Clinical Genetics - General = Genodermatoses (TRANSFERRED)

Question 1

Reference: Genetics residents in-training examination – Fall 2020

A. Name two genetic conditions that can present as a ‘collodion baby’

B. What is the enzyme name (the enzyme deficiency) involved in X-linked ichthyosis?

C. What is a possible pregnancy complication when the fetus has X-linked ichthyosis?

D. Sjögren–Larsson syndrome features ichthyosis and what other main feature/system issues?

Answer 1

A. 
Harlequin Ichthyosis
ARCI- lamellar ichthyosis
Autosomal Recessive Congenital Ichthyosis (ARCI) -  Congenital Ichthyosiform Erythroderma type (CIE, Non-bullous CIE) – all same thing. 
Netherton syndrome

B.
STS deficiency (steroid sulfatase deficiency)

C.
Deficiency of the sulfatase enzyme in the placenta may result in failure of labor to initiate or progress. (Decreased maternal serum or urine estriol levels and dehydroepiandrosterone levels can suggest X-linked ichthyosis in the fetus.)

D. 
Spasticity
Intellectual disability 
Macular degeneration
Retinal thinning
Corneal opacities
Severe pruritis

Question 2

Reference: Genetics residents in-training examination – Fall 2020

You are referred a 5 month old baby with 4 CALMs.

1. List 5 potential diagnoses.
2. You see the baby in clinic a month later. What are 5 most important targeted areas to examine to help with your differential diagnosis?
3. List the clinical criteria for NF1.
4. How many do you need to make a diagnosis?
5. What cancer screening is suggested for adults with NF1?

Answer 2

1. NF1, CMMRD, Isolated CALM, Legius, Noonan
2. Length, HC, # and Size of CALM, freckling in axilla or groin, limb and face asymmetry/deformity
3. Six or more café au lait macules,
   Two or more neurofibromas or one plexiform neurofibroma,
   Freckling in the axillary or inguinal regions,
   Optic glioma,
   Two or more Lisch nodules,
   A distinctive osseous lesion such as sphenoid dysplasia or tibial pseudarthrosis,
   First degree relative with NF1
4. Two or more
5. Breast cancer screening for women