Necropsy findings in a child with FG syndrome

A new X-linked syndrome with agenesis of the corpus callosum, mental retardation, coloboma, micrognathia, and a mutation in the Alpha 4 gene at Xq13

We describe two brothers with a unique pattern of malformations that includes coloboma (iris, optic nerve), high forehead, severe retrognathia, mental retardation, and agenesis of the corpus callosum (ACC). Both boys have low-set cupped ears with sensorineural hearing loss, normal phallus, pectus excavatum, scoliosis, and short stature. One brother had choanal atresia and cardiac defects consisting of ventricular septal defect (VSD) and patent ductus arteriosus (PDA) which resolved spontaneously. Differential diagnosis between a number of clinical entities was considered, however, because ACC and the distinctive facial features were reminiscent of FG syndrome, DNA was analyzed for markers linked to the FGS1 locus at Xq13-q21. Notably, the brothers were concordant for markers spanning this presumed FG region, and in both we have identified adjacent alterations (-57delT and T-55A) in the Alpha 4 gene located within this interval. Alpha 4 is a regulatory subunit of the major cellular phosphatase, PP2A, that has recently been shown to interact with MID1, the product of the gene mutated in X-linked Opitz GBBB syndrome. The double nucleotide change identified in this family was not observed in 410 control chromosomes, suggesting that it may be a pathogenetic change. Altered expression of Alpha 4, through either a change in translational efficiency, mRNA stability or splicing, could explain the clinical phenotype in these boys and the phenotypic overlap with Opitz GBBB syndrome.

Fragile X mutation and FG syndrome-like phenotype

We present data on 4 mentally retarded brothers, 2 of whom were dizygotic twins with congenital hypotonia, constipation, head size disproportionately large for length or height, and a combination of minor anomalies suggestive of FG syndrome. These brothers have a mentally retarded full sister with similar minor anomalies and an older half-brother with the Martin-Bell syndrome. The mother is mentally retarded; 4 of 7 individuals are positive for fragile X, but all have a CGG expansion ranging from 0.2-2 to 4 kb. Although the phenotype is not completely typical of the FG syndrome and the coincidence of the FMR1 mutation and segregation of the MCA/MR phenotype are highly unlikely, the FMR1 mutation may affect morphogenesis more extensively and differently than the Martin-Bell syndrome does to effect an FG syndromelike phenotype in certain families. This phenotype does not appear to be a contiguous gene syndrome, but an effect of the FMR1 mutation on an adjacent gene must be considered.

Stratton-Parker syndrome: confirmation of a new entity

Recently, Stratton and Parker [Am J Med Genet 32:169-173, 1989] reported on a child with a previously undescribed combination of growth hormone deficiency, wormian bones, dextrocardia, brachycamptodactyly, and other midline defects. We report on another patient with similar clinical signs.

Cerebral malformation, seizures, hypertrichosis, distinct face, claw hands, and overlapping fingers in sibs of both sexes

We report on sibs of both sexes with a multiple malformation syndrome of cerebral malformation, seizures, hypertrichosis, distinct face, claw hands, and overlapping fingers. The older boy died in a tonic extension spasm at age 4 months. When discharged, the younger girl was 3.5 months old. This appears to be an autosomal recessive syndrome which to our knowledge has not been described before.

Language and development in FG syndrome with callosal agenesis

The FG syndrome is characterized by unusual facies, sudden infant death, developmental delay, and abnormalities of the cardiac, gastrointestinal, and central nervous systems. No longitudinal data on development in surviving patients are currently available. Serial evaluations of a patient with FG syndrome, whose sole central nervous system anomaly was agenesis of the corpus callosum, showed a consistent pattern over time. Specific language impairments in syntactic and pragmatic-semantic areas are emerging. These findings represent the first detailed data on which expectations for children with the FG syndrome can be based. The findings also fit theoretical constructs on the function of the corpus callosum and may therefore be generalized to provide expectations for other patients with isolated agenesis of the corpus callosum. Given the information gained from this case, it is clear that language intervention/consultation should be a pivotal service for such children, and that the speech-language pathologist should play a role in the development of an integrated educational services plan.

FG syndrome update 1988: note of 5 new patients and bibliography

At the eve of its mapping, the pre-molecular picture of the FG syndrome is heavily biased towards the severe end of the phenotypic spectrum because present knowledge is largely based on propositi. It is an X-linked, incompletely recessive, complexly pleiotropic syndrome with considerably variable expressivity. Though a true multiple congenital anomalies/mental retardation (MCA/MR) syndrome, severe malformations are uncommon and involve mostly the anus (60%) and non-colonic GI defects (33%), hypospadias (25%), cleft palate (6%), rarely a congenital heart defect. The complex CNS dysfunctions of congenital hypotonia and all of its sequelae, MR, and occasional seizures, must be attributed to a developmental CNS defect which is rarely demonstrated at pre-mortem, and which is known to involve agenesis of the corpus callosum in some 25% of appropriately studied patients (mostly propositi). Thus, the diagnosis is largely made on a specific constellation of minor anomalies and mild malformations in a hypotonic boy with severe constipation and a very characteristic facial appearance and behavioral phenotype. In about 1/3 of cases, carrier manifestations may be detected physically. New hemizygote manifestations seen in this review of 5 new patients include abnormal eruption of teeth, diastasis between upper central incisors, apparent gynecomastia, cleft lip, and nasolacrimal and helicine fistulae. Only a half hundred or so FG syndrome patients are known, but we suspect the syndrome is much more common than realized, and because of the unfortunate recurrence risk potential, deserves careful consideration in every appropriate case. RFLP mapping studies are urged in order to aid diagnosis of "mild" cases, and prenatal and carrier detection.

Callosal defect, microcephaly, severe mental retardation, and other anomalies in three sibs

This study concerns an apparently lethal and previously undescribed syndrome of hypoplastic corpus callosum, microcephaly, severe mental retardation, preauricular skin tag, camptodactyly, growth retardation, and recurrent bronchopneumonia. This combination of anomalies is probably inherited as an autosomal recessive trait. A brief literature review of the anomalies or syndromes associated with callosal defects is discussed.

FG syndrome

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