Simpson-Golabi-Behmel (SGB) Syndrome Type 1 is a rare X-linked condition with macrosomia.


Chromosome: X

Location: Xq26.2

Genes affected: GPC3 (more common) or GPC4

Proteins: glypican-3 or glypican-4


Inheritance: X-linked


Clinical features:

(1) macrosomia

(2) macrocephaly

(3) ocular hypertelorism, epicanthal folds, and downslanting palpebral fissures

(4) large mouth (macrostomia)

(5) macroglossia

(6) dental malocclusion

(7) cleft lip, submucous cleft palate with bifid uvula, high arched palate

(8) micrognathia in neonates becoming macrognathia with age

(9) esotropia, cataracts, coloboma of the optic disc

(10) wide nasal bridge and anteverted nares in infants

(11) deep furrow in the middle of the tongue and/or midline groove of the lower lip

(12) congenital heart disease

(13) cardiac conduction defects

(14) diaphragmatic hernia

(15) nephromegaly and renal dysplasia

(16) cryptorchidism and/or hypospadias

(17) abnormal fingers (brachydactyly, cutaneous syndactyly, polydactyly

(18) normal intelligence to severe intellectual delay

(19) thymic hypoplasia and generalized lymphoid atrophy

(20) diastasis recti and/or umbilical hernia

(21) supernumerary nipples

(22) congenital hip dislocation

(23) vertebral fusion

(24) scoliosis

(25) rib anomalies

(26) hypoglycemia

(27) hearing and speech difficulties

(28) sleep apnea

(29) hypotonia

(30) furrowed skin over the glabella

(31) variable minor anomalies of the ears


Patients have an increased risk for certain tumors:

(1) Wilms tumor

(2) hepatoblastoma

(3) hepatocellular carcinoma

(4) adrenal neuroblastoma

(5) gonadoblastoma


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