| Literature DB >> 36012355 |
Merlin G Butler1, Waheeda A Hossain1, Jacob Steinle1, Harry Gao2, Eleina Cox2, Yuxin Niu2, May Quach2, Olivia J Veatch1.
Abstract
Fragile X syndrome (FXS) is the most common inherited cause of intellectual disabilities and the second most common cause after Down syndrome. FXS is an X-linked disorder due to a full mutation of the CGG triplet repeat of the FMR1 gene which codes for a protein that is crucial in synaptogenesis and maintaining functions of extracellular matrix-related proteins, key for the development of normal neuronal and connective tissue including collagen. In addition to neuropsychiatric and behavioral problems, individuals with FXS show physical features suggestive of a connective tissue disorder including loose skin and joint laxity, flat feet, hernias and mitral valve prolapse. Disturbed collagen leads to hypermobility, hyperextensible skin and tissue fragility with musculoskeletal, cardiovascular, immune and other organ involvement as seen in hereditary disorders of connective tissue including Ehlers-Danlos syndrome. Recently, FMR1 premutation repeat expansion or carrier status has been reported in individuals with connective tissue disorder-related symptoms. We examined a cohort of females with features of a connective tissue disorder presenting for genetic services using next-generation sequencing (NGS) of a connective tissue disorder gene panel consisting of approximately 75 genes. In those females with normal NGS testing for connective tissue disorders, the FMR1 gene was then analyzed using CGG repeat expansion studies. Three of thirty-nine females were found to have gray zone or intermediate alleles at a 1:13 ratio which was significantly higher (p < 0.05) when compared with newborn females representing the general population at a 1:66 ratio. This association of connective tissue involvement in females with intermediate or gray zone alleles reported for the first time will require more studies on how the size variation may impact FMR1 gene function and protein directly or in relationship with other susceptibility genes involved in connective tissue disorders.Entities:
Keywords: FMR1 gene; FMR1 gray zone or intermediate alleles; connective tissue-related disorders; fragile X syndrome
Mesh:
Substances:
Year: 2022 PMID: 36012355 PMCID: PMC9408984 DOI: 10.3390/ijms23169090
Source DB: PubMed Journal: Int J Mol Sci ISSN: 1422-0067 Impact factor: 6.208
Molecular and clinical findings in three adult females with FMR1 gray zone repeats in a cohort of females presenting for genetic services.
| Participants | Age (Years) | CGG Repeats | AGG Interruptions | Immune-Mediated | Beighton |
|---|---|---|---|---|---|
| Case #1 | 26 | 20, 51 * | (1; 20 or 51 *) | Polyarthralgia, hypothyroidism, migraines | 7 out of 9 |
| Case #2 | 45 | 33, 48 * | (1; 33 or 48 *) | Positive anti-nuclear antibody (ANA), migraines | 3 out of 8 |
| Case #3 | 44 | 24, 50 * | (0; 24) | Fibromyalgia, polymyositis, lupus, migraines, family history of Churg–Strauss vasculitis | 4 out of 6 |
* Designates the intermediate or gray zone repeats.
Figure 1FMR1 gene repeat testing in female patients presenting for heritable connective tissue disorders (HCTDs). Flow chart with details for patients who presented to the genetics clinic over a 3.5-year period. Next-generation sequencing results for genes included on commercially available connective tissue disorder testing panels were evaluated for 80 unrelated female patients. Unrelated female patients with no variants or variants of unknown significance (VUS) reported as ACMG-classified pathogenic, likely pathogenic or determined potentially pathogenic based on allele frequency, biological conservation, Grantham distance and damaging in silico predictions were followed up with FMR1 triplet repeat testing using an approved polymerase chain reaction (PCR), given a sufficient DNA sample was available.