Chromosome 18p Deletion Syndrome

Alternative Names

  • 18p-Syndrome
  • De Grouchy Syndrome
  • 18p Monosomy
  • Partial Monosomy 18p
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WHO-ICD-10 version:2010

Congenital malformations, deformations and chromosomal abnormalities

Chromosomal abnormalities, not elsewhere classified

OMIM Number


Mode of Inheritance

Autosomal dominant; Isolated cases

Gene Map Locus



Chromosome 18p deletion syndrome, as the name suggests, is a result of a deletion of all or part of the short arm of chromosome 18. It is one of the most frequently occurring chromosomal aberrations. The condition is characterized by dysmorphic features, growth deficiencies, speech delays, and mental retardation. Interestingly, affected individuals show minimal abnormalities at birth; the clinical features becoming more apparent by three-years of age. Craniofacial defects presented in this condition include holoprosencephaly, microcephaly, brachycephaly, ocular hypertelorism, broad, flat nose, cleft palate, and tooth abnormalities. Other characteristic features include funnel chest, enlarged labia majora, micropenis, cryptorchidism, small hands and feet, and a short, webbed neck. The severity of the phenotype varies according to the length and type of deletion.

Molecular Genetics

Most of the cases of this condition are due to de novo deletions or translocations between 18p and the long arm of any other acrocentric chromosome. The most common karyotypes are del(18)(pter-p11), del(18)(pter-q11), del(18)(p11.23-pter), del(18p) mosaicism, del(18p) in mosaicism dup(18q), del(18p) with dup(1)(q42-qter), del(18p) with dup(3)(pter-p21), del(18p) with dup(9q), del(18p) with XO/XY mosaicism, and del(18p) with XXY.

Epidemiology in the Arab World

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Other Reports

United Arab Emirates

El Kalla et al. (1992) reported the case of an infant with multiple congenital anomalies, and tetralogy of Fallot.  Karyotypic analysis revealed a karyotype of 45, X, t(Y;18)(q12;11.2).  El Kalla et al. (1992) opined that except for the severity of the heart defect, the patient’s anomalies were consistent with chromosome 18p deletion syndrome.

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