7
Genetic Syndromes: Key Examples
Key Signs Genetics
Melanocortin 4
receptor (MC4R)
deficiency
• Hyperphagia
• Accelerated linear growth
• Insulin resistance
• Autosomal
dominant or
recessive
• Most common
form of
monogenetic
obesity
Proopiomelanocortin
(POMC) deficiency
• Hyperphagia
• Adrenal crisis (ACTH deficiency)
• Hypopigmentation
• Pale skin and red hair
Autosomal
recessive
Leptin deficiency • Hyperphagia
• Hypogonadism
• Absence of growth spurt
• Impaired T cell function
Autosomal
recessive
Bardet-Biedl
Syndrome
• Hyperphagia
• Vision loss
• Polydactyly
• Hypogonadism
• Renal disease
• Metabolic syndrome
Autosomal
recessive
Cohen Syndrome • Central obesity with thin arms
and legs
• Small head with thick hair,
eyebrows, and eyelashes
• Developmental delay
• Retinal dystrophy
• Joint hypermobility
• Overly f riendly behavior
• Neutropenia
Autosomal
recessive
Prader-Willi
Syndrome
• Hypotonia and poor feeding
at birth
• Hyperphagia develops at 2 years
• Thin face with almond-shaped
eyes
• Short stature with small hands/
feet
• Delayed development and
intellectual impairment
• Hypogonadism
• Paternal
chromosome
15 partial loss of
function (usually
not inherited)
• Most common
form of
syndromic
obesity
Albright's Hereditary
Osteodystrophy
• Short stature
• Round face
• Dental abnormalities
• Shortened f ingers/toes
• Pseudohypoparathyroidism
• Associated
with genetic
imprinting in
an autosomal
dominant
manner
