento adaptativo. . Conclusões: Sendo assim, nível educacional e terapia hormonal podem estar seletivamente implicados na variabilidade intelectual na KS.

Intelligence Quotient Variability in Klinefelter Syndrome Is Associated With GTPBP6 Expression Under Regulation of X-Chromosome Inactivation Pattern.

Klinefelter syndrome (KS) displays a broad dysmorphological, endocrinological, and neuropsychological clinical spectrum. We hypothesized that the neurocognitive dysfunction present in KS relies on an imbalance in X-chromosome gene expression. Thus, the X-chromosome inactivation (XCI) pattern and neurocognitive X-linked gene expression were tested and correlated with intelligence quotient (IQ) scores. We evaluated 11 KS patients by (a) IQ assessment, (b) analyzing the XCI patterns using both HUMARA and ZDHHC15 gene assays, and (c) blood RT-qPCR to investigate seven X-linked genes related to neurocognitive development (GTPBP6, EIF2S3, ITM2A, HUWE1, KDM5C, GDI1, and VAMP7) and XIST in comparison with 14 (male and female) controls. Considering IQ 80 as the standard minimum reference, we verified that the variability in IQ scores in KS patients seemed to be associated with the XCI pattern. Seven individuals in the KS group presented a random X-inactivation (RXI) and lower average IQ than the four individuals who presented a skewed X-inactivation (SXI) pattern. The evaluation of gene expression showed higher GTPBP6 expression in KS patients with RXI than in controls (p = 0.0059). Interestingly, the expression of GTPBP6 in KS patients with SXI did not differ from that observed in controls. Therefore, our data suggest for the first time that GTPBP6 expression is negatively associated with full-scale IQ under the regulation of the type of XCI pattern. The SXI pattern may regulate GTPBP6 expression, thereby dampening the impairment in cognitive performance and playing a role in intelligence variability in individuals with KS, which warrants further mechanistic investigations.