65 Nail–Patella Syndrome

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65 Nail–Patella Syndrome

NPS1, Onycho-osteodysplasia, Fong disease

Nail dysplasia, patella hypoplasia/aplasia, iliac horns, limited elbow mobility, nephropathy

Frequency: Rare. Over 400 cases reported.

Genetics

Autosomal dominant (OMIM 161200) with variable expression; caused by mutations in the LIM homeo- domain protein LMX1B, whose locus has been mapped to 9q34.1.

Clinical Features

• Decreased pronation-supination, inability to ex- tend the elbows, antecubital pterygium

• Absent/dysplastic nail with longitudinal splits, triangular lunula (nail changes progressively less pronounced from thumb to 5th ﬁnger)

• Clinodactyly, camptodactyly

• Absent or hypoplastic, dislocated patellas, limited knee mobility

• Shoulder dysplasia, spinal scoliosis

• Nephropathy, proteinuria (50% of cases), recur- rent urinary infections, renal failure in rare cases

Differential Diagnosis

• Anonychia

• Familial patellar dislocation

Radiographic Features Pelvis

• Small iliac wings with horns arising from the central area of the iliac wings, directed posterolateral- ly (horns are absent in a few cases)

Limbs

• Absent or hypoplastic patellas, irregularly ossiﬁed patellas, dislocated patellas

• Disproportionate prominence of medial condyle of femur

• Hypoplasia of proximal radius, with lateral incli- nation of radial head, hypoplasia of lateral humer- al epicondyle, radial subluxation or dislocation

• Clinodactyly, camptodactyly

• Equinovalgus deformity of hindfoot, calcaneoval- gus deformity, forefoot supination and lateral subluxation of tarsal-metatarsal joints

• Ball-and-socket ankle

Chest

• Hypoplastic scapula with glenoid dysplasia, thick- ening and convexity of lateral border of scapula

• Pectus carinatum Joints

• Laxity of ﬁnger joints

• Asymmetrical development of joints (hypoplasia or hyperplasia)

Bibliography

Bennett WM, Musgrave JE, Campbell RA, Elliot D, Cox R, Brooks RE, Lovrien EW, Beals RK, Porter GA. The nephropathy of the nail-patella syndrome: clinocopatho- logic analysis of 11 kindreds. Am J Med Genet 1973; 54:

304–19

Dreyer SD, Zhou G, Baldini A, Winterpacht A, Zabel C, Cole W, Johnson RL, Lee B. Mutations in LMX1B cause abnormal skeletal patterning and renal dysplasia in nail patella syndrome. Nat Genet 1998; 19: 47–50

Karabulut N, Ariyurek M, Erol C, Tacal T, Balkanci F. Imaging of “iliac horns” in nail-patella syndrome. J Comput Assist Tomogr 1996; 20: 530–1

Looij BJ, Te Slaa RL, Hogewind BL, van de Kamp JJP. Genetic counselling in hereditary osteo-onychodysplasia (HOOD, nail-patella syndrome) with nephropathy. J Med Genet 1988; 25: 682–6

Mastroiacovo P, Dallapiccola B,Andria G, Camera G, Lungarot- ti MS. Difetti congeniti e sindromi malformative. McGraw- Hill, Milan, 1990

McIntosh I, Dreyer SD, Clough MV, Dunston JA, Eyaid W, Roig CM, Montgomery T, Ala-Mello S, Kaitila I, Winterpacht A, Zabel B, Frydman M, Cole WG, Francomano CA, Lee B.

Mutation analysis of LMX1B gene in nail-patella syndrome patients. Am J Hum Genet 1998; 63: 1651–8

Morita T, Laughlin O, Kawano K, Kimmelstiel P. Nail-patella syndrome. Arch Intern Med 1973; 131: 271–7

Zimmerman C. Iliac horns: a pathognomonic roentgen sign of familial onycho-osteodysplasia. AJR Am J Roentgenol 1961;

86: 478–83

Yarali HN, Erden GA, Karaarslan F, Bilgic SC, Cumhur T. Clav- icular horn: another bony projection in nail-patella syndrome. Pediatr Radiol 1995; 25: 549–50

Nail–Patella Syndrome 772

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Fig. 65.1 a, b. Nail hypo-/dysplasia, more pronounced on ﬁngers than on toes a Patient 1, age 4 years. b Patient 2, age 7 years (brother of patient 1). (Reprinted, with permission, from Mastroiacovo et al. 1990)

a b

Fig. 65.2. a Patient 3, age 5 years; b patient 4, age 18 years;

cpatient 5, adult (father of patient 3). Note characteristic iliac horns arising from central portion of iliac bones and project- ing laterally as triangular or pyramidal bony excrescences. Ilia

are narrow and characteristic in shape: ﬂattening of superolat- eral borders of iliac wings (b, c), with anterior superior iliac spine located at their most inferior and lateral margin. Note coxa valga (a, b) and marked shortening of femoral necks (c) a

b

c

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Fig. 65.3. a, bPatient 3, age 5 years; c patient 4, age 18 years. Note that patellas are either absent (a, b) or hypoplastic (c)

a b c

Fig. 65.4. Patient 3, age 5 years. Mild deﬁciency of proximal radius, with moderate radial bowing. Scapula is hypoplastic.

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Fig. 65.5. Patient 4, 18 years. Note unusual exostoses arising from the lateral border of both meta- tarsals and directed posteriorly as long, pedunculated bony excrescences