Noonan-like syndrome with loose anagen hair

Definition

Noonan-like syndrome with loose anagen hair is characterized by facial features suggestive of Noonan syndrome (macrocephaly, high forehead, wide-set eyes or hypertelorism, palpebral ptosis, and low-set and posteriorly rotated ears) along with hair that resembles loose anagen hair syndrome (pluckable, sparse, thin and slow-growing).

Cause

The condition is caused by mutations in the SHOC2 gene.

Inheritance

Autosomal dominant pattern, a 50/50 chance.

It follows an autosomal dominant pattern of inheritance.

Signs and symptoms

This condition is characterized by facial features suggestive of Noonan syndrome (macrocephaly, high forehead, wide-set eyes or hypertelorism, palpebral ptosis, and low-set and posteriorly rotated ears) along with hair that resembles loose anagen hair syndrome (pluckable, sparse, thin and slow-growing). Other features include frequent congenital heart defects, distinctive skin features (darkly pigmented skin with eczema or ichthyosis), short stature which may be associated with a growth hormone deficiency, and developmental delays.

Clinical presentation

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

80%-99% of people have these symptoms

• Delayed skeletal maturation(Delayed bone maturation)
• Low posterior hairline(Low hairline at back of neck)
• Low-set, posteriorly rotated ears
• Short nose(Decreased length of nose)
• Short stature(Decreased body height)
• Sparse scalp hair(Reduced/lack of hair on scalp)
• Webbed neck(Neck webbing)

30%-79% of people have these symptoms

• Anteverted nares(Nasal tip, upturned)
• Aplasia/Hypoplasia of the eyebrow(Absence of eyebrow)
• Deep philtrum
• Epicanthus(Eye folds)
• Hydrocephalus(Too much cerebrospinal fluid in the brain)
• Hypertrophic cardiomyopathy(Enlarged and thickened heart muscle)
• Macrotia(Large ears)
• Pectus excavatum(Funnel chest)
• Pulmonic stenosis(Narrowing of pulmonic valve)

5%-29% of people have these symptoms

• Abnormal fingernail morphology(Abnormal fingernails)
• Abnormal palate morphology(Abnormality of the palate)
• Abnormality of the elbow(Abnormality of the elbows)
• Abnormality of the intervertebral disk
• [[Brachydactyly](Short fingers or toes)
• Carious teeth(Dental cavities)
• Cryptorchidism(Undescended testes)
• Deep palmar crease(Deep palm line)
• Eczema
• Feeding difficulties(Feeding problems)
• Generalized hypotonia(Decreased muscle tone)
• Hearing impairment(Deafness)
• Hypertelorism(Wide-set eyes)
• Hypoplasia of the corpus callosum(Underdevelopment of part of brain called corpus callosum)
• Hypoplastic toenails(Underdeveloped toenails)
• Ichthyosis
• Intellectual disability(Mental deficiency)
• Joint laxity(Joint instability)
• Long eyelashes(Increased length of eyelashes)
• Nasal speech(Nasal voice)
• Thick lower lip vermilion(Increased volume of lower lip)
• Thin vermilion border(Decreased volume of lip)

1%-4% of people have these symptoms

• Keratosis pilaris(Chicken skin)