Table 3.

Clinical, Cognitive, Behavior, and Genetic Findings Seen in PWS, PWP in FXS, ALMS, and AHO.

Syndromes	Facial Features	Physical Features	Cognitive/Behavior Features	Genetics
Prader–Willi Syndrome (PWS)	Narrow forehead, almond-shaped eyes, strabismus, short nose with thin upper lip, downturned corners of mouth, dry sticky saliva, enamel hypoplasia	Severe hypotonia, short stature, obesity, osteoporosis, small hands and feet, scoliosis, hypopigmentation, head tilt forward, hypogenitalism	Mild learning impairment, hyperphagia, skin and rectal picking, difficulty with transitions, stubbornness, temper tantrums, perseverative speech, autism, obsessive compulsions, unusual skill with jigsaw puzzles, high pain tolerance	Paternally derived 15q11-q13 deletion (70% of cases), maternal disomy 15 (about 25% of cases), imprinting defects (1–3% of cases)
Prader–Willi Phenotype (PWP) in Fragile X Syndrome (FXS)	Round face, almond-shaped eyes, prominent ears	Obesity, delayed puberty, small penis, hypotonia	Developmental delay, food seeding behavior and hyperphagia, difficulty with transitions, perseverative speech, hand flapping, poor eye contact, autism, obsessive compulsions	FMR1 gene triplet repeat mutations (at chromosome Xq27.3)
Alström Syndrome (ALMS)	Round face, deep-set eyes, thickened skull, thick ears, frontal hair loss	Wide, flat feet with brachydactyly, scoliosis, dental anomalies, truncal obesity, short suture, hypogonadism, cardiomyopathy, vision (cone-rod dystrophy) and hearing loss, type 2 diabetes, progressive pulmonary, renal and hepatic problems with fibrosis	Developmental delay, balance disturbances and neurosensory deficits, depression, autism, obsessive compulsions	ALMS1 gene mutations (at chromosome 2p13)
Albright Hereditary Osteodystrophy (AHO)	Rounded face with short nose and short neck, delayed dental eruption or enamel hypoplasia	Moderate obesity, short fourth and fifth metacarpals and metatarsals, short distal phalanx of thumb, small stature, osteoporosis, subcutaneous mineral deposits and basal ganglia, thickened calvarium, variable hypocalcaemia and hyperphosphatemia, occasionally hypothyroidism, hypogonadism and infertility, lens opacity or cataracts, optic atrophy, scoliosis and vertebral anomalies	Mental deficiency (average IQ of 60)	Defects of the GNAS gene or imprinting center domain associated with different forms of pseudohypoparathyroidism (PHP) and pseudopseudohypoparathyroidism (PPHP) depending on parent of origin. Maternal inheritance leads to PHP-Ia (AHO plus hormone resistance) while paternal inheritance leads to PHPP or AHO without evidence of resistance to parathyroid hormone (PTH)