Pathologic macrocephaly may be caused by congenital anatomic abnormalities, genetic conditions, or by environmental events.Many genetic conditions are associated with macrocephaly, including familial macrocephaly related to the holgate gene, autism, PTEN mutations such as Cowden disease, neurofibromatosis type 1, and tuberous sclerosis; overgrowth syndromes such as Sotos syndrome (cerebral gigantism), Weaver syndrome, Simpson–Golabi–Behmel syndrome (bulldog syndrome), and macrocephaly-capillary malformation (M-CMTC) syndrome; neurocardiofacial-cutaneous syndromes such as Noonan syndrome, Costello syndrome, Gorlin syndrome, (also known as Basal Cell Nevus Syndrome) and cardiofaciocutaneous syndrome; Fragile X syndrome; leukodystrophies (brain white matter degeneration) such as Alexander disease, Canavan disease, and megalencephalic leukoencephalopathy with subcortical cysts; and glutaric aciduria type 1 and D-2-hydroxyglutaric aciduria.At one end of the genetic spectrum, duplications of chromosomes have been found to be related to autism and macrocephaly; at the other end, deletions of chromosomes have been found to be related to schizophrenia and microcephaly.Environmental events associated with macrocephaly include infection, neonatal intraventricular hemorrhage (bleeding within the infant brain), subdural hematoma (bleeding beneath the outer lining of the brain), subdural effusion (collection of fluid beneath the outer lining of the brain), and arachnoid cysts (cysts on the brain surface).In research, cranial height or brain imaging may be used to determine intracranial volume more accurately.
If excess fluid is found between the ventricle spaces in the brain then surgery will be needed. Associated syndromes
Below is a list of syndromes associated with macrocephaly that are noted in Signs and Symptoms of Genetic Conditions: A Handbook. Include multiple major and or minor anomalies
Acrocallosal syndrome
Apert syndrome
Bannayan–Riley–Ruvalcaba syndrome
Cardiofaciocutaneous syndrome
Chromosome 14 - maternal disomy
Chromosome 22qter deletion
Cleidocranial dysostosis
Costello syndrome
Encephalocraniocutaneous lipomatosis
FG syndrome
Hallermann–Streiff syndrome
Hydrolethalus syndrome
Hypomelanosis syndrome
Hypomelanosis of Ito
Kelvin Peter anomaly plus syndrome
Lujan–Fryns syndrome
Macrocephaly-CM (MCAP)
Marshall–Smith syndrome
Neuhauser megalocornea/MR syndrome
Neurofibromatosis type I
Nevoid basal-cell carcinoma syndrome
Noonan syndrome
Ocular-ectodermal syndrome
Osteopathia striata - cranial sclerosis
Perlman syndrome
Robinow syndrome
Simpson–Golabi–Behmel syndrome
Sotos syndrome
Sturge–Weber syndrome
Weaver syndrome
Wiedemann–Rautenstrauch syndrome
3C syndrome

Secondary to a metabolic disorder
Glutaric aciduria type II
GM1 gangliosidosis
Hunter syndrome
Hurler syndrome
MPS VII
Sanfilippo syndrome
Zellweger syndrome

Associated with a skeletal dysplasia
Achondroplasia
Campomelic dysplasia
Craniodiaphyseal dysplasia
Craniometaphyseal dysplasia
Hypochondrogenesis
Hypochondroplasia
Kenny-Caffey syndrome
Kniest dysplasia
Lenz–Majewski syndrome
Osteogenesis imperfecta III
Osteopetrosis, autosomal recessive form
Schneckenbecken dysplasia
Sclerosteosis
Short rib syndrome, beemer-langer type
Short rib-polydactyly 2 (majewski type)
Spondyloepiphyseal dysplasia congenita
Thanatophoric dysplasia

With no obvious physical findings
Alexander disease
Canavan disease
Cobalamin deficiency (combined methylmalonic aciduria and homocystinuria)
Dandy–Walker malformation
Glutaric aciduria type 1
L-2-hydroxyglutaric aciduria
Megalencephalic leukoencephalopathy with subcortical cysts
Osteogenesis imperfecta IV
Osteopathia striata-cranial sclerosis
Periventricular heterotopia
Sandhoff disease
Tay–Sachs disease

See also
Microcephaly
Megalencephaly
Hydrocephalus

References
External links
GeneReviews/NCBI/NIH/UW entry on PTEN Hamartoma Tumor Syndrome (PHTS)
GeneReviews/NCBI/NIH/UW entry on 9q22.3 Microdeletion