The following description of the clinical manifestations is based on a comprehensive review of the literature and personal observations of the moderators (unpublished data).
Alopecia
Alopecia appears to be the most distinctive feature of BABS, but it does have some variability.
• Hair is typically present at birth but is sometimes sparse and sometimes has atypical color (darker or lighter than anticipated).
• Loss of hair, if present, begins in the first few weeks of life with hair falling out in large clumps.
• Absent or sparse eyebrows and eyelashes are typically congenital.
• Some affected individuals undergo regrowth of scalp hair that usually remains sparse, although one affected individual had full, thick hair with no reported loss of hair postnatally but did have absent eyebrows and eyelashes.
Nonspecific Dysmorphic Features
Dysmorphic features have been identified in most affected individuals, but not with any discernible pattern or consistency.
Developmental Delay/Intellectual Disability
Developmental delay is evident early in life with both motor and speech delays. Walking was achieved between age 17 months and four years, although two affected individuals still had not walked when reported at ages three and five years. First words were said between ages three and six years; three affected individuals were nonverbal when reported at ages ten months, 32 months, and 16 years.
Hypotonia
Hypotonia is uniform and likely contributes to motor developmental delay.
Behavior
Attention-deficit/hyperactivity disorder (ADHD), autism, and/or aggression have been reported in six of the eleven published individuals.
• Behavioral concerns evolved in one affected individual treated with difluoromethylornithine (DFMO), resulting in a diagnosis of autism.
• It is unclear whether DFMO treatment accelerated the development of autistic symptoms which would have developed in any case (although more slowly) without treatment, or whether the treatment itself affected brain function through the alteration of polyamine levels.
Growth
Larger head circumference for age and sex is often seen. One affected individual with a normal head circumference had sagittal craniosynostosis, which has not been seen in any other reported individuals.
Macrosomia at birth has been reported; in four of five affected individuals measured, length was >95% percentile, and weight in two of five was >95% percentile. However, growth parameters tend to normalize with age: at later childhood examination, only two of eight had height >95% percentile and none had weight >95% percentile.
Gastrointestinal and Feeding
Ability to feed varies with developmental level, with some affected individuals requiring gastrostomy tube. Others can take food by mouth. Constipation has been seen and may be related to hypotonia.
Skin Findings
Skin findings including keratosis pilaris, recurrent follicular cysts (particularly on the back, axilla, and posterior of head), and dry skin have been observed in childhood. Cysts were noted in the first few years of life and resolved with the first two patients receiving DFMO treatment. The third patient receiving DFMO treatment did not have a history of cysts.
Seizures
Seizures seen in one individual, at age 23 years the oldest known with BABS. His seizures emerged at age 14 years, and multiple seizure types have been observed including atypical absence, atonic, and generalized tonic-clonic. Treatment has been challenging as no controlling medication has been identified.
Brain MRI Findings
Abnormalities identified on brain MRI vary quite broadly without a unifying pattern, although cystic lesions have been reported, and nonspecific white matter changes (loss, hyperintensity, signal abnormality) have been observed in six of nine affected individuals.
Other
Because this is a newly recognized condition, it is unclear if the following findings are associated with BABS or represent rare co-occurrences, as the findings have been found in a small number of affected individuals.
• Hearing loss. One individual had unilateral congenital sensorineural hearing loss. Three individuals have required myringotomy.
• Congenital heart disease. Mild pulmonary stenosis has been reported in one affected individual and ventricular septal defect (spontaneously-resolved) was reported in another.
• Nail anomalies. Two affected individuals had brittle nails and another had hypoplastic toenails.
• Ophthalmologic findings. One reported individual had esotropia, pseudostrabismus, and bilateral myopic astigmatism.