The presence of an additional X or Y chromosome (sex chromosome trisomies, SCT) is associated with an increased risk for neurodevelopmental difficulties, including socio-emotional problems, across the life span. Studying emotion regulation in young children with SCT could signal deviations in emotional development that serve as risk markers to guide clinical care. This study explored the presence and variety of emotion regulation strategies in 75 SCT children and 81 population-based controls, aged 1–7 years, during a frustration-inducing event in which physiological (heart rate) and observational data (behavioral responses) were collected. Children with SCT were equally physiologically aroused by the event as compared to controls. However, they showed more emotion regulation difficulties in terms of behavior compared to controls that were not explicable in terms of differences in general intellectual functioning. Specifically, they had a more limited range of behavioral alternatives and tended to rely longer on inefficient strategies with increasing age. The field of practice should be made aware of these early risk findings regarding emotion regulation in SCT, which may potentially lay the foundation for later socio-emotional problems, given the significant impact of emotion regulation on child and adult mental health outcomes. The current results may help to design tailored interventions to reduce the impact of the additional sex chromosome on adaptive functioning, psychopathology, and quality of life.

Conditions related to cardiometabolic disease, including metabolic syndrome and type 2 diabetes, are common among men with Klinefelter syndrome (KS). The molecular mechanisms underlying this aberrant metabolism in KS are largely unknown, although there is an assumption that chronic testosterone deficiency plays a role. This cross-sectional study compared plasma metabolites in 31 pubertal adolescent males with KS to 32 controls of similar age (14 ± 2 years), pubertal stage, and body mass index z-score of 0.1 ± 1.2 and then between testosterone-treated (n = 16) and untreated males with KS. The plasma metabolome in males with KS was distinctly different from that in controls, with 22% of measured metabolites having a differential abundance and seven metabolites nearly completely separating KS from controls (area under the curve > 0.9, P < 0.0001). Multiple saturated free fatty acids were higher in KS, while mono- and polyunsaturated fatty acids were lower, and the top significantly enriched pathway was mitochondrial β-oxidation of long-chain saturated fatty acids (enrichment ratio 16, P < 0.0001). In contrast, there were no observed differences in metabolite concentrations between testosterone-treated and untreated individuals with KS. In conclusion, the plasma metabolome profile in adolescent males with KS is distinctly different from that in males without KS independent of age, obesity, pubertal development, or testosterone treatment status and is suggestive of differences in mitochondrial β-oxidation.

The 3rd International Workshop on Klinefelter Syndrome, Trisomy X, and 47,XYY syndrome was held in Leiden, the Netherlands, on September 12–14, 2022.

Here, we review new data presented at the workshop and discuss scientific and clinical trajectories. We focus on shortcomings in knowledge and therefore point out future areas for research.

We focus on the genetics and genomics of supernumerary sex chromosome syndromes with new data being presented. Most knowledge centre specifically on Klinefelter syndrome, where aspects on testosterone deficiency and the relation to bone, muscle and fat were discussed, as was infertility and the treatment thereof. Both trisomy X and 47,XYY syndrome are frequently affected by infertility.

Transitioning of males with Klinefelter syndrome was addressed, as this seemingly simple process in practise is often difficult.

It is now realized that neurocognitive changes are pervasive in all supernumerary sex chromosome syndromes, which were extensively discussed. New intervention projects were also described, and exciting new data concerning these were presented.

Advocacy organizations were present, describing the enormous burden carried by parents when having to explain their child’s specific syndrome to most professionals whenever in contact with health care and education systems. It was also pointed out that most countries do not have health care systems that diagnose patients with supernumerary sex chromosome syndromes, thus pinpointing a clear deficiency in the current genetic testing and care models.

At the end of the workshop, a roadmap towards the development of new international clinical care guidelines for Klinefelter syndrome was decided.