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Topic Review
PGT-SR
Preimplantation genetic testing for structural rearrangements (PGT-SR) was one of the first applications of PGT, with initial cases being worked up in the Delhanty lab. It is the least well-known of the various forms of PGT but nonetheless provides effective treatment for many carrier couples. Structural chromosomal rearrangements (SRs) lead to infertility, repeated implantation failure, pregnancy loss, and congenitally affected children, despite the balanced parent carrier having no obvious phenotype. A high risk of generating chromosomally unbalanced gametes and embryos is the rationale for PGT-SR, aiming to select for those that are chromosomally normal, or at least balanced like the carrier parent. PGT-SR largely uses the same technology as PGT-A, i.e., initially FISH, superseded by array CGH, SNP arrays, Karyomapping, and, most recently, next-generation sequencing (NGS). Trophectoderm biopsy is now the most widely used sampling approach of all PGT variants, though there are prospects for non-invasive methods. In PGT-SR, the most significant limiting factor is the availability of normal or balanced embryo(s) for transfer. Factors directly affecting this are rearrangement type, chromosomes involved, and sex of the carrier parent. De novo aneuploidy, especially for older mothers, is a common limiting factor.
  • 1.0K
  • 27 Mar 2023
Topic Review
GFM1 Gene
G elongation factor mitochondrial 1
  • 1.0K
  • 25 Dec 2020
Topic Review
22q13.3 Deletion Syndrome
22q13.3 deletion syndrome, which is also known as Phelan-McDermid syndrome, is a disorder caused by the loss of a small piece of chromosome 22. The deletion occurs near the end of the chromosome at a location designated q13.3.  
  • 1.0K
  • 25 Dec 2020
Topic Review
Cap Myopathy
Cap myopathy is a disorder that primarily affects skeletal muscles, which are muscles that the body uses for movement. People with cap myopathy have muscle weakness (myopathy) and poor muscle tone (hypotonia) throughout the body, but they are most severely affected in the muscles of the face, neck, and limbs. The muscle weakness, which begins at birth or during childhood, can worsen over time.
  • 1.0K
  • 24 Dec 2020
Topic Review
Zellweger Spectrum Disorder
Zellweger spectrum disorder is a group of conditions that have overlapping signs and symptoms and affect many parts of the body.
  • 1.0K
  • 24 Dec 2020
Topic Review
Pfeiffer Syndrome
Pfeiffer syndrome is a genetic disorder characterized by the premature fusion of certain skull bones (craniosynostosis). This early fusion prevents the skull from growing normally and affects the shape of the head and face. Pfeiffer syndrome also affects bones in the hands and feet.
  • 1.0K
  • 24 Dec 2020
Topic Review
Branchio-Oculo-Facial Syndrome
Branchio-oculo-facial syndrome is a condition that affects development before birth, particularly of structures in the face and neck. Its characteristic features include skin anomalies on the neck, malformations of the eyes and ears, and distinctive facial features.
  • 1.0K
  • 24 Dec 2020
Topic Review
Congenital Metabolic Bone Disorders's Fragility
Bone fragility is a pathological condition caused by altered homeostasis of the mineralized bone mass with deterioration of the microarchitecture of the bone tissue, which results in a reduction of bone strength and an increased risk of fracture, even in the absence of high-impact trauma. The most common cause of bone fragility is primary osteoporosis in the elderly. However, bone fragility can manifest at any age, within the context of a wide spectrum of congenital rare bone metabolic diseases in which the inherited genetic defect alters correct bone modeling and remodeling at different points and aspects of bone synthesis and/or bone resorption, leading to defective bone tissue highly prone to long bone bowing, stress fractures and pseudofractures, and/or fragility fractures. 
  • 1.0K
  • 09 Oct 2021
Topic Review
Fraser Syndrome
Fraser syndrome is a rare disorder that affects development starting before birth. Characteristic features of this condition include eyes that are completely covered by skin and usually malformed (cryptophthalmos), fusion of the skin between the fingers and toes (cutaneous syndactyly), and abnormalities of the genitalia and the urinary tract (genitourinary anomalies). Other tissues and organs can also be affected. Depending on the severity of the signs and symptoms, Fraser syndrome can be fatal before or shortly after birth; less severely affected individuals can live into childhood or adulthood.
  • 999
  • 25 Dec 2020
Topic Review
Ankyrin-B syndrome
Ankyrin-B syndrome is associated with a variety of heart problems related to disruption of the heart's normal rhythm (arrhythmia). Heart rhythm is controlled by electrical signals that move through the heart in a highly coordinated way. In ankyrin-B syndrome, disruption of different steps of electrical signaling can lead to arrhythmia, and the resulting heart problems vary among affected individuals.
  • 998
  • 24 Dec 2020
Topic Review
SATB2-Associated Syndrome
SATB2-associated syndrome is a condition that affects several body systems. It is characterized by intellectual disability, severe speech problems, dental abnormalities, other abnormalities of the head and face (craniofacial anomalies), and behavioral problems.
  • 998
  • 24 Dec 2020
Topic Review
DCas9 Activation System
CRISPR activation (CRISPRa) is one type of CRISPR tool that use modified versions of dCas9, a mutation of Cas9 without endonuclease activity, with added transcriptional activators on dCas9 or the guide RNAs (gRNAs). Like a standard CRISPR-Cas9 system, dCas9 activation systems rely on similar components such as Cas9 variants for modulation or modification of genes, gRNAs to guide Cas9 to intended targets, and vectors for introduction into cells. However, while a standard CRISPR-Cas9 system relies on creating breaks in DNA through the endonuclease activity of Cas9 and then manipulating DNA Repair mechanisms for gene editing, dCas9 activation systems are modified and employ transcriptional activators to increase expression of genes of interest. Such systems are usable for many purposes including but not limited to, genetic screens and overexpression of proteins of interest.
  • 998
  • 12 Oct 2022
Topic Review
Meckel Syndrome
Meckel syndrome is a disorder with severe signs and symptoms that affect many parts of the body.
  • 997
  • 23 Dec 2020
Topic Review
X-linked Chondrodysplasia Punctata 2
X-linked chondrodysplasia punctata 2 is a disorder characterized by bone, skin, and eye abnormalities. It occurs almost exclusively in females.  
  • 997
  • 24 Dec 2020
Topic Review
CCFDN
Congenital cataracts, facial dysmorphism, and neuropathy (CCFDN) is a rare disorder that affects several parts of the body. It is characterized by a clouding of the lens of the eyes at birth (congenital cataracts) and other eye abnormalities, such as small or poorly developed eyes (microphthalmia) and abnormal eye movements (nystagmus). Affected individuals, particularly males, often have distinctive facial features that become more apparent as they reach adulthood. These features include a prominent midface, a large nose, protruding teeth, and a small lower jaw.
  • 997
  • 04 Jan 2021
Topic Review
Kabuki Syndrome
Kabuki syndrome is a disorder that affects many parts of the body. It is characterized by distinctive facial features including arched eyebrows; long eyelashes; long openings of the eyelids (long palpebral fissures) with the lower lids turned out (everted) at the outside edges; a flat, broadened tip of the nose; and large protruding earlobes. The name of this disorder comes from the resemblance of its characteristic facial appearance to stage makeup used in traditional Japanese Kabuki theater.
  • 996
  • 23 Dec 2020
Topic Review
Liebenberg Syndrome
Liebenberg syndrome is a condition that involves abnormal development of the arms, resulting in characteristic arm malformations that can vary in severity.
  • 996
  • 24 Dec 2020
Topic Review
Estimation of Genetic Ancestry
Admixed populations arise when two or more ancestral populations interbreed. As a result of this admixture, the genome of admixed populations is defined by tracts of variable size inherited from these parental groups and has particular genetic features that provide valuable information about their demographic history. Diverse methods can be used to derive the ancestry apportionment of admixed individuals, and such inferences can be leveraged for the discovery of genetic loci associated with diseases and traits, therefore having important biomedical implications. 
  • 996
  • 09 Jul 2021
Topic Review
Horner Syndrome
Horner syndrome is a disorder that affects the eye and surrounding tissues on one side of the face and results from paralysis of certain nerves.
  • 995
  • 23 Dec 2020
Topic Review
KCNA1 Gene
Potassium voltage-gated channel subfamily A member 1
  • 995
  • 23 Dec 2020
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