2019 - 2023Available
6papers in this issue.
KBG syndrome (KBGS) is a multisystem disorder characterized by short stature, distinctive facial features including macrodontia of upper central permanent incisors, and developmental/cognitive delay. It is caused by variants or deletion of Ankyrin Repeat Domain 11 (ANKRD11) located in chromosome 16q24.3. Since its initial report in 1975, KBG syndrome has been recognized as an exceedingly rare disorder. However, recent advancements in genetic diagnostic techniques have led to an increase in both the diagnosis rate and the number of reported cases, contributing to a rapid increase in its global prevalence. We review the clinical aspects of KBGS, including previously reported and newly reported cases, as well as the related genetic patterns discovered so far.
Conventional evaluation method for identifying the organic cause of short stature has a low detection rate. If an infant who is small for gestational age manifests postnatal growth deterioration, triangular face, relative macrocephaly, and protruding forehead, a genetic testing of IGF2, H19, GRB10, MEST, CDKN1, CUL7, OBSL1, and CCDC9 should be considered to determine the presence of Silver–Russell syndrome and 3-M syndrome. If a short patient with prenatal growth failure also exhibits postnatal growth failure, microcephaly, low IGF-1 levels, sensorineural deafness, or impaired intellectual development, genetic testing of IGF1 and IGFALS should be conducted. Furthermore, genetic testing of GH1, GHRHR, HESX1, SOX3, PROP1, POU1F1, and LHX3 should be considered if patients with isolated growth hormone deficiency have short stature below −3 standard deviation score, barely detectable serum growth hormone concentration, and other deficiencies of anterior pituitary hormone. In short patients with height SDS <−3 and high growth hormone levels, genetic testing should be considered to identify GHR mutations. Lastly, when severe short patients (height z score < −3) exhibit high levels of prolactin and recurrent pulmonary infection, genetic testing should be conducted to identify STAT5B mutations.
Chromosomal microarray (CMA) is primarily recommended for detecting clinically significant copy number variants (CNVs) in the genetic diagnosis of developmental delay, intellectual disability, autism, and congenital malformations. Prenatal CMA is recommended when a fetus has major congenital malformations. The main principles of CMA can be divided into array comparative genomic hybridization and single-nucleotide polymorphism arrays. In the current CMA platforms, these two principles are combined, and detection of genetic abnormalities including CNVs and absence of heterozygosity is facilitated. In this review, I described practical assessment of CMA testing regarding to laboratory management of CMA, interpretation of CNVs, and special considerations for comprehensive genetic counseling.
Pseudohypoparathyroidism (PHP) is very rare and shows heterogeneity with impaired genetic components. PHP is characterized by parathyroid hormone resistance to target organ, related with a GNAS (guanine nucleotide-binding protein α-subunit) mutation and epimutation. PHP receptor is coupled with the stimulatory G protein which activates cyclic adenosine monophosphate formation. PHP type 1A is caused by inactivating mutations on the maternal allele of the GNAS whereas paternal allele mutations cause pseudopseudohypoparathyroidism. PHP type 1B is caused by abnormal patterns of methylation in differentially methylated region which can be divided into partial or complete. This disease has some difficulties to diagnose according to these different molecular alterations caused by complex genetic and epigenetic defects. According to this different molecular alterations, genetic confirmation must be done to discriminate their etiology.
Resistance to thyroid hormone syndrome (RTH) is a genetic disease caused by the mutation of either the thyroid hormone receptor-β (THRB) gene or the thyroid hormone receptor-α (THRA) gene. RTH caused by THRB mutations (RTH-β) is characterized by the target tissue’s response to thyroid hormone, high levels of triiodothyronine and/or thyroxine, and inappropriate secretion of thyroid-stimulating hormone (TSH). THRA mutation is characterized by hypothyroidism that affects gastrointestinal, neurological, skeletal, and myocardial functions. Most patients do not require treatment, and some patients may benefit from medication therapy. These syndromes are characterized by decreased tissue sensitivity to thyroid hormones, generating various clinical manifestations. Thus, clinical changes of resistance to thyroid hormones must be recognized and differentiated, and an approach to the practice of personalized medicine through an interdisciplinary approach is needed.
Background: Ca2+ signaling plays a vital role in neuronal signaling and altered Ca2+ homeostasis in Parkinson’s disease (PD). Overexpression of αSYN significantly promote the Ca2+-Calmodulin (CaM) activity and subsequent nuclear translocation of nuclear factor of activated T cells (NFAT) transcription factor in dopaminergic neurons of midbrain. However, the exact role of Ca2+-CaM and NFAT in PD pathology is yet to be elucidated. Methods: We designed the CaM-NFAT-oligodeoxynucleotide (ODN), a synthetic short DNA containing complementary sequence for NFAT transcription factor and CaM mRNA. Then, the effect of CaM-NFAT-ODN on 1-methyl-4-phenylpyridinium (MPP+)-mediated neurotoxicity was investigated in mimic PD model in vitro. Results: First, the expression of αSYN and CaM was strongly increased in substantia nigra (SN) of PD and the expression of tyrosine hydroxylase (TH) was strongly increased in control SN. Additionally, the expression of apoptosis marker proteins was strongly increased in SN of PD. Transfection of CaM-NFAT-ODN repressed CaM and pNFAT, the target genes of this ODN in rat embryo primary mesencephalic neurons. It also reduced ERK phosphorylation, a downstream target of these genes. These results demonstrated that CaM-NFAT-ODN operated successfully in rat embryo primary mesencephalic neurons. Transfection of CaM-NFAT-ODN repressed TH reduction, αSYN accumulation, and apoptosis by MPP+-induced neurotoxicity response through Ca2+ signaling and mitogen-activated protein kinases (MAPK) signaling. Conclusion: Synthetic CaM-NFAT-ODN has substantial therapeutic feasibility for the treatment of neurodegenerative diseases.