Germline and mosaic mutations of FLN1 in men with periventricular heterotopia.
OBJECTIVE
To describe the phenotypic spectrum and genetics of periventricular nodular heterotopia (PNH) caused by FLN1 mutations in four men.


BACKGROUND
X-linked PNH caused by FLN1 mutations (MIM #300049) implies prenatal or early postnatal lethality in boys and 50% recurrence risk in daughters of affected women.


METHODS
Clinical examination, cognitive testing, MRI, and mutation analysis (denaturing high-performance liquid chromatography and direct sequencing) on blood lymphocytes and single hair roots were performed for nine affected individuals, including three men. Neuropathologic study of the brain was performed for an affected boy.


RESULTS
In two families, missense mutations were transmitted from mother to son (Met102Val) and from father to daughter (Ser149Phe), causing mild phenotypes in both genders, including unilateral PNH. In a third family, a man was mosaic for an A>G substitution (intron 11 acceptor splice site) on leukocyte DNA and hair roots (mutant = 42% and 69%). Single hair root analysis confirmed that the mutation was not present in all ectodermal derivative cells. A healthy daughter had inherited the X chromosome from her father's wild-type germinal cell population. In the fourth family, an eight-base deletion (AGGAGGTG, intron 25 donor splice site) led to early deaths of boys. Postmortem study in a newborn boy revealed PNH and cardiovascular, genitourinary, and gut malformations.


CONCLUSIONS
Periventricular nodular heterotopia caused by FLN1 mutations in men has a wide clinical spectrum and is caused by different genetic mechanisms, including somatic mosaicism. Mutation analysis of FLN1 should support genetic counseling in men with periventricular nodular heterotopia.
Guerrini
R
R
Division of Child Neurology and Psychiatry, University of Pisa and IRCCS Fondazione Stella Maris, via dei Giacinti 2, 56018 Calambrone Pisa, Italy. renzo.guerrini@inpe.unipi.it
Mei
D
D
Sisodiya
S
S
Sicca
F
F
Harding
B
B
Takahashi
Y
Y
Dorn
T
T
Yoshida
A
A
Campistol
J
J
Krämer
G
G
Moro
F
F
Dobyns
W B
WB
Parrini
E
E
D000015:Abnormalities, Multiple / Q000235:genetics; D001927:Brain Diseases / Q000235:genetics*; D002465:Cell Movement / Q000235:genetics; D002552:Cerebral Ventricles / Q000002:abnormalities*; D002675:Child, Preschool; D002828:Choristoma / Q000235:genetics*; D041321:Chromosomes, Human, X / Q000235:genetics*; D002946:Cisterna Magna / Q000002:abnormalities*; D003285:Contractile Proteins / Q000172:deficiency / Q000235:genetics*; D004252:DNA Mutational Analysis; D004303:Dosage Compensation, Genetic; D005260:Female; D064448:Filamins; D005804:Genes, Lethal; D040181:Genetic Diseases, X-Linked / Q000175:diagnosis / Q000235:genetics*; D018095:Germ-Line Mutation; D018859:Hair Follicle / Q000737:chemistry; D006801:Humans; D007231:Infant, Newborn; D007438:Introns / Q000235:genetics; D008297:Male; D008840:Microfilament Proteins / Q000172:deficiency / Q000235:genetics*; D008875:Middle Aged; D009030:Mosaicism; D020125:Mutation, Missense; D009474:Neurons / Q000473:pathology; D010375:Pedigree; D010641:Phenotype; D017354:Point Mutation; D022821:RNA Splice Sites / Q000235:genetics; D017384:Sequence Deletion
D003285:Contractile Proteins; C578663:FLNA protein, human; D064448:Filamins; D008840:Microfilament Proteins; D022821:RNA Splice Sites