Coarse facial features

Thickening and rounding of facial soft tissues that progresses over time: heavy supraorbital ridges, depressed nasal bridge with anteverted nares, full lips, large tongue, gum hyperplasia. Often accompanied by hepatosplenomegaly, corneal clouding, joint stiffness, short stature, and developmental change. The key word is progressive. These children typically look unremarkable at birth and coarsen over months to years as substrate accumulates.

Coarse facies in a child almost always means a lysosomal storage disorder. The lysosome is failing to degrade a glycosaminoglycan, oligosaccharide, sphingolipid, or glycolipid, and the macromolecule is depositing in connective tissue. The work-up is built around three questions:

1. What substrate is accumulating? Urine GAGs, urine oligosaccharides, plasma chitotriosidase.
2. Which lysosomal enzyme is deficient? Enzyme assays in leukocytes or fibroblasts narrow to the gene.
3. Is there a treatment? ERT, substrate reduction, and HSCT exist for several. Diagnosis is not academic.

Mucopolysaccharidoses (MPS)

The most common cause overall. Substrate: glycosaminoglycans (heparan, dermatan, keratan, chondroitin sulfate).

• MPS I (Hurler / Scheie): corneal clouding + coarse facies + dysostosis multiplex. ERT and HSCT available.
• MPS II (Hunter): the X-linked MPS, the only one without corneal clouding, distinctive ivory-colored "pebbling" skin lesions on the back.
• MPS III (Sanfilippo): CNS-predominant; coarseness is mild, behavioral regression and sleep disturbance dominate.
• MPS IV (Morquio): spares cognition, severe skeletal dysplasia and odontoid hypoplasia (anesthesia hazard). Less coarse facially than MPS I/II.

Mucolipidoses (ML II / III)

• I-cell disease (ML II) and pseudo-Hurler polydystrophy (ML III): GNPTAB/GNPTG mutations disrupt the mannose-6-phosphate tag that targets enzymes to lysosomes. The lysosome looks empty on EM and the plasma is full of lysosomal enzymes. Look for severe early-onset coarse facies, gingival hyperplasia, restricted joints, with normal urine GAGs (the giveaway: a Hurler-like phenotype without MPS labs).

Oligosaccharidoses

Substrate: oligosaccharide fragments from glycoprotein breakdown.

• α-Mannosidosis: coarse facies, hearing loss, immunodeficiency. Urine oligosaccharides positive.
• Fucosidosis, sialidosis, aspartylglucosaminuria: same screening test.

Sphingolipidoses with coarseness

• GM1 gangliosidosis: infantile form has coarse facies + cherry-red spot + dysostosis multiplex, can look very Hurler-like in the first months.
• Niemann-Pick A: hepatosplenomegaly + cherry-red + neurodegeneration, less classically coarse.
• Gaucher type 3: coarsening with horizontal supranuclear gaze palsy.

Other / non-LSD mimics

• Williams-Beuren syndrome: "elfin" features are sometimes described as coarse, but the overall picture (cocktail-party personality, supravalvular AS, hypercalcemia) is unmistakable and the cause is a 7q11.23 microdeletion, not storage.
• Costello syndrome: RASopathy with coarse facies, loose redundant skin, papillomata, HRAS gain-of-function.
• Hypothyroidism (acquired or congenital): coarseness here is reversible with treatment; always on the screen.

A pragmatic opening sequence for a child with progressive coarse facies:

1. Urine GAGs (quantitative + electrophoresis): covers the MPS family.
2. Urine oligosaccharides: covers the oligosaccharidoses.
3. Leukocyte lysosomal enzyme panel: confirms the specific enzyme.
4. Skeletal survey: dysostosis multiplex is shared across MPS and ML.
5. Slit-lamp: corneal clouding.
6. Cardiac echo: many LSDs have valve disease.
7. Plasma lysosomal enzymes if urine GAGs are negative and ML II/III is on the differential.

If the targeted work-up is unrevealing, broad genetic testing (exome or a lysosomal storage gene panel) is appropriate.