Syndromes: select one of the two options below (either a or b) and describe the clinical phenotype, inheritance and the molecular genetic origin of the mutation and the consequence of transmission of the syndrome. Compare and contrast the most important observations concerning the genetics of the syndromes including gene functions.Choices: (a) Beckwith Wiedermann and Silver-Russell syndromes(b) Prader-Willi and Angelman syndromes

Option (b) Prader-Willi and Angelman syndromes

Prader-Willi Syndrome (PWS) and Angelman Syndrome (AS) are both genetic disorders that result from a loss of function of genes in a specific region of chromosome 15 (15q11-q13).

Prader-Willi Syndrome is characterized by severe hypotonia and feeding difficulties in early infancy, followed in later infancy or early childhood by excessive eating and gradual development of morbid obesity. Other features include cognitive impairment, problem behaviors, a distinctive facial appearance, short stature, and hypogonadism.

Angelman Syndrome is characterized by severe developmental delay or intellectual disability, severe speech impairment, gait ataxia and/or tremulousness of the limbs, and a unique behavior with an inappropriate happy demeanor that includes frequent laughing, smiling, and excitability.

The inheritance pattern of both syndromes is complex. Most cases of PWS and AS are not inherited, but occur as random events during the formation of reproductive cells (eggs and sperm) or in early embryonic development.

In terms of molecular genetic origin, both syndromes are usually caused by a deletion in the paternal chromosome 15 in the case of PWS, and in the maternal chromosome 15 in the case of AS. This region of the chromosome is subject to a phenomenon known as genomic imprinting, where some genes are expressed in a parent-of-origin-specific manner. If the paternal copy is missing or damaged (PWS), the genes are not expressed. Similarly, if the maternal copy is missing or damaged (AS), the genes are not expressed.

In terms of gene functions, the genes in this region are involved in growth, development, and the normal function of the nervous system. The exact functions of most of these genes are unknown, but they play essential roles in normal growth and development.

In conclusion, PWS and AS are examples of how the same genetic region can lead to different syndromes depending on whether the mutation is of maternal or paternal origin. They also highlight the importance of genomic imprinting in human disease.