Noonan-like syndrome with loose anagen hair (NSLH MIM 607721) is associated to mutations in PTPN11, RAF1, BRAF and SHOC2 genes.

Here, we report behavioral phenotype of a child suspected to have NSLH.

A 2-years-old Tunisian child harboring severe pulmonic valvular stenosis was referred to our genetic counselling for genetic assessment. Medical dysmorphology, cytogenetic analysis as well as genetic exploration of RAS-MAPK pathway genes were conducted.

The child had short stature and ectodermal features including ichthyotic skin and thin-soft nails. He has specific hair appearance associated to NS features. In fact, he had a small nasal tip, thick lips and sticking-out rotated ears. He harbored typical nasal voice and loose anagen hair with ungrowing thin hair, sparse and pale scalp hair and eyebrows. He showed cognitive deficits with mental retardation and hyperactive behavior. Considered as having NSLH, cytogenetic analysis revealed a 46,XY formula, but molecular screening of PTPN11, RAF1, BRAF, RIT1 and SHOC2 genes was negative.

Mutations within the RAS‐MAPK signaling pathway affect neurophysiologic activity in brain regions underlying attention and executive functions. Children with rasopathies demonstrated higher rates of attention deficit-hyperactivity (ADHD) and autism spectrum disorders. However, no studies have examined specifically the aspects of behavioral attention in the various types of Rasopathies. A recent study demonstrated that ADHD seems to be higher in children with NSLH and SHOC2 mutation, which is the case of our patient. We suggest that assessment of inattentive and hyperactivity symptoms in children should consider Rasopathies with specific molecular screening.

No significant relationships.

Patients with attention deficit-hyperactivity disorder (ADHD) exhibit difficulties in multiple attentional functions. Although high heritability rates suggest a strong genetic impact, aetiological pathways from genes and environmental factors to the ADHD phenotype are not well understood. Tracking the time course of deviant task processing using event-related electrophysiological brain activity should characterize the impact of familiality on the sequence of cognitive functions from preparation to response control in ADHD.

Preparation and response control were assessed using behavioural and electrophysiological parameters of two versions of a cued continuous performance test with varying attentional load in boys with ADHD combined type (n = 97), their non-affected siblings (n = 27) and control children without a family history of ADHD (n = 43).

Children with ADHD and non-affected siblings showed more variable performance and made more omission errors than controls. The preparatory Cue-P3 and contingent negative variation (CNV) following cues were reduced in both ADHD children and their non-affected siblings compared with controls. The NoGo-P3 was diminished in ADHD compared with controls whilst non-affected siblings were located intermediate but did not differ from both other groups. No clear familiality effects were found for the Go-P3. Better task performance was further associated with higher CNV and P3 amplitudes.

Impairments in performance and electrophysiological parameters reflecting preparatory processes and to some extend also for inhibitory response control, especially under high attentional load, appeared to be familially driven in ADHD and may thus constitute functionally relevant endophenotypes for the disorder.