Table 3b.

Disorders with Non-Brachytelephalangic Chondrodysplasia Punctata and Cervical Spine Anomalies in the Differential Diagnosis of CDPX1

Gene(s)DisorderMOIFindings Distinguishing the Disorder from CDPX1
Clinical FeaturesBiochemical Findings
AGPS
GNPAT
PEX5
PEX7 		RDCP1, 2, 3, & 5 (OMIM PS215100)AR
  • Rhizomelia, profound growth restriction, congenital cataract
  • Absence of nasal hypoplasia
Deficiency of peroxisomal plasmalogen (measured in erythrocytes) is diagnostic.
EBP CDPX2 1XL
  • Asymmetric rhizomesomelia, sectorial cataracts, patchy alopecia, ichthyosis, & atrophoderma
  • Affected individuals are typically female
  • Absence of nasal hypoplasia
↑ 8(9)-cholestenol & 8-dehydrocholesterol levels in plasma
NSDHL 2CHILD syndrome (See NSDHL-Related Disorders.)XL
  • Male lethal, unilateral CDP, rhizomelia, polydactyly, skin findings; one side of the body affected
  • Absence of nasal hypoplasia
↑ 4-methyl- & carboxysterols levels in cultured lymphoblasts (but only occasionally in plasma) 2

AR = autosomal recessive; CDP = chondrodysplasia punctata; CDPX = X-linked chondrodysplasia punctata; CHILD = congenital hemidysplasia, ichthyosis, limb defects; MOI = mode of inheritance; RCDP = rhizomelic chondrodysplasia punctata; XL = X-linked

1.

Also referred to as Conradi-Hünermann syndrome and Happle syndrome.

2.

NSDHL encodes a cholesterol biosynthetic 4-methylsterol dehydrogenase. The enzyme, part of a 4-methylsterol demethylase complex, occurs one step proximal to the EBP sterol isomerase.

From: Chondrodysplasia Punctata 1, X-Linked

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