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FG syndrome 2(FGS2)

MedGen UID:
337461
Concept ID:
C1845902
Disease or Syndrome
Synonym: FGS2
 
Gene (location): FLNA (Xq28)
 
Monarch Initiative: MONDO:0010297
OMIM®: 300321

Definition

Although the phenotypic spectrum and severity of FG syndrome is wide, the cardinal features include congenital hypotonia, delayed speech development, relative macrocephaly, dysmorphic facies, and anal anomalies or severe constipation (Unger et al., 2007). For a general phenotypic description and a discussion of genetic heterogeneity of FG syndrome, see FGS1 (305450). [from OMIM]

Additional description

From MedlinePlus Genetics
Additional features seen in some people with FG syndrome include widely set eyes (hypertelorism), an upswept frontal hairline, and a large head compared to body size (relative macrocephaly). Other health problems have also been reported, including heart defects, seizures, undescended testes (cryptorchidism) in males, and a soft out-pouching in the lower abdomen (an inguinal hernia).

The physical features of FG syndrome include weak muscle tone (hypotonia), broad thumbs, and wide first (big) toes. Abnormalities of the tissue connecting the left and right halves of the brain (the corpus callosum) are also common. Most affected individuals have constipation, and many have abnormalities of the anus such as an obstruction of the anal opening (imperforate anus). People with FG syndrome also tend to have a distinctive facial appearance including small, underdeveloped ears; a tall, prominent forehead; and outside corners of the eyes that point downward (down-slanting palpebral fissures).

FG syndrome affects intelligence and behavior. Almost everyone with the condition has intellectual disability, which ranges from mild to severe. Affected individuals tend to be friendly, inquisitive, and hyperactive, with a short attention span. Compared to people with other forms of intellectual disability, their socialization and daily living skills are strong, while verbal communication and language skills tend to be weaker.

FG syndrome is a genetic condition that affects many parts of the body and occurs almost exclusively in males. "FG" represents the surname initials of the first family diagnosed with the disorder.  https://medlineplus.gov/genetics/condition/fg-syndrome

Clinical features

From HPO
Broad hallux
MedGen UID:
401165
Concept ID:
C1867131
Finding
Visible increase in width of the hallux without an increase in the dorso-ventral dimension.
Decreased body weight
MedGen UID:
1806755
Concept ID:
C5574742
Finding
Abnormally low body weight.
Constipation
MedGen UID:
1101
Concept ID:
C0009806
Sign or Symptom
Infrequent or difficult evacuation of feces.
Protruding ear
MedGen UID:
343309
Concept ID:
C1855285
Finding
Angle formed by the plane of the ear and the mastoid bone greater than the 97th centile for age (objective); or, outer edge of the helix more than 2 cm from the mastoid at the point of maximum distance (objective).
Underdeveloped superior crus of antihelix
MedGen UID:
866835
Concept ID:
C4021189
Anatomical Abnormality
Decreased protrusion of the superior crus relative to the prominence of a normal antihelix stem.
Delayed speech and language development
MedGen UID:
105318
Concept ID:
C0454644
Finding
A degree of language development that is significantly below the norm for a child of a specified age.
Neonatal hypotonia
MedGen UID:
412209
Concept ID:
C2267233
Disease or Syndrome
Muscular hypotonia (abnormally low muscle tone) manifesting in the neonatal period.
Prominent forehead
MedGen UID:
373291
Concept ID:
C1837260
Finding
Forward prominence of the entire forehead, due to protrusion of the frontal bone.
Large forehead
MedGen UID:
326962
Concept ID:
C1839783
Finding
Frontal upsweep of hair
MedGen UID:
452910
Concept ID:
C1185616
Finding
Upward and/or sideward growth of anterior hair.

Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews,  VClinVar  

Recent clinical studies

Etiology

Shah A, Bapna M, Al-Saif H, Li R, Couser NL
Ophthalmic Genet 2022 Feb;43(1):126-129. Epub 2021 Oct 20 doi: 10.1080/13816810.2021.1989601. PMID: 34670449
Graham JM Jr, Visootsak J, Dykens E, Huddleston L, Clark RD, Jones KL, Moeschler JB, Opitz JM, Morford J, Simensen R, Rogers RC, Schwartz CE, Friez MJ, Stevenson RE
Am J Med Genet A 2008 Dec 1;146A(23):3011-7. doi: 10.1002/ajmg.a.32553. PMID: 18973276Free PMC Article
Smith JF, Wayment RO, Cartwright PC, Snow BW, Opitz JM
J Urol 2007 Aug;178(2):656-9. Epub 2007 Jun 15 doi: 10.1016/j.juro.2007.04.007. PMID: 17574621

