Preimplantation Genetic Haplotyping
Encyclopedia
Preimplantation Genetic Haplotyping (PGH) is a clinical method of preimplantation genetic diagnosis
(PGD). PGH was first developed in 2006 at London
's Guy's Hospital
and greatly advances PGD by using DNA fingerprinting rather than identifying the actual genetic signature (such as point mutation
s).
Preimplantation genetic diagnosis
In medicine and genetics pre-implantation genetic diagnosis refers to procedures that are performed on embryos prior to implantation, sometimes even on oocytes prior to fertilization. PGD is considered another way to prenatal diagnosis...
(PGD). PGH was first developed in 2006 at London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...
's Guy's Hospital
Guy's Hospital
Guy's Hospital is a large NHS hospital in the borough of Southwark in south east London, England. It is administratively a part of Guy's and St Thomas' NHS Foundation Trust. It is a large teaching hospital and is home to the King's College London School of Medicine...
and greatly advances PGD by using DNA fingerprinting rather than identifying the actual genetic signature (such as point mutation
Point mutation
A point mutation, or single base substitution, is a type of mutation that causes the replacement of a single base nucleotide with another nucleotide of the genetic material, DNA or RNA. Often the term point mutation also includes insertions or deletions of a single base pair...
s).
Scope
Compared with previous PGD techniques, PGH allows:- The ability to screen male embryoEmbryoAn embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
s- hence male embryos can be screened for X-linked disorders such as Duchenne muscular dystrophyDuchenne muscular dystrophyDuchenne muscular dystrophy is a recessive X-linked form of muscular dystrophy, which results in muscle degeneration, difficulty walking, breathing, and death. The incidence is 1 in 3,000 boys. Females and males are affected, though females are rarely affected and are more often carriers...
and Becker's muscular dystrophyBecker's muscular dystrophyBecker muscular dystrophy is an X-linked recessive inherited disorder characterized by slowly progressive muscle weakness of the legs and pelvis.... - hence having both male and female embryos screened, an increase the number of embryos that can be implanted
- hence male embryos can be screened for X-linked disorders such as Duchenne muscular dystrophy
- A much greater number of individual tests
- Increased reliability
- Higher success rate
Uses
PGH has been used to screen for:- cystic fibrosisCystic fibrosisCystic fibrosis is a recessive genetic disease affecting most critically the lungs, and also the pancreas, liver, and intestine...
- Duchenne muscular dystrophyDuchenne muscular dystrophyDuchenne muscular dystrophy is a recessive X-linked form of muscular dystrophy, which results in muscle degeneration, difficulty walking, breathing, and death. The incidence is 1 in 3,000 boys. Females and males are affected, though females are rarely affected and are more often carriers...
- Huntington's diseaseHuntington's diseaseHuntington's disease, chorea, or disorder , is a neurodegenerative genetic disorder that affects muscle coordination and leads to cognitive decline and dementia. It typically becomes noticeable in middle age. HD is the most common genetic cause of abnormal involuntary writhing movements called chorea...
- Spinal Muscular AtrophySpinal muscular atrophySpinal Muscular Atrophy is a neuromuscular disease characterized by degeneration of motor neurons, resulting in progressive muscular atrophy and weakness. The clinical spectrum of SMA ranges from early infant death to normal adult life with only mild weakness...
- Alport's syndrome
- Von Hippel-Lindau diseaseVon Hippel-Lindau diseaseVon Hippel–Lindau is a rare, autosomal dominant genetic condition in which hemangioblastomas are found in the cerebellum, spinal cord, kidney and retina. These are associated with several pathologies including renal angioma, renal cell carcinoma and pheochromocytoma...
- Sickle-cell diseaseSickle-cell diseaseSickle-cell disease , or sickle-cell anaemia or drepanocytosis, is an autosomal recessive genetic blood disorder with overdominance, characterized by red blood cells that assume an abnormal, rigid, sickle shape. Sickling decreases the cells' flexibility and results in a risk of various...
- and recurrent Hydatidiform moleHydatidiform moleMolar pregnancy is an abnormal form of pregnancy, wherein a non-viable, fertilized egg implants in the uterus, and thereby converts normal pregnancy processes into pathological ones. It is characterized by the presence of a hydatidiform mole...