2025 – PAGE 255 – GENETICS & INHERITED DISEASES

NAIL PATELLA SYNDROME

Obviously, look for abnormal nails and patellae for nail patella syndrome. Thumbnails are most often affected, then fingernails, and then toenails. Nail deformities may be mild or severe (pitting, ridging, splitting, discoloration or even absence). Patellae deformities also vary (small, irregular, or absent). There are also sometimes elbow or iliac deformities (low yield).

IMAGE: www.pbrlinks.com/NAILPATELLA1
IMAGE: www.pbrlinks.com/NAILPATELLA2 (hypoplasia of patella)

MNEMONIC: maNntra

NOONAN SYNDROME (AKA NOONAN’S SYNDROME)

Noonan syndrome (or Noonan’s syndrome) patients have pulmonic stenosis, pectus excavatum, a webbed neck, low-set ears, and hypertrophic obstructive cardiomyopathy (AKA HCM or HOCM). The webbed neck and low-set ears are features common to Turner’s syndrome, so look for mention of a normal karyotype to help you zone in on a diagnosis of Noonan syndrome. Also remember that this disorder affects both females and males.

• IMAGE: www.pbrlinks.com/NOONAN1
• IMAGE: www.pbrlinks.com/NOONAN2
• MNEMONIC: manNtra from the introductory mnemonic
• MNEMONIC: Pul-NUN-ic Stenosis
• MNEMONIC: Imagine PULLing a NUN (NOONan) BY HER LOW-SET EARS. Her skin stretches and causes WEBBING OF THE NECK. The NUN eventually FALLS ON HER CHEST creating a PECTUS DEFORMITY that pushes inward on her pulmonary arteryand causes PULL-NUN-IC STENOSIS. She finally stands up, HOCs a spit ball into her PALM and slaps you in the face!
  • HOCs: Represents hypertrophic obstructive cardiomyopathy.
  • PALM: In case PULL-NUN-IC stenosis doesn’t work for you, the PALM represents a PALM-NUN-IC stenosis.

ACHONDROPLASIA (AKA DWARFISM)

While 15-20% of achondroplasia (AKA dwarfism) cases are due to autosomal dominant inheritance, the rest are due to sporadic mutations. Patients are short, have macrocephaly, mild hypotonia, short arms/legs, a relatively normal torso, and “trident-like” fingers. They also have a GENU VARUM deformity. They have a normal IQ. The cause of sudden death is COMPRESSION of the CERVICOMEDULLARY JUNCTION. Reproductive fitness is severely affected. Cases due to sporadic mutations are much more common than cases due to inheritance.

IMAGE: www.pbrlinks.com/ACHONDROPLASIA1
IMAGE: www.pbrlinks.com/ACHONDROPLASIA2
IMAGE: www.pbrlinks.com/ACHONDROPLASIA3
IMAGE: www.pbrlinks.com/ACHONDROPLASIA4
IMAGE: www.pbrlinks.com/ACHONDROPLASIA5

MNEMONIC: Imagine a “mini-me” version of Akon walking around with bowed legs, chanting/rapping his mantra of “Down with the MANNTRA!” You could also imagine Mini-Me or Weeman being naughty and running around with a devilish TRIDENT!