Diagnosis

Bhatti GK, Khullar N, Sidhu IS, Navik US, Reddy AP, Reddy PH, Bhatti JS
Metab Brain Dis 2021 Aug;36(6):1119-1134. Epub 2021 Apr 21 doi: 10.1007/s11011-021-00739-y. PMID: 33881724Free PMC Article
Li D, Strong A, Shen KM, Cassiman D, Van Dyck M, Linhares ND, Valadares ER, Wang T, Pena SDJ, Jaeken J, Vergano S, Zackai E, Hing A, Chow P, Ganguly A, Scholz T, Bierhals T, Philipp D, Hakonarson H, Bhoj E
Genet Med 2021 Apr;23(4):637-644. Epub 2020 Nov 27 doi: 10.1038/s41436-020-01031-7. PMID: 33244166
Graham JM Jr, Schwartz CE
Am J Med Genet A 2013 Nov;161A(11):2734-40. Epub 2013 Oct 10 doi: 10.1002/ajmg.a.36183. PMID: 24123922Free PMC Article
Graham JM Jr, Clark RD, Moeschler JB, Rogers RC
Am J Med Genet C Semin Med Genet 2010 Nov 15;154C(4):477-85. doi: 10.1002/ajmg.c.30284. PMID: 20981778Free PMC Article
Graham JM Jr, Visootsak J, Dykens E, Huddleston L, Clark RD, Jones KL, Moeschler JB, Opitz JM, Morford J, Simensen R, Rogers RC, Schwartz CE, Friez MJ, Stevenson RE
Am J Med Genet A 2008 Dec 1;146A(23):3011-7. doi: 10.1002/ajmg.a.32553. PMID: 18973276Free PMC Article

Therapy

Maia N, Ibarluzea N, Misra-Isrie M, Koboldt DC, Marques I, Soares G, Santos R, Marcelis CLM, Keski-Filppula R, Guitart M, Gabau Vila E, Lehman A, Hickey S, Mori M, Terhal P, Valenzuela I, Lasa-Aranzasti A, Cueto-González AM, Chhouk BH, Yeh RC, Neil JE, Abu-Libde B, Kleefstra T, Elting MW, Császár A, Kárteszi J, Bessenyei B, van Bokhoven H, Jorge P, van Hagen JM, de Brouwer APM
Am J Med Genet A 2023 Jan;191(1):135-143. Epub 2022 Oct 22 doi: 10.1002/ajmg.a.63004. PMID: 36271811Free PMC Article

Prognosis

Chanchani SR, Xie H, Sekhon G, Melikishvili AM, Moyer Harasink S, Pall H, Giampietro PF
Mol Genet Genomic Med 2020 Mar;8(3):e1078. Epub 2020 Jan 17 doi: 10.1002/mgg3.1078. PMID: 31951325Free PMC Article
Dunn P, Prigatano GP, Szelinger S, Roth J, Siniard AL, Claasen AM, Richholt RF, De Both M, Corneveaux JJ, Moskowitz AM, Balak C, Piras IS, Russell M, Courtright AL, Belnap N, Rangasamy S, Ramsey K, Opitz JM, Craig DW, Narayanan V, Huentelman MJ, Schrauwen I
Am J Med Genet A 2017 Mar;173(3):611-617. Epub 2017 Jan 31 doi: 10.1002/ajmg.a.38069. PMID: 28139025
Prontera P, Ottaviani V, Rogaia D, Isidori I, Mencarelli A, Malerba N, Cocciadiferro D, Rolph P, Stangoni G, Vulto-van Silfhout A, Merla G
Am J Med Genet A 2016 Sep;170(9):2377-82. Epub 2016 Jun 17 doi: 10.1002/ajmg.a.37805. PMID: 27312080
Neri C, Moser K, Pysher TJ, Boettger DR, Neri G, Opitz JM
Fetal Pediatr Pathol 2011;30(2):71-6. doi: 10.3109/15513815.2011.520259. PMID: 21391746
Smith JF, Wayment RO, Cartwright PC, Snow BW, Opitz JM
J Urol 2007 Aug;178(2):656-9. Epub 2007 Jun 15 doi: 10.1016/j.juro.2007.04.007. PMID: 17574621

Clinical prediction guides

Chanchani SR, Xie H, Sekhon G, Melikishvili AM, Moyer Harasink S, Pall H, Giampietro PF
Mol Genet Genomic Med 2020 Mar;8(3):e1078. Epub 2020 Jan 17 doi: 10.1002/mgg3.1078. PMID: 31951325Free PMC Article
Dunn P, Prigatano GP, Szelinger S, Roth J, Siniard AL, Claasen AM, Richholt RF, De Both M, Corneveaux JJ, Moskowitz AM, Balak C, Piras IS, Russell M, Courtright AL, Belnap N, Rangasamy S, Ramsey K, Opitz JM, Craig DW, Narayanan V, Huentelman MJ, Schrauwen I
Am J Med Genet A 2017 Mar;173(3):611-617. Epub 2017 Jan 31 doi: 10.1002/ajmg.a.38069. PMID: 28139025
Prontera P, Ottaviani V, Rogaia D, Isidori I, Mencarelli A, Malerba N, Cocciadiferro D, Rolph P, Stangoni G, Vulto-van Silfhout A, Merla G
Am J Med Genet A 2016 Sep;170(9):2377-82. Epub 2016 Jun 17 doi: 10.1002/ajmg.a.37805. PMID: 27312080
Lesca G, Moizard MP, Bussy G, Boggio D, Hu H, Haas SA, Ropers HH, Kalscheuer VM, Des Portes V, Labalme A, Sanlaville D, Edery P, Raynaud M, Lespinasse J
Am J Med Genet A 2013 Dec;161A(12):3063-71. Epub 2013 Aug 16 doi: 10.1002/ajmg.a.36162. PMID: 24039113
Short KM, Hopwood B, Yi Z, Cox TC
BMC Cell Biol 2002;3:1. Epub 2002 Jan 4 doi: 10.1186/1471-2121-3-1. PMID: 11806752Free PMC Article

Recent systematic reviews

Shah A, Bapna M, Al-Saif H, Li R, Couser NL
Ophthalmic Genet 2022 Feb;43(1):126-129. Epub 2021 Oct 20 doi: 10.1080/13816810.2021.1989601. PMID: 34670449

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