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Bardet-Biedl syndrome 2(BBS2)

MedGen UID:
422453
Concept ID:
C2936863
Disease or Syndrome
Synonym: BBS2
 
Gene (location): BBS2 (16q13)
 
Monarch Initiative: MONDO:0014432
OMIM®: 615981

Definition

BBS2 is an autosomal recessive ciliopathy characterized by retinal degeneration, polydactyly, renal disease, hypogonadism, obesity, dysmorphic features, and variable degrees of cognitive impairment (Innes et al., 2010). Mutation in the BBS2 gene is the third most frequent cause of BBS, accounting for approximately 8% of cases (Zaghloul and Katsanis, 2009). For a general phenotypic description and a discussion of genetic heterogeneity of Bardet-Biedl syndrome, see BBS1 (209900). [from OMIM]

Clinical features

From HPO
Polyuria
MedGen UID:
19404
Concept ID:
C0032617
Sign or Symptom
An increased rate of urine production.
Chordee
MedGen UID:
66363
Concept ID:
C0221182
Congenital Abnormality
Ventral, lateral, or ventrolateral bowing of the shaft and glans penis of more than 30 degrees.
Dilatation of the renal pelvis
MedGen UID:
574571
Concept ID:
C0341676
Disease or Syndrome
The presence of dilatation of the renal pelvis.
Hypospadias
MedGen UID:
163083
Concept ID:
C0848558
Congenital Abnormality
Abnormal position of urethral meatus on the ventral penile shaft (underside) characterized by displacement of the urethral meatus from the tip of the glans penis to the ventral surface of the penis, scrotum, or perineum.
Chronic kidney disease
MedGen UID:
473458
Concept ID:
C1561643
Disease or Syndrome
Functional anomaly of the kidney persisting for at least three months.
External genital hypoplasia
MedGen UID:
344478
Concept ID:
C1855333
Finding
Underdevelopment of part or all of the external reproductive organs.
Multicystic kidney dysplasia
MedGen UID:
811388
Concept ID:
C3714581
Disease or Syndrome
Multicystic dysplasia of the kidney is characterized by multiple cysts of varying size in the kidney and the absence of a normal pelvicaliceal system. The condition is associated with ureteral or ureteropelvic atresia, and the affected kidney is nonfunctional.
Micropenis
MedGen UID:
1633603
Concept ID:
C4551492
Congenital Abnormality
Abnormally small penis. At birth, the normal penis is about 3 cm (stretched length from pubic tubercle to tip of penis) with micropenis less than 2.0-2.5 cm.
Postaxial hand polydactyly
MedGen UID:
609221
Concept ID:
C0431904
Congenital Abnormality
Supernumerary digits located at the ulnar side of the hand (that is, on the side with the fifth finger).
Postaxial foot polydactyly
MedGen UID:
384489
Concept ID:
C2112129
Finding
Polydactyly of the foot most commonly refers to the presence of six toes on one foot. Postaxial polydactyly affects the lateral ray and the duplication may range from a well-formed articulated digit to a rudimentary digit.
3-4 finger cutaneous syndactyly
MedGen UID:
868712
Concept ID:
C4023115
Congenital Abnormality
A soft tissue continuity in the A/P axis between fingers 3 and 4.
Primary dilated cardiomyopathy
MedGen UID:
2880
Concept ID:
C0007193
Disease or Syndrome
Familial dilated cardiomyopathy is a genetic form of heart disease. It occurs when heart (cardiac) muscle becomes thin and weakened in at least one chamber of the heart, causing the open area of the chamber to become enlarged (dilated). As a result, the heart is unable to pump blood as efficiently as usual. To compensate, the heart attempts to increase the amount of blood being pumped through the heart, leading to further thinning and weakening of the cardiac muscle. Over time, this condition results in heart failure.\n\nIt usually takes many years for symptoms of familial dilated cardiomyopathy to cause health problems. They typically begin in mid-adulthood, but can occur at any time from infancy to late adulthood. Signs and symptoms of familial dilated cardiomyopathy can include an irregular heartbeat (arrhythmia), shortness of breath (dyspnea), extreme tiredness (fatigue), fainting episodes (syncope), and swelling of the legs and feet. In some cases, the first sign of the disorder is sudden cardiac death. The severity of the condition varies among affected individuals, even in members of the same family.
Atrial septal defect
MedGen UID:
6753
Concept ID:
C0018817
Congenital Abnormality
Atrial septal defect (ASD) is a congenital abnormality of the interatrial septum that enables blood flow between the left and right atria via the interatrial septum.
Hypertensive disorder
MedGen UID:
6969
Concept ID:
C0020538
Disease or Syndrome
The presence of chronic increased pressure in the systemic arterial system.
Bicuspid aortic valve
MedGen UID:
57436
Concept ID:
C0149630
Congenital Abnormality
Aortic valve disease-2 (AOVD2) is characterized by bicuspid aortic valve (BAV) and dilation of the ascending aorta. Calcification of the valve and the aorta has been observed, and some patients exhibit coarctation of the aorta (Tan et al., 2012; Luyckx et al., 2019; Park et al., 2019). For a general phenotypic description and a discussion of genetic heterogeneity of aortic valve disease, see AOVD1 (109730).
Fetal growth restriction
MedGen UID:
4693
Concept ID:
C0015934
Pathologic Function
An abnormal restriction of fetal growth with fetal weight below the tenth percentile for gestational age.
Obesity
MedGen UID:
18127
Concept ID:
C0028754
Disease or Syndrome
Accumulation of substantial excess body fat.
Polydipsia
MedGen UID:
43214
Concept ID:
C0085602
Sign or Symptom
Excessive thirst manifested by excessive fluid intake.
Hyperactivity
MedGen UID:
98406
Concept ID:
C0424295
Finding
Hyperactivity is a condition characterized by constant and unusually high levels of activity, even in situations where it is deemed inappropriate.
Global developmental delay
MedGen UID:
107838
Concept ID:
C0557874
Finding
A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age.
Intellectual disability
MedGen UID:
811461
Concept ID:
C3714756
Mental or Behavioral Dysfunction
Intellectual disability, previously referred to as mental retardation, is characterized by subnormal intellectual functioning that occurs during the developmental period. It is defined by an IQ score below 70.
Diabetes mellitus
MedGen UID:
8350
Concept ID:
C0011849
Disease or Syndrome
A group of abnormalities characterized by hyperglycemia and glucose intolerance.
Dental crowding
MedGen UID:
11850
Concept ID:
C0040433
Finding
Changes in alignment of teeth in the dental arch
Round face
MedGen UID:
116087
Concept ID:
C0239479
Finding
The facial appearance is more circular than usual as viewed from the front.
Bulbous nose
MedGen UID:
66013
Concept ID:
C0240543
Finding
Increased volume and globular shape of the anteroinferior aspect of the nose.
Downslanted palpebral fissures
MedGen UID:
98391
Concept ID:
C0423110
Finding
The palpebral fissure inclination is more than two standard deviations below the mean.
Short palpebral fissure
MedGen UID:
98067
Concept ID:
C0423112
Finding
Distance between the medial and lateral canthi is more than 2 SD below the mean for age (objective); or, apparently reduced length of the palpebral fissures.
Short neck
MedGen UID:
99267
Concept ID:
C0521525
Finding
Diminished length of the neck.
Thin vermilion border
MedGen UID:
108294
Concept ID:
C0578038
Finding
Height of the vermilion of the medial part of the lip more than 2 SD below the mean, or apparently reduced height of the vermilion of the lip in the frontal view. The vermilion is the red part of the lips (and confusingly, the vermilion itself is also often referred to as being equivalent the lips).
Smooth philtrum
MedGen UID:
222980
Concept ID:
C1142533
Finding
Flat skin surface, with no ridge formation in the central region of the upper lip between the nasal base and upper vermilion border.
Depressed nasal bridge
MedGen UID:
373112
Concept ID:
C1836542
Finding
Posterior positioning of the nasal root in relation to the overall facial profile for age.
Hypogonadism
MedGen UID:
5711
Concept ID:
C0020619
Disease or Syndrome
A decreased functionality of the gonad.
Night blindness
MedGen UID:
10349
Concept ID:
C0028077
Disease or Syndrome
Inability to see well at night or in poor light.
Retinal degeneration
MedGen UID:
48432
Concept ID:
C0035304
Finding
A nonspecific term denoting degeneration of the retinal pigment epithelium and/or retinal photoreceptor cells.
Peripheral visual field loss
MedGen UID:
116124
Concept ID:
C0241688
Finding
Loss of peripheral vision with retention of central vision, resulting in a constricted circular tunnel-like field of vision.
Deeply set eye
MedGen UID:
473112
Concept ID:
C0423224
Finding
An eye that is more deeply recessed into the plane of the face than is typical.
Moderate myopia
MedGen UID:
939834
Concept ID:
C4315867
Disease or Syndrome
A moderate form of myopia with refractive error of between -3.00 and -6.00 diopters.
Rod-cone dystrophy
MedGen UID:
1632921
Concept ID:
C4551714
Disease or Syndrome
An inherited retinal disease subtype in which the rod photoreceptors appear to be more severely affected than the cone photoreceptors. Typical presentation is with nyctalopia (due to rod dysfunction) followed by loss of mid-peripheral field of vision, which gradually extends and leaves many patients with a small central island of vision due to the preservation of macular cones.
Ultra-low vision with retained light projection
MedGen UID:
1701453
Concept ID:
C5139242
Finding
Ultra-low vision but with retained ability to perceive the difference between light and dark. Also when light is projected in each of the four quadrants of the visual field, the individual is able to correctly identify the origin of the light stimulus.

Professional guidelines

PubMed

Rao PV, Lu X, Pattee P, Turner M, Nandgaonkar S, Paturi BT, Roberts CT Jr, Nagalla SR
J Assoc Physicians India 2005 Jun;53:521-6. PMID: 16121806

Curated

Slavotinek A, Beales P
Eur J Hum Genet 2011 Mar;19(3) Epub 2010 Dec 8 doi: 10.1038/ejhg.2010.199. PMID: 21150877Free PMC Article

Recent clinical studies

Etiology

Rao PV, Lu X, Pattee P, Turner M, Nandgaonkar S, Paturi BT, Roberts CT Jr, Nagalla SR
J Assoc Physicians India 2005 Jun;53:521-6. PMID: 16121806

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