Home > D. Systemic pathology > Genetic and developmental anomalies > Chromosomal diseases > Constitutional monosomies > monosomy X

monosomy X

Tuesday 25 January 2005

Epidemiology

- 1/7000 newborns
- increased frequency in abortuses or women with short statute

Synopsis

- no pubertal development
- 50% of cells have chromatin negative Barr bodies
- karyotype 45 XO in some or all cells
- craniofacial anomalies

  • triangular face
  • antimongoloid slant of palpebral fissures
  • epicanthus
  • ptosis
  • highly arched palate
  • manidbular hypoplasia
  • retrognathia

- thoracic anomalies

  • broad thorax
  • shield shaped thorax
  • widely spaced nipples
  • niple hypoplasia (hypoplastic nipples)
  • axillary air absent

- aortic anomalies (12640386)

  • mucopolysaccaride deposition in cardiac valves
    • floppy mitral valve
    • floppy aortic valve

- genitourinary anomalies

  • infantile external genitalia
  • clitoral hypertrophy
  • pubic hair scanty or absent
  • female ducts
  • female external genitalia
  • ovarian dysgenesis
    • ovarian agenesis
    • streak gonads with fibrous tissue resembling ovarian stroma
    • ovaries can be normal in the fetus
  • uterine hypoplasia (hypoplastic uterus)
  • bifid uterus
  • failure of development of secondary sex characters
  • renal malformations (11045397)
    • horseshoe kidney
    • anomalies of renal rotation
    • renal agenesis
    • renal hypoplasia
    • hydronephrosis
    • bifid ureters

- generalized hypoplasia and partial agenesis of the lymphatic system

  • generalized lymphedema
    • cystic hygroma
    • lymphedema of the dorsum of the feet

- skeletal anomalies

  • short bi-iliac distance (11920833)
  • low inner tibial plate
  • slanted downward and inward inner tibial plate with projection beyond metaphysis (Kosowicz sign)
  • cubitus valgus
  • brachymetacarpia (shortness of fourth and fifth metacarpals)
  • raised semilunar carpal bones

- cerebrospinal anomalies (central nervous system anomalies)

  • slight cortical dysplasia
  • gray matter heterotopia
  • hydrocephalus

- sense organs

  • severe myopia
  • congenital cataracts
  • congenital deafness (17095347)

- endocrine anomalies

  • low plasmatic estrogens and pregnanediol
  • increased FSH
  • low urinary 17-ketosteroids

- dysimmunity/autoimmunity

In infants

- small for gestational age
- lymphedema of hands and feet
- excess skin on nape of neck (before pterygium colli)

At puberty

- small stature
- short neck
- webbed neck (pterygium colli)
- low hair line
- ungueal hypoplasia (nail hypoplasia)
- hyperconvex nails
- keloid scars

Tumor predisposition

- gonadal tumors

- halo nevus
- atypical polypoid adenomyoma of uterus
- endometrial adenocarcinoma
- leukemia
- soft tissue tumors

- neuroblastic tumors (14623457, 11464996)

  • adrenal ganglioneuroblastoma
  • ganglioneuroma

- multiple nevi
- retroperitoneal mesenchymoma
- thyroid carcinoma
- anaplastic pulmonary carcinoma
- pituitary eosinophilic adenoma
- pituitary chromophobe adenoma
- hibernoma
- cecal or appendiceal carcinoid tumors
- multiple granular cell myoblastomas
- medulloblastoma
- cerebellar glioma
- meningioma
- melanoma
- endometrial adenocarcinoma
- uterine adenoacanthoma
- vulvar squamous cell carcinoma
- acute myelogenous leukemia
- digestive adenocarcinomas

  • gastric adenocarcinoma
  • colonic adenocarcinoma

Biology

- markedly elevated FSH
- reduced estrogen levels
- atherogenic lipid profile (16705071)

Not associated with gonadal tumors, although case report with mixed germ cell tumor and gonadoblastoma, Archives 1994;118:1135

Micro: streak gonad with fibrous tissue resembling ovarian stroma

Cytogenetics

- 60% of patients with Turner syndrome in 45,X karyotype
- 30% of them a Y-sequence

Variants

- mosaic monosomy X (mosaic Turner syndrome)

  • 46,XY;45,X mosaic
  • 46,XX;45,X mosaic

See also

- somatic monosomy X (9078298)

  • in myelodysplasias (myelodysplastic diseases) (9078298)

References

- Sybert VP, McCauley E. Turner’s syndrome. N Engl J Med. 2004 Sep 16;351(12):1227-38. PMID: 15371580

Portfolio

  • Sexual ambiguity and perineal hypospadias in mosaic monosomy X (...)
  • Sexual ambiguity and perineal hypospadias in mosaic monosomy X (...)
  • Streak gonad in Turner syndrome
  • Streak gonad in Turner syndrome (arrow)