Two novel cases expanding the phenotype of SETD2-related overgrowth syndrome

The SETD2-related overgrowth syndrome is also called "Luscan-Lumish syndrome" (OMIM 616831) with the clinical characteristics of intellectual disability, speech delay, macrocephaly, facial dysmorphism, and autism spectrum disorders. We report on two novel patients a 4.5-year-old boy and a 23-year-old female adolescent with a speech and language developmental delay, autism spectrum disorder and macrocephaly, who were both diagnosed with SETD2-related overgrowth syndrome due to de novo frameshift mutations in the SETD2 gene. Features not previously described which were present in either one of our patients were nasal polyps, a large tongue with creases, a high pain threshold, constipation, and undescended testicles. These features may be related to the syndrome and may need special attention in future patients. Additionally, prevention of obesity should be an important point of attention for patients diagnosed with a SETD2-related overgrowth syndrome

The interferon gamma gene in celiac disease: Augmented expression correlates with tissue damage but no evidence for genetic susceptibility

Celiac disease (CD) is a complex genetic disorder characterized by gluten intolerance. The Th1 immune response, with a key position for interferon gamma (IFN-γ), is an important determinant of intestinal remodeling in CD. We aimed at further ascertaining the role of IFN-γ, either as a genetic factor in the etiology, or as a facilitator of disease initiation/progression. Duodenal biopsies were sampled across distinct histopathological stages of the disease, including refractory CD (RCD), and used to determine IFN-γ gene (IFNG) expression by real-time RT-PCR. INFG expression correlated with the extent of tissue restructuring, reaching a 240-fold higher expression in total villous atrophy compared to healthy tissue. CD and RCD patients with similar lesions had comparable expression levels. Interestingly, patients in complete remission still had 7.6-fold residual over-expression. An INFG marker was tested in three cohorts of Dutch patients for both genetic linkage and association. Linkage analysis yielded no significant scores for IFNG or its flanking markers. In addition, IFNG allele frequencies were not differently distributed between cases and controls. Likewise, all alleles were randomly transmitted to affected children in parents-case trios. There is no evidence for IFNG as a predisposing gene in CD, despite its enhanced expression in patients in complete remission

A new mutation for Huntington disease following maternal transmission of an intermediate allele

New mutations for Huntington disease (HD) originate from CAG repeat expansion of intermediate alleles (27-35 CAG). Expansions of such alleles into the pathological range (≥ 36 CAG) have been exclusively observed in paternal transmission. We report the occurrence of a new mutation that defies the paternal expansion bias normally observed in HD. A maternal intermediate allele with 33 CAG repeats expanded in transmission to 48 CAG repeats causing a de novo case of HD in the family. Retrospectively, the mother presented with cognitive decline, but HD was never considered in the differential diagnosis. She was diagnosed with dementia and testing for HD was only performed after her daughter had been diagnosed. This observation of an intermediate allele expanding into the full penetrance HD range after maternal transmission has important implications for genetic counselling of females with intermediate repeat

Age of onset in Huntington's disease is influenced by CAG repeat variations in other polyglutamine disease-associated genes

We read with great interest the recent article by Tezenas du Montcel et al. (2014), who showed that the age of onset in several spinocerebellar ataxias (SCAs) is modulated by CAG repeat sizes in the normal range in other polyglutamine disease-associated genes. Interestingly, the age of onset in patients with SCA3 was also influenced by the CAG repeat size in the HTT gene: long normal HTT CAG repeat size was associated with a delayed age of onset in SCA3 patients (Tezenas du Montcel et al., 2014). Similarly, in a subsequent study in patients with SCA3 from mainland China, it was shown that the difference in CAG repeat size between the two HTT alleles interacted with the ATXN3 expansion and affected age of onset in these patients (Chen et al., 2016)

Repeat length variations in ATXN1 and AR modify disease expression in Alzheimer's disease

Genomewide association studies (GWASs) have contributed greatly to unraveling the genetic basis of Alzheimer's disease (AD). However, a large amount of “missing heritability” remains. In this exploratory study, we investigated the effect of cytosine-adenine-guanine (CAG) repeats in polyglutamine disease–associated genes (PDAGs) on the risk of AD and its expression. In a cohort of 959 patients diagnosed with AD (Amsterdam Dementia cohort) and 4106 cognitively healthy participants (Leiden 85-plus Study and the Prospective Study of Pravastatin in the Elderly at Risk), we determined the CAG repeat sequences in ATXN1, ATXN2, ATXN3, CACNA1A, ATXN7, TBP, HTT, ATN1, and AR. We did not find a significant association between the risk of AD and variations in CAG repeat numbers of PDAGs. However, we found that differences in CAG repeat numbers in ATXN1, ATXN2, and AR were significantly associated with several clinical and imaging features in AD patients. Specifically, the association between memory performance in patients with AD and the CAG repeat size in the longer ATXN1 allele, and the association between atrophy in the medial temporal lobes and the CAG repeat number in the longer AR allele remained significant after correction for multiple testing. Our findings suggest that repeat polymorphisms in ATXN1 and AR can act as important genetic modifiers of AD, warranting further scrutiny of their role in its missing heritability and pathogenesis

Huntingtin gene repeat size variations affect risk of lifetime depression

Huntington disease (HD) is a severe neuropsychiatric disorder caused by a cytosine-adenine-guanine (CAG) repeat expansion in the HTT gene. Although HD is frequently complicated by depression, it is still unknown to what extent common HTT CAG repeat size variations in the normal range could affect depression risk in the general population. Using binary logistic regression, we assessed the association between HTT CAG repeat size and depression risk in two well-characterized Dutch cohorts-the Netherlands Study of Depression and Anxiety and the Netherlands Study of Depression in Older Persons-including 2165 depressed and 1058 non-depressed persons. In both cohorts, separately as well as combined, there was a significant non-linear association between the risk of lifetime depression and HTT CAG repeat size in which both relatively short and relatively large alleles were associated with an increased risk of depression (beta = -0.292 and beta = 0.006 for the linear and the quadratic term, respectively; both P <0.01 after adjustment for the effects of sex, age, and education level). The odds of lifetime depression were lowest in persons with a HTT CAG repeat size of 21 (odds ratio: 0.71, 95% confidence interval: 0.52 to 0.98) compared to the average odds in the total cohort. In conclusion, lifetime depression risk was higher with both relatively short and relatively large HTT CAG repeat sizes in the normal range. Our study provides important proof-of-principle that repeat polymorphisms can act as hitherto unappreciated but complex genetic modifiers of depression

Rubinstein–Taybi syndrome (CREBBP, EP300)

Mechanisms of disease, diagnostics and therap