Sex‐specific manifestation of genetic risk for attention deficit hyperactivity disorder in the general population

Background

Attention deficit hyperactivity disorder (ADHD) is more commonly diagnosed in males than in females. A growing body of research suggests that females with ADHD might be underdiagnosed or receive alternative diagnoses, such as anxiety or depression. Other lines of reasoning suggest that females might be protected from developing ADHD, requiring a higher burden of genetic risk to manifest the disorder.

Methods

We tested these two hypotheses, using common variant genetic data from two population‐based cohorts. First, we tested whether females and males diagnosed with anxiety or depression differ in terms of their genetic risk for ADHD, assessed as polygenic risk scores (PRS). Second, we tested whether females and males with ADHD differed in ADHD genetic risk burden. We used three different diagnostic definitions: registry‐based clinical diagnoses, screening‐based research diagnoses and algorithm‐based research diagnoses, to investigate possible referral biases.

Results

In individuals with a registry‐based clinical diagnosis of anxiety or depression, females had higher ADHD PRS than males [OR(CI) = 1.39 (1.12–1.73)] but there was no sex difference for screening‐based [OR(CI) = 1.15 (0.94–1.42)] or algorithm‐based [OR(CI) = 1.04 (0.89–1.21)] diagnoses. There was also no sex difference in ADHD PRS in individuals with ADHD diagnoses that were registry‐based [OR(CI) = 1.04 (0.84–1.30)], screening‐based [OR(CI) = 0.96 (0.85–1.08)] or algorithm‐based [OR(CI) = 1.15 (0.78–1.68)].

Conclusions

This study provides genetic evidence that ADHD risk may be more likely to manifest or be diagnosed as anxiety or depression in females than in males. Contrary to some earlier studies, the results do not support increased ADHD genetic risk in females with ADHD as compared to affected males.     

A CACNA1D mutation in a patient with persistent hyperinsulinaemic hypoglycaemia,heart defects,and severe hypotonia

Congenital hyperinsulinaemic hypoglycaemia (HH) can occur in isolation or it may present as part of a wider syndrome. For approximately 40%‐50% of individuals with this condition, sequence analysis of the known HH genes identifies a causative mutation. Identifying the underlying genetic aetiology in the remaining cases is important as a genetic diagnosis will inform on recurrence risk, may guide medical management and will provide valuable insights into β‐cell physiology. We sequenced the exome of a child with persistent diazoxide‐responsive HH, mild aortic insufficiency, severe hypotonia, and developmental delay as well as the unaffected parents. This analysis identified a de novo mutation, p.G403D, in the proband's CACNA1D gene. CACNA1D encodes the main L‐type voltage‐gated calcium channel in the pancreatic β‐cell, a key component of the insulin secretion pathway. The p.G403D mutation had been reported previously as an activating mutation in an individual with primary hyper‐aldosteronism, neuromuscular abnormalities, and transient hypoglycaemia. Sequence analysis of the CACNA1D gene in 60 further cases with HH did not identify a pathogenic mutation. Identification of an activating CACNA1D mutation in a second patient with congenital HH confirms the aetiological role of CACNA1D mutations in this disorder. A genetic diagnosis is important as treatment with a calcium channel blocker may be an option for the medical management of this patient.     

Epidemiology,clinical characteristics,and genetic etiology of neonatal diabetes in Japan

Neonatal diabetes mellitus (NDM) is a rare but potentially devastating metabolic disorder, with a reported incidence of one per 300 000–500 000 births generally, and hyperglycemia develops within the first 6 months of life. NDM is classified into two categories clinically. One is transient NDM (TNDM), in which insulin secretion is spontaneously recovered by several months of age, but sometimes recurs later, and the other is permanent NDM (PNDM), requiring lifelong medication. Recent molecular analysis of NDM identified at least 12 genetic abnormalities: chromosome 6q24, KCNJ11, ABCC8, INS, FOXP3, GCK, IPF1, PTF1A, EIF2AK3, GLUT2, HNF1β, and GLIS3. Of these, imprinting defects on chromosome 6q24 and the KCNJ11 mutation have been recognized as the major causes of TNDM and PNDM, respectively, in Caucasian subjects. Although the pathogenesis and epidemiology of NDM in Japan seem to be clinically distinct, they are still unclear. In this review, we summarize the epidemiology, clinical characteristics, and genetic etiology in Japanese patients with NDM compared with the data on Caucasian patients.