In applied genetics (selective and agricultural breeding), this controversy has reflected the century-long debate over whether dominance or overdominance provides the best explanation for heterosis (hybrid vigor). The classical/balance controversy. The classical hypothesis of genetic variability, often associated with Hermann Muller, maintains that most genes are of a normal wild type, and that most individuals are homozygous for that wild type, while most selection is purifying selection that operates to eliminate deleterious alleles. The balancing hypothesis, often associated with Theodosius Dobzhansky, states that heterozygosity will be common at loci, and that it frequently reflects either directional selection or balancing selection. Selectionists versus neutralists. In theoretical population genetics, selectionists emphasize the primacy of natural selection as a determinant of evolution and of variation within a population, while neutralists favor a form of Motoo Kimuras neutral theory of molecular evolution, which emphasizes the role of genetic drift. Research directions
Enzyme replacement therapy
Enzyme replacement therapy techniques have been investigated for lysosomal storage disorders, and could potentially be used to treat Tay–Sachs as well. The goal would be to replace the nonfunctional enzyme, a process similar to insulin injections for diabetes. However, in previous studies, the HEXA enzyme itself has been thought to be too large to pass through the specialized cell layer in the blood vessels that forms the blood–brain barrier in humans.Researchers have also tried directly instilling the deficient enzyme hexosaminidase A into the cerebrospinal fluid (CSF) which bathes the brain.
Lipoblastoma is a type of rare, subcutaneous, benign, fatty tumor, found in infants, and children, more common in males with tendency of local recurrence. Local recurrence can happen in up to 80% of incompletely resected tumours. Therefore, complete surgical resection is required to prevent recurrence. It arises from embyronic white fat that is rapidly enlarging. Most common locations are at the trunk and extremities.Types include:
Benign lipoblastomatosis, a tumor, also known as an embryonic lipoma, which usually occurs in children under three years old. This is the tumor of brown fat cells. Myxoid lipoblastoma, a cutaneous condition characterized by excess mucin

Specimen
Macroscopic
Grossly, it has a pale yellow, myxoid cut surface with small cystic foci. Microscopic
It has lobules consists of immature adipose tissue separated by fibrous septa and lipoblasts at different stages of maturation, without atypia or mitosis. Plexiform capillary network and mature adipose tissue are seen at the central part of the lobule. See also
Lipoblast
Lipoma


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