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Achondrogenesis, type IB(ACG1B)

MedGen UID:
78547
Concept ID:
C0265274
Congenital Abnormality
Synonyms: ACG1B; Achondrogenesis Fraccaro type; Achondrogenesis Type 1B
SNOMED CT: Achondrogenesis, type IB (14870002)
Modes of inheritance:
Autosomal recessive inheritance
MedGen UID:
141025
Concept ID:
C0441748
Intellectual Product
Source: Orphanet
A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in individuals with two pathogenic alleles, either homozygotes (two copies of the same mutant allele) or compound heterozygotes (whereby each copy of a gene has a distinct mutant allele).
 
Gene (location): SLC26A2 (5q32)
 
Monarch Initiative: MONDO:0010966
OMIM®: 600972
Orphanet: ORPHA93298

Disease characteristics

Excerpted from the GeneReview: Achondrogenesis Type 1B
Clinical features of achondrogenesis type 1B (ACG1B) include extremely short limbs with short fingers and toes, hypoplasia of the thorax, protuberant abdomen, and hydropic fetal appearance caused by the abundance of soft tissue relative to the short skeleton. The face is flat, the neck is short, and the soft tissue of the neck may be thickened. Death occurs prenatally or shortly after birth. [from GeneReviews]
Authors:
Sheila Unger  |  Andrea Superti-Furga   view full author information

Additional descriptions

From OMIM
The term achondrogenesis has been used to characterize the most severe forms of chondrodysplasia in humans, invariably lethal before or shortly after birth. Achondrogenesis type I is a severe chondrodystrophy characterized radiographically by deficient ossification in the lumbar vertebrae and absent ossification in the sacral, pubic and ischial bones and clinically by stillbirth or early death (Maroteaux and Lamy, 1968; Langer et al., 1969). In addition to severe micromelia, there is a disproportionately large cranium due to marked edema of soft tissues. Classification of Achondrogenesis Achondrogenesis was traditionally divided into 2 types: type I (Parenti-Fraccaro) and type II (Langer-Saldino). Borochowitz et al. (1988) suggested that achondrogenesis type I of Parenti-Fraccaro should be classified into 2 distinct disorders: type IA (ACG1A; 200600), corresponding to the cases originally published by Houston et al. (1972) and Harris et al. (1972), and type IB, corresponding to the case originally published by Fraccaro (1952). Analysis of the case reported by Parenti (1936) by Borochowitz et al. (1988) suggested the diagnosis of achondrogenesis type II, i.e., the Langer-Saldino type (200610). Type IA would be classified as lethal achondrogenesis, Houston-Harris type; type IB, lethal achondrogenesis, Fraccaro type; and type II, lethal achondrogenesis-hypochondrogenesis, Langer-Saldino type. Superti-Furga (1996) suggested that hypochondrogenesis should be considered separately from achondrogenesis type II because the phenotype can be much milder.  http://www.omim.org/entry/600972
From MedlinePlus Genetics
Achondrogenesis is a group of severe disorders that affect cartilage and bone development. These conditions are characterized by a small body, short limbs, and other skeletal abnormalities. As a result of serious health problems, infants with achondrogenesis usually die before birth, are stillborn, or die soon after birth from respiratory failure. However, some infants have lived for a short time with intensive medical support.

Infants with achondrogenesis type 2, which is sometimes called the Langer-Saldino type, have short arms and legs, a narrow chest with short ribs, and underdeveloped lungs. This condition is also associated with a lack of ossification in the spine and pelvis. Distinctive facial features include a prominent forehead, a small chin, and, in some cases, an opening in the roof of the mouth (a cleft palate). The abdomen is enlarged, and affected infants often have a condition called hydrops fetalis, in which excess fluid builds up in the body before birth.

Researchers have described at least three forms of achondrogenesis, designated as type 1A, type 1B, and type 2. The types are distinguished by their signs and symptoms, inheritance pattern, and genetic cause. However, types 1A and 1B are often hard to tell apart without genetic testing.

Achondrogenesis type 1A, which is also called the Houston-Harris type, is the least well understood of the three forms. Affected infants have extremely short limbs, a narrow chest, short ribs that fracture easily, and a lack of normal bone formation (ossification) in the skull, spine, and pelvis.

Achondrogenesis type 1B, also known as the Parenti-Fraccaro type, is characterized by extremely short limbs, a narrow chest, and a prominent, rounded abdomen. The fingers and toes are short and the feet may turn inward and upward (clubfeet). Affected infants frequently have a soft out-pouching around the belly-button (an umbilical hernia) or near the groin (an inguinal hernia).  https://medlineplus.gov/genetics/condition/achondrogenesis

Clinical features

From HPO
Micromelia
MedGen UID:
10031
Concept ID:
C0025995
Congenital Abnormality
The presence of abnormally small extremities.
Neonatal short-limb short stature
MedGen UID:
337984
Concept ID:
C1850171
Finding
A type of short-limbed dwarfism that is manifest beginning in the neonatal period.
Abdominal distention
MedGen UID:
34
Concept ID:
C0000731
Finding
Distention of the abdomen.
Inguinal hernia
MedGen UID:
6817
Concept ID:
C0019294
Finding
Protrusion of the contents of the abdominal cavity through the inguinal canal.
Umbilical hernia
MedGen UID:
9232
Concept ID:
C0019322
Anatomical Abnormality
Protrusion of abdominal contents through a defect in the abdominal wall musculature around the umbilicus. Skin and subcutaneous tissue overlie the defect.
Narrow chest
MedGen UID:
96528
Concept ID:
C0426790
Finding
Reduced width of the chest from side to side, associated with a reduced distance from the sternal notch to the tip of the shoulder.
Short ribs
MedGen UID:
98094
Concept ID:
C0426817
Finding
Reduced rib length.
Absent or minimally ossified vertebral bodies
MedGen UID:
371455
Concept ID:
C1832983
Finding
Malar flattening
MedGen UID:
347616
Concept ID:
C1858085
Finding
Underdevelopment of the malar prominence of the jugal bone (zygomatic bone in mammals), appreciated in profile, frontal view, and/or by palpation.
Hypoplastic ilia
MedGen UID:
348814
Concept ID:
C1861218
Finding
Underdevelopment of the ilium.
Respiratory insufficiency
MedGen UID:
11197
Concept ID:
C0035229
Pathologic Function
Impairment of gas exchange within the lungs secondary to a disease process, neoplasm, or trauma, possibly resulting in hypoxia, hypercarbia, or both, but not requiring intubation or mechanical ventilation. Patients are normally managed with pharmaceutical therapy, supplemental oxygen, or both.
Edema
MedGen UID:
4451
Concept ID:
C0013604
Pathologic Function
An abnormal accumulation of fluid beneath the skin, or in one or more cavities of the body.
Flat face
MedGen UID:
342829
Concept ID:
C1853241
Finding
Absence of concavity or convexity of the face when viewed in profile.
Breech presentation
MedGen UID:
654
Concept ID:
C0006157
Pathologic Function
A position of the fetus at delivery in which the fetus enters the birth canal with the buttocks or feet first.
Polyhydramnios
MedGen UID:
6936
Concept ID:
C0020224
Pathologic Function
The presence of excess amniotic fluid in the uterus during pregnancy.
Hydrops fetalis
MedGen UID:
6947
Concept ID:
C0020305
Disease or Syndrome
The abnormal accumulation of fluid in two or more fetal compartments, including ascites, pleural effusion, pericardial effusion, and skin edema.

Professional guidelines

PubMed

Dwyer E, Hyland J, Modaff P, Pauli RM
Am J Med Genet A 2010 Dec;152A(12):3043-50. doi: 10.1002/ajmg.a.33736. PMID: 21077202

Recent clinical studies

Etiology

Sillence D, Worthington S, Dixon J, Osborn R, Kozlowski K
Pediatr Radiol 1997 May;27(5):388-96. doi: 10.1007/s002470050154. PMID: 9133349

Diagnosis

Freisinger P, Stanescu V, Jacob B, Cohen-Solal L, Maroteaux P, Bonaventure J
Am J Med Genet 1994 Feb 15;49(4):439-46. doi: 10.1002/ajmg.1320490418. PMID: 8160740
Superti-Furga A
Am J Hum Genet 1994 Dec;55(6):1137-45. PMID: 7977372Free PMC Article

Prognosis

Dwyer E, Hyland J, Modaff P, Pauli RM
Am J Med Genet A 2010 Dec;152A(12):3043-50. doi: 10.1002/ajmg.a.33736. PMID: 21077202
Hästbacka J, Superti-Furga A, Wilcox WR, Rimoin DL, Cohn DH, Lander ES
Am J Hum Genet 1996 Feb;58(2):255-62. PMID: 8571951Free PMC Article

Clinical prediction guides

Dwyer E, Hyland J, Modaff P, Pauli RM
Am J Med Genet A 2010 Dec;152A(12):3043-50. doi: 10.1002/ajmg.a.33736. PMID: 21077202
Corsi A, Riminucci M, Fisher LW, Bianco P
Arch Pathol Lab Med 2001 Oct;125(10):1375-8. doi: 10.5858/2001-125-1375-ATI. PMID: 11570921
Sillence D, Worthington S, Dixon J, Osborn R, Kozlowski K
Pediatr Radiol 1997 May;27(5):388-96. doi: 10.1007/s002470050154. PMID: 9133349
Hästbacka J, Superti-Furga A, Wilcox WR, Rimoin DL, Cohn DH, Lander ES
Am J Hum Genet 1996 Feb;58(2):255-62. PMID: 8571951Free PMC Article
Superti-Furga A
Am J Hum Genet 1994 Dec;55(6):1137-45. PMID: 7977372Free PMC Article

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