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Monosomy 18p

General Information (adopted from Orphanet):

Synonyms, Signs:	18p- syndrome De Grouchy syndrome
Number of Symptoms	57
OrphanetNr:	1598
OMIM Id:	146390
ICD-10:	Q93.5
UMLs:
MeSH:
MedDRA:
Snomed:

Prevalence, inheritance and age of onset:

Prevalence:	< 200 cases [Orphanet]
Inheritance:	Unknown Not applicable [Orphanet]
Age of onset:	Neonatal [Orphanet]

Disease classification (adopted from Orphanet):

Parent Diseases:

Chromosomal anomaly with cataract
-Rare eye disease
-Rare genetic disease
Partial deletion of the short arm of chromosome 18
-Rare developmental defect during embryogenesis
-Rare genetic disease

Symptom Information: Sort by abundance

	Symptom Information	Symptom	Abundance	DB Freq
1	(HPO:0000028)	Cryptorchidism		347 / 7739
2	(HPO:0000050)	Hypoplastic male external genitalia		10 / 7739
3	(HPO:0000133)	Gonadal dysgenesis		21 / 7739
4	(HPO:0000054)	Micropenis		257 / 7739
5	(HPO:0008734)	Decreased testicular size		105 / 7739
6	(HPO:0000288)	Abnormality of the philtrum	Very frequent [Orphanet]	54 / 7739
7	(HPO:0000445)	Wide nose	Frequent [Orphanet]	190 / 7739
8	(HPO:0000670)	Carious teeth	Frequent [Orphanet]	145 / 7739
9	(HPO:0000252)	Microcephaly	Frequent [Orphanet]	832 / 7739
10	(HPO:0002162)	Low posterior hairline	Frequent [Orphanet]	88 / 7739
11	(HPO:0000347)	Micrognathia		426 / 7739
12	(HPO:0000277)	Abnormality of the mandible	Frequent [Orphanet]	394 / 7739
13	(HPO:0000286)	Epicanthus	Frequent [Orphanet]	371 / 7739
14	(HPO:0000311)	Round face		104 / 7739
15	(HPO:0000692)	Misalignment of teeth		18 / 7739
16	(HPO:0000431)	Wide nasal bridge		290 / 7739
17	(HPO:0000164)	Abnormality of the teeth	Frequent [Orphanet]	291 / 7739
18	(HPO:0000248)	Brachycephaly	Frequent [Orphanet]	222 / 7739
19	(HPO:0002714)	Downturned corners of mouth	Frequent [Orphanet]	98 / 7739
20	(HPO:0000174)	Abnormality of the palate	Frequent [Orphanet]	298 / 7739
21	(HPO:0000316)	Hypertelorism		644 / 7739
22	(HPO:0005989)	Redundant neck skin		40 / 7739
23	(HPO:0000218)	High palate		356 / 7739
24	(HPO:0000470)	Short neck	Frequent [Orphanet]	345 / 7739
25	(HPO:0008056)	Aplasia/Hypoplasia affecting the eye	Occasional [Orphanet]	142 / 7739
26	(HPO:0000508)	Ptosis	Frequent [Orphanet]	459 / 7739
27	(HPO:0000357)	Abnormal location of ears	Very frequent [Orphanet]	328 / 7739
28	(HPO:0009738)	Abnormality of the antihelix	Very frequent [Orphanet]	37 / 7739
29	(HPO:0000400)	Macrotia		108 / 7739
30	(HPO:0000411)	Protruding ear	Very frequent [Orphanet]	140 / 7739
31	(HPO:0000377)	Abnormality of the pinna		111 / 7739
32	(HPO:0001332)	Dystonia		197 / 7739
33	(HPO:0001263)	Global developmental delay		853 / 7739
34	(HPO:0001249)	Intellectual disability		1089 / 7739
35	(HPO:0004404)	Abnormality of the nipple	Frequent [Orphanet]	54 / 7739
36	(HPO:0000821)	Hypothyroidism	Occasional [Orphanet]	141 / 7739
37	(HPO:0100625)	Enlarged thorax	Frequent [Orphanet]	15 / 7739
38	(HPO:0000767)	Pectus excavatum	Frequent [Orphanet]	244 / 7739
39	(HPO:0009466)	Radial deviation of finger		101 / 7739
40	(HPO:0004279)	Short palm	Very frequent [Orphanet]	323 / 7739
41	(HPO:0001518)	Small for gestational age		107 / 7739
42	(HPO:0004322)	Short stature	Very frequent [Orphanet]	1232 / 7739
43	(HPO:0000822)	Hypertension	Frequent [Orphanet]	224 / 7739
44	(HPO:0030680)	Abnormality of cardiovascular system morphology	Occasional [Orphanet]	355 / 7739
45	(HPO:0001004)	Lymphedema	Occasional [Orphanet]	62 / 7739
46	(HPO:0001252)	Muscular hypotonia	Frequent [Orphanet]	990 / 7739
47	(HPO:0012443)	Abnormality of brain morphology	Occasional [Orphanet]	45 / 7739
48	(HPO:0003745)	Sporadic		131 / 7739
49	(HPO:0400004)	Long ear	Very frequent [Orphanet]	94 / 7739
50	(HPO:0030084)	Clinodactyly		90 / 7739
51	(OMIM)	Contiguous gene deletion syndrome		23 / 7739
52	(OMIM)	Deletion of chromosome 18p11.2		1 / 7739
53	(HPO:0000006)	Autosomal dominant inheritance		2518 / 7739
54	(HPO:0012758)	Neurodevelopmental delay	Very frequent [Orphanet]	949 / 7739
55	(HPO:0001428)	Somatic mutation	Very frequent [Orphanet]	100 / 7739
56	(MedDRA:10058668)	Clinodactyly		91 / 7739
57	(OMIM)	Upturned nostrils		1 / 7739

Associated genes:

ClinVar (via SNiPA)

Gene symbol	Variation	Clinical significance	Reference

Additional Information:

Clinical Description OMIM

The 18p- syndrome was first described in 1963 by de Grouchy et al. (see de Grouchy and Turleau, 1984). The main clinical manifestations are mental retardation, growth retardation, craniofacial dysmorphism including round face, dysplastic ears, wide mouth and ... The 18p- syndrome was first described in 1963 by de Grouchy et al. (see de Grouchy and Turleau, 1984). The main clinical manifestations are mental retardation, growth retardation, craniofacial dysmorphism including round face, dysplastic ears, wide mouth and dental anomalies, and abnormalities of the limbs, genitalia, brain, eyes, and heart. Tsukahara et al. (2001) noted that the round face characteristic in the neonatal period and childhood may change to a long face with linear growth of the height of the face. Buhler et al. (1964) reported an early case of 18p- syndrome. In addition to the typical manifestations of that syndrome, the girl had an abnormality of thyroxine synthesis, most likely a coupling defect (Buhler, 1983). Since the proband was the youngest of 7 sibs and none of the other sibs had a thyroxine defect, Buhler (1983) suggested that the deletion may have 'uncovered' a heterozygous mutation inherited from 1 parent and that the gene locus is on the short arm of chromosome 18. Three patients with 18p- syndrome and hypopituitarism have been reported (Leisti et al., 1973; Buffoni et al., 1976; Artman et al., 1992), suggesting that a factor on chromosome 18 may in some way be involved. In the patient reported by Artman et al. (1992), MRI scan of the brain showed hypoplasia of the hypothalamus and pituitary gland. Although most reported cases have been sporadic, Tsukahara et al. (2001) reported a family in which a mother and her son and daughter were affected. They cited 2 other familial cases reported by Uchida et al. (1965) and Velagaleti et al. (1996). Wester et al. (2006) examined 7 patients with de novo 18p terminal deletions. Genotype-phenotype analysis revealed that the 4 patients with deletions located in the centromeric region at 18p11.1 had mental retardation, whereas of 3 patients with breakpoints distal to 18p11.1 (18p11.22-p11.21), 2 had normal intelligence and 1 had borderline mental retardation, suggesting that a critical region for mental retardation may exist between 18p11.21 and 18p11.1. All of the patients with a breakpoint at 18p11.1 had a broad face, which was seen in only 1 of the patients with a more distal breakpoint. Muscular hypotonia was very common (6 of 7 patients). Wester et al. (2006) noted that slowness of motion and action was more of a problem to some study participants than mental retardation. Language performance was more delayed than mental performance, and the majority had major speech problems.

Symptoms & Signs

	Field	Query
	Disease
